Microbial degradation of Polyethylene Terephthalate (PET)

Scoping Review on

Table of Contents
Introduction.................................................................................................................................................................3
Background on Plastic Pollution and Its Environmental Impact..............................................................................3
Microbial degradation as a solution: An overview...................................................................................................4
Objectives of the Scoping Review...........................................................................................................................4
Methodological Approach and PRISMA.......................................................................................................................5
Search Strategy........................................................................................................................................................5
Criteria for Selecting the Literature........................................................................................................................10
PRISMA Diagram Steps...........................................................................................................................................16
Annotated Summary: Microbial Degradation of Plastics.......................................................................................17
Strengths and Weaknesses of the particular Review..............................................................................................18
Scope of the Review...........................................................................................................................................18
Limitations of the Review......................................................................................................................................19
Results....................................................................................................................................................................... 22
Overview of Microbial Degradation Mechanisms..................................................................................................22
Enzymes and Microbial Strains Involved...............................................................................................................23
Factors Influencing Degradation Efficiency...........................................................................................................24
Challenges in Biodegradation Processes................................................................................................................25
Emerging Strategies and Technologies..................................................................................................................28
Discussion..................................................................................................................................................................29
Synthesis of Key Findings.....................................................................................................................................29
Gaps in Current Research.......................................................................................................................................30
Future Directions and Potential Applications.........................................................................................................32
Conclusion.................................................................................................................................................................35
Summary of Findings.............................................................................................................................................35
Implications for Policy, Research, and Industry.....................................................................................................36
Policy Implications................................................................................................................................................ 36
Research Implications............................................................................................................................................36
Industry Implications.............................................................................................................................................37
References.................................................................................................................................................................39
Appendices................................................................................................................................................................ 45
PRISMA Diagram....................................................................................................................................................45

Annotated Summary: Microbial Degradation of Plastics.......................................................................................46

Introduction

Background on Plastic Pollution and Its Environmental Impact

Plastic pollution remains one of the increasing global concerns that have serious consequences on

sustainability of the environment. Plastic pollution has become rampant in the world and more so single-

use plastics that have led to a massive increase in plastic waste in different ecosystems with negative

impacts on the environment. Polyethylene terephthalate (PET) which is one of the most used polymers in

the world in packaging items, textiles and other final consumer goods is one of the polymers most

hazardous to the environment due to its stability. This has a long-term implication given that it hardly

undergoes natural degradation hence persisting in the environment impacting on biota and human health in

landfill, marine and terrestrial ecosystems globally (Afshar et al., 2023; Joseph et al., 2024).

Still, it becomes a huge problem for Lithuania and many other countries in Europe to cope with

management of plastics, including PET. According to data, in 2022, the overall scale of plastic waste in

Lithuania was around 230 thousand tons, and PET products took a rather high percentage of this amount

(Rangel-Buitrago & Neal, 2023). Despite the existing recycling precautions such as the national deposit

return of plastic bottles, the recycling of this type of plastic is done inefficiently, and it is estimated that

only 45% of this plastic waste is recycled while the rest is dumped into the landfills or even burnt (He et

al., 2023). This also reflects trends in waste management systems in Europe where there is improvement in

technology in recycling but most plastics wastes are not effectively managed polluting the environment

and contributing to emissions of greenhouse gases (Maurya et al., 2020).

In contrast, the nations with the best waste disposal structures including Germany and Sweden

have recycled more than 60% thus practicing the waste management techniques that avoid landfilling and

burning of waste (Rhodes, 2018). However, Lithuania’s course, even if laudable, entails some drawbacks

and has less potential to be developed into a larger-scale program to tackle the problem of plastic waste,

especially for polymers like PET that confuse biodegradation (Iroegbu et al., 2021).

Microbial degradation as a solution: An overview

Biodegradation has recently been considered as one of the most effective ways of dealing with the

issue of plastics. This process entails utilization of microorganisms including bacteria, fungi and algae to

degrade plastic polymers into simpler non toxic products which the microorganisms can metabolise. As

for PET, specific microbial strains synthesise enzymes including PETase and MHETase that are able to

complete ester bonds in PET and therefore degrade it into substances that are less hazardous to the

environment (Khairul Anuar et al., 2022).

Studies done in Lithuania and other countries have also demonstrated that microbial degradation of

PET could harbor great potential in the disposal of wastes. Nonetheless, due to the properties of the

microbial strains and the conditions under which the degradation takes place, the efficiency of microbial

degradation depends with the environmental conditions, as well as on the physical and chemical

characteristics of the PET material (Cai et al. 2023). For instance, researchers have proven that Ideonella

sakaiensis bacteria are capable of breaking down PET, although the process is slow and needs

improvement in a number of ways.

Microbial breakdown of wastes can also be used in waste management systems as a less expensive

strategy for sustainable waste disposal than burning and dumping that cause pollution and natural resource

exhaustion (Yasin et al., 2022). Through the help of technological advancement, scientists were able to

unlock the degradation of PET by microorganisms hence enabling mankind minimize theنیو

consequences of plastic waste and embrace circular economy (Joseph et al., 2024).

Objectives of the Scoping Review

The main purpose of this scoping review is to offer an extensive synthesis of the existing

knowledge on the microbial degradation of PET and identify research gaps with regard to its potential

implementation in Lithuania. The review will determine the mechanisms by which microbes degrade PET,

the enzymes and the microbial strains that have been investigated as well as aspects that affect efficiency

of the degradation of PET. This includes a comparative analysis of Lithuania´s waste management

practices compared to other European countries for evaluating possibilities of implementing microbial

degradation into the existing management plans.

The review is also going to discuss the disadvantages of microbial degradation including the

factors that inhibit the large-scale application of microbial process and the economic viability of Microbial

Technologies (Mohanan et al., 2020). Furthermore, new development of engineering microbial enzymes

for the PET degradation efficiency will be discussed, further strategies and technologies for boosting

microbial degradation processes (Barclay & Acharya, 2023).

Hence this paper aims at providing a review of the existing literature with a view of demarcating

the existing research gaps and suggesting potential topics for future research with a view of enhancing the

path ways of biodegradation of PET. These further findings shall be expounded in terms of policies,

research and industries to establish strategies that may reduce the effects of plastic pollution in Lithuania

and other nations (Salinas et al., 2023).

Methodological Approach and PRISMA

Search Strategy

The research is based on a literature search conducted in the following databases: Scopus, Web of

Science, Google Scholar, PsycInfo, and ScienceDirect by a single assessor. The latest literature search was

on August 30th, 2024. Reports, published studies, reviews, and reports were searched by applying a

systematic search following a comprehensive search strategy (Table 1).

Table 1. Search strategy

Database Search Search Terms Results

Scopus – 20.06.2024 #1 "Polyethylene 78

Terephthalate" [MeSH

Terms] OR "PET

degradation"

[Title/Abstract] OR

"Plastic biodegradation"

[MeSH Terms] OR

"enzymatic degradation"

[Title/Abstract] OR

"polyesterase"

[Title/Abstract]

#2 "Microbial degradation"

[MeSH Terms] OR

"microbial consortia"

[Title/Abstract] OR

"plastic waste

biodegradation" [MeSH

Terms] OR "microbial

enzymes" [Title/Abstract]

#3 "biodegradation

pathways" [MeSH Terms]

OR "enzymes"

[Title/Abstract] OR "PET

hydrolases"

[Title/Abstract] OR

"biodegradation

mechanisms"

[Title/Abstract] OR

"PETases" [Title/Abstract]

#4 #1 AND #2 AND #3

Web of Science search –

20.07.2024

#1 TS=("Polyethylene

Terephthalate" OR "PET

degradation" OR "Plastic

biodegradation" OR "PET

hydrolysis")

#2 TS=("Microbial

degradation" OR

"microbial consortia" OR

"plastic waste

biodegradation" OR

"microbial enzymes" OR

"polyesterase activity")

#3 TS=("enzymatic

degradation" OR "PET

hydrolases" OR

"biodegradation

mechanisms" OR

"biocatalysis")

#4 #1 AND #2 AND #3

Google Scholar search –

12.07.2024

#1 "Polyethylene

Terephthalate" OR "PET

degradation" OR "Plastic

biodegradation" OR

"synthetic polymers"

#2 "Microbial degradation"

OR "microbial consortia"

OR "plastic waste

biodegradation" OR

"enzymatic breakdown"

#3 "enzymatic

degradation" OR "PET

hydrolases" OR

"biodegradation

mechanisms" OR

"biocatalysts"

#4 #1 AND #2 AND #3

ScienceDirect search –

13.07.2024

#1 "Polyethylene

Terephthalate" OR "PET

degradation" OR

"Biodegradable plastics"

#2 "Microbial degradation"

OR "PET hydrolases" OR

"Plastic biodegradation

mechanisms"

#3 "Enzymatic

degradation" OR

"microbial enzymes" OR

"biodegradation pathways"

#4 #1 AND #2 AND #3

SpringerLink – 11.08.2024 #1 "biodegradation" OR

"microbial degradation"

OR "plastic waste"

#2 "enzymatic pathways"

OR "biodegradation

enzymes" OR "microbial

breakdown"

#3 #1 AND #2

The present scoping review shall be done following the Preferred Reporting Items for Systematic

Reviews and Meta-Analyses (PRISMA) checklist to maintain validity and reliability in the process of

identifying and including relevant research materials relevant to the study question. The review of the

literature sources will be based on publications which are made within the last ten years: scientific articles,

conference materials, and other sources which present the information about the microbial degradation of

the PET, focusing on Lithuanian conditions. Specificity in the selection and rejection of papers will be

established, and the parameters of the systematic review’s purpose and coverage shall be described

(Afshar et al., 2023).

Criteria for Selecting the Literature

Literature selection for this scoping review was done according to a defined procedure meant to

make sure that the scoping review covered as many aspects as possible while being as specific as possible

in the process. Since microbial degradation of Polyethylene Terephthalate (PET) is a relatively

complicated process, it was critical to set out guidelines on how the inclusion of studies could be done

while excluding substandard studies. PRISMA guidelines were used while formulating the criteria and

these documentations help in keeping a check on the transparency, consistency, and replicability of

systematic reviews as well as scoping reviews (Moher et al., 2009).

1. Study Type and Design

The categories of research papers included in this particular review were chosen depending on their

design and existing input to the area of microbial degradation of PET. This was done with research articles

which included quantitative and qualitative data as well as review papers and conference papers that

presented theories and comprehensive reviews of a particular topic. In general, papers which involved

basic investigation as well as detailed identification and description of microbial cultures or enzymes

responsible for PET degradation in experimental approaches were considered. Thus, in most of such

studies a great emphasis is placed on the biochemical pathways and conditions favorable for microbial

degradation.

For example, studies that used high throughput screening methods to discover new PET degrading

microorganisms that would be useful to the process received a lot of attention. Such research work that

uses sophisticated techniques such as genomic microarrays for analyzing variations in enzyme activity in

these microorganisms to advance genomic sequences and proteomics were also favored as these provided

key insights on biotechnological possibilities the database portrays. Furthermore, literature that examined

the effects of microbial degradation on the environment including shift in microbial community due to

PET pollution were also incorporated to give an overview of the biodegradation process.

This means that whereas work centered on chemical or thermal degradation processes not likely to

promote microbial action, such analysis is useful in establishing the general behaviour of PET in the

environment. Thus, the present review does not consider studies on PET degradation by chemical

processes. Likewise, articles that presented theoretical analysis without the empirical support, opinionated

articles, articles that were purely theoretical without experimentation or articles that were considered as

reviews but contained no critical analysis were excluded to keep the study’s analysis and conclusions

scientific.

2. Date Range

The date filter used in this review while selecting the articles which were published between 2010

and 2024 has been deliberately selected so as to obtain a blend of the most basic research in this field and

the latest contributions made by the scholars. The last decade began to understand the strategies of

microbial degradation of the PET at a faster pace due to advancement in molecular tool that led to

discovery of new enzymes and PET degrading microbial species. Hence, to cover these advancements the

studies retrieved are from and after 2010 only are included in the review.

The pre-2010 studies were included only when these represented promising works, which set the

direction for the further studies. For instance, some papers that reported PETase, an enzyme that is key to

the degradation of PETs were accepted for the category even when they were published before the year

2010.

This way the effect of including papers up to year 2024 provides the scope of the present state of

understanding regarding microbial degradation of PET up-to-date, recent identification of more effective

microbial strains and enzymes, along with enhancement in biotechnological fields. This temporal scope

also enables the review to capture the emerging discourses on the feasibility of microbial degradation

processes as well as their contribution towards the future configuration of industrial waste disposal

systems.

3. Geographical Focus

Although this year’s review has intended to be as inclusive as possible, it has focused on the

literature most pertinent to Lithuania and the Baltic states. Lithuania follows region and EU environmental

policies and management of waste as a result, the comparison should be made with countries operating

within the similar setting. This geographical focus was chosen to make sure that the findings of the review

will apply to Lithuania’s geographical context and problems of waste management as well.

For instance, the investigation of biodegradation of PET under temperate climate conditions like

in Lithuania was priorised. Studies carried out in other EU member states were also incorporated since

they have similar waste management objectives in the Stockholm’s circular economy plan that is

spearheaded by the EU. This approach enabled the comparative consideration of how the microbial

degradation technologies can be applied and what considerations need to be taken into account when

implementing technology in Lithuania in terms of environmental conditions and the existing infrastructure

of the waste management system.

At the same time, investigations carried out in climatically different or having different waste

treatment systems were considered if they shed additional light on mechanisms of microbial degradation

or biotechnological developments potentially transferable to Lithuania. For example, studies originating

from tropical climates may provide information as to what types of microbial species would function in

warmer climates and what may be predicted as to how microbial degradation processes might be

influenced as a result of climate change in Lithuania.

4. Language

Language is one of the ways through which the authors can make sure that the review covers as

much information as possible while at the same time being easy for the reader to understand. Although the

languages of scientific production are mainly English and the studies reviewed here too are predominantly

in English, this review aimed at the research in Lithuanian and other Baltic languages as well. This was

done to avoid limitations which effect regionally produced work, some of which may not be easily

accessible in English.

In practice, it meant that attempts were made to obtain and translate Lithuanian language

publications, especially the ones concerning Lithuanian waste management practices or microbial culture.

The incorporation of non-English studies was completed with a certain measure of trepidation, however,

because the quality of translated manuscripts and the amount and quality of the methodological

information provided to the coordinators could be inconsistent. However, it was quite important to cover

broad sources of different languages in order to overview the current state of research concerning

Lithuania.

5. Research Quality

To minimize the possibility of including studies which do not meet specific quality standards, a

number of inclusion criteria were used; hence, only quality research studies were incorporated into this

review. The process also entailed assessing the quality of the method used in each of the studies such as

the comprehensiveness and relevance of the research design, the sample size used in the study and the

means used in data collection process as well as the validity of the analytical techniques employed.

For example, empirical research that included the use of rigorous research methods like the

randomized controlled trials or good laboratory experiments was preferred. Because of the high level of

detail and accuracy associated with the following methods, particular attention was paid to studies that

involved sophisticated analytical methods including genomic sequencing, proteomics, or metagenomics in

recognition of microbial strains able to degrade PET.

On the other hand, studies with minor or major methodological issues like small number of

participant samples that may not be representative of the general population, inadequate or biased ways of

data collection and analysis or insufficient data to support the authors conclusion were either sidelined or

completely omitted from the review process. This selective process was considered important in checking

for the quality of evidence that informed the review hence improving the reliability and validity of the

conclusions made.

6. Thematic Relevance

This was a factor for consideration in the choice of the literature since each analysis had to have a

theme. The present review was confined to evaluating articles that dealt with issues relevant to microbial

PET degradation in terms of identification of microbial strains/ enzymes, factors influencing degradation

efficiency and biotechnological factors, factors pertaining to scaling up of the microbial degradation

processes, and studies on the potential utilization of such degradation technologies for waste management.

Since efforts to investigate all important aspects of the microbial degradation of PET, the review

included works from several fields such as microbiology, environmental science, biotechnology, and

waste management. Such an approach was necessary to describe the process of biodegradation, which is a

function not only of catalysts but also of environment.

Some papers not previously classified into these themes were not included, for instance, papers

that discussed about the effects of plastics on environment without mentioning microbial degradation. Due

to this focus on the thematic relevance it was possible to stick to the objectives of the review and create a

holistic and logically coherent overview of the state of the art regarding microbial degradation of PET.

7. Availability of Full Text

The factors for inclusion into the review included full-text availability and other features to be

mentioned later in the paper. The investigations for which full text access was available only were

considered, thus, excluded from the analysis those works, the methodology and results of which were

insufficiently represented. This criterion was considered crucial for the purpose of enhancing the

objectives of the review because it helped the filter out certain aspects of each study and provided an

insightful perception on its significance.

If a specific study related to the question was found relevant to the let but the full text was not

readily available, the authors tried to gain full-text access through his/her institutional affiliation, through

inter-library loans and by requesting the authors of the articles. This approach made it possible to get

papers regardless of the authors’ ability to pay for journal access, thereby making the review more

inclusive.

8. Inclusion of Grey Literature

It was deemed necessary to consider grey literature to complement the published literature include

government reports, policies and industry white papers. Grey literature constitutes important information

on innovative technologies on policies, and business practices which may have not yet featured in

scholarly journals. For instance, if a government of Lithuania released reports on practices of waste

management and they offered new perspectives on the respective field, the sources were used.

However, the involvement of gray literature was done sensitively in view of the fact that most

materials are self-published and there is no peer review. For each item identified under the grey literature

category, the source of the study, credibility of data used and relationship with the objective of the review

was assessed. Such documents were selectively used in the review as only those documents reflected the

concepts and met the above criteria.

PRISMA Diagram Steps

1. Identification

oTotal records identified through database searching: 41

oAdditional records identified through other sources: 0

oTotal records after duplicates removed: 41

2. Screening

oRecords screened: 41

oRecords excluded: 10 (Due to irrelevance or lack of focus on microbial degradation of

plastics)

3. Eligibility

oFull-text articles assessed for eligibility: 31

oFull-text articles excluded: 6 (Reason: Lack of specific data on degradation processes or

methodologies)

4. Included

oStudies included in qualitative synthesis: 25

oStudies included in quantitative synthesis (meta-analysis): N/A

Annotated Summary: Microbial Degradation of Plastics

Source Aim of the Study +

Description

Used Measures and

Tools

Outcome of the

Study

Afshar et al. (2023) Review of

biodegradable

plastic degradation

in waste

management and

Literature review,

analysis of

degradation

processes

Highlights gaps in

current

biodegradation

methods, suggests

areas for

the open

environment

improvement in

waste management

systems

Ali et al. (2021) Examination of

plastic waste

biodegradation

mechanisms and

future prospects

Analytical methods,

laboratory testing

Identifies key

microbial pathways

and enzymes, notes

challenges in large-

scale application

Bahl et al. (2021) State of the art

review on

biodegradation of

plastics

Review of current

technologies and

microbial

approaches

Summarizes

effectiveness of

various microbial

strategies for plastic

degradation

Barclay & Acharya

(2023)

Engineering plastic-

eating enzymes

using structural

biology

Structural analysis

of enzymes, genetic

engineering

Developed enzymes

with enhanced

degradation

capabilities,

potential for

industrial

application

Barrick et al.

(2021)

Challenges in

ecotoxicological

hazard assessment

of plastic additives

Review of

ecotoxicological

testing methods

Discusses

limitations of

current hazard

assessment tools

and the need for

comprehensive

testing

Benavides

Fernández et al.

(2022)

Systematic review

on microbial

degradation of

polyethylene

terephthalate (PET)

Review of existing

studies, meta-

analysis

Identifies effective

microbial strains,

highlights

challenges in

accelerating PET

degradation

Cai et al. (2023) Recent perspective

on biological

degradation of

Laboratory

experiments,

environmental

Evaluates

influencing factors

in microbial

plastics and

microplastics

analysis degradation,

suggests strategies

to enhance

efficiency

Carmen (2021) Review of

microbial capability

for degrading

chemical additives

in plastics

Review of

microbial pathways

and enzymes

Highlights potential

microbial solutions

for reducing plastic

toxicity

Ghosh & Jones

(2021)

Roadmap for

developing

biodegradable

plastics

Analysis of current

biodegradable

plastic technologies

Proposes a roadmap

for future research,

identifies key areas

for innovation

He et al. (2023) Advances and

challenges in

enhancing plastic

biodegradation

Laboratory

experiments, field

studies

Discusses strategies

to improve

microbial plastic

degradation,

addresses current

limitations

Strengths and Weaknesses of the particular Review

Scope of the Review

These criteria were used to define the scope of this scoping review closely in relation to the

associated research questions concerning the microbial degradation of PET with specific emphasis on the

viability of these technologies in Lithuania. This included analysis of the existing literature about

microbial PET degradation, which encompassed identification of microbial strains and enzymes unique to

PET degradation, the environmental and biotechnological aspects of PET breakdown, and prospects and

limitations to up-scaling microbial degradation processes.

The review also aimed at attempting the applicability of microbial degradation technologies within

the parameters of the existing waste management practices in Lithuania, taking into account the principles

of environmental legislation of the country and available waste management structures. This emphasis on

Lithuanian situation was made to guarantee that the propositions, derived from the review, would be

relevant to the existing problem and trend in Lithuania, for policymakers, industry players and researchers.

An effort was made to cover as many publications as possible belonging to different fields of

sciences such as microbiology, environmental sciences, biotechnology and waste management sciences.

This made it possible to have an interdisciplinary approach in the understanding of biodegradation process

and its prospects. The review also included work from different geographical areas as well as putting an

emphasis on Europe and other temperate zones that are similar to Lithuania’s environment.

Limitations of the Review

However, there are the following limitations that have to be mentioned even conditioned by the

present work’s stringent approach to the analysis of the sources. First, it has not included studies published

in languages other than English, Lithuanian and other Baltic languages. As attempts were made to select

papers focusing on non-English studies in a bid to make the findings more relevant to regional studies, the

language bias might have caused the elimination of other studies in other languages especially from non-

European countries. This limitation could also limit a generalisability of some of the findings towards the

research trends and interests of the English speaking and European countries.

Second, there was limitation to the number of studies that offered full text access to them papers

under consideration. Although a lot of efforts were put in an endeavor to secure full text papers for the

review, there were limitations in accessing some of the papers. This limitation could have led to a neglect

of some potentials of research especially from institutions with small research funding, limited access to

international publication as well as those that are not privileged to access some academic journals.

Third, the use of the peer-reviewed literature, although providing a certain level of methodological

stringency to the analysis, might have led to the elimination of the research that are innovative or pilot in

nature and have not passed the peer- review process yet. To address this limitation, it was planned to

incorporate grey literature, but while doing so special attentiveness was paid to the presence of biased

information and the lack of peer review in the given type of sources. As a result, it may be the case that

some most recent academic studies or some practices in the field were left uncovered in the review.

Fourth, specificity of the Lithuanian context is beneficial from the perspective of local actors, yet

such specificity may hinder the review’s applicability to the other contexts much different in terms of

environment, waste management, and legislation. As with many of the other systematic reviews, this

incorporated research from multiple geographical areas, however it is the focus on Lithuania and therefore

the results may be most salient to those nations with comparable climates and/or nations that align

themselves with EU policies.

Finally the time limit of the review was set to consider the studies published from the year 2010 to

2024, to capture the most recent trends in the field. Although, this may have brought some bias in the

sense that the research dashed out the recent years and in doing so, left out some yet beneficial information

from foundational studies. Conversely, as some important previous studies, which were published prior to

2010, were left out of the review, the authors might have missed some potentially important, previous

research that still presently shapes future studies.

Bias: Blindness and Referee Check to PRISMA Guidelines & Publication of Review

PRISMA guidelines were followed in the research methodology since they are useful in making

the selection and analysis of the literature methodical and systematic. The application of PRISMA

guidelines assisted in following a certain laid down procedure in reporting thus enabling other researchers

to try and use the results of this review as a base for their own.

PRISMA also helped in the recognition of biases and limitations in the studies selected for

inclusion, thus minimizing bias when appraising the findings of the given studies. In carrying out the

review to follow PRISMA guidelines, the goal was to ensure that the process of the review was thoroughly

explained so as to increase the reliability and credibility of the study.

This was because PRISMA’s systematic approach to the identification of literature and data

extraction was helpful in handling many papers that had to be reviewed for the final consideration. Thus,

the application of the PRISMA flow diagrams enabled a clear display of the study selection, making the

decisions regarding addition or exclusion more clear. This transparency is important in guarantee that the

review addresses al the literature or sources without bias.

Furthermore, with regard to transparency, the PRISMA checklist highlighted areas which were

relevant for the reporting of the review’s limitations. By stating the limitation of the present review such as

the possible bias in the selection of the analyzed articles and due to language barrier and accessibility of

the articles, the present review aimed to give a critical and comprehensive appraisal of the current

literature regarding microbial acting on PET.

The approach used in the present scoping review was aimed at identifying a broad spectrum of

evidence regarding the microbial degradation of PET applied within the Lithuanian context. As a result of

reading through the literature in strict compliance with the selection criteria, stating the novelty and

limitation of the present work, and following the PRISMA guidelines, this study provides useful

information about the existing literature and the possibilities of microbial degradation technologies in the

context of waste management. However, the review provides the researchers and policy makers with a

strong base for the future explorations in this significant field of study.

Results

Overview of Microbial Degradation Mechanisms

Biodegradation of PET has recently gained attention as a sustainable solution for dealing with

plastic pollution issue as an effective and ecofriendly approach to conventional techniques of plastic

disposal including burning and dumping. The mechanism of biodegradation is defined as breaking down

of the PET polymers by microorganisms that assimilate these polymers into less complex, non-harmful

substances (Benavides Fernández et al., 2022). This degradation is achieved through a number of chemical

transformations including hydrolysis where certain enzymes that include PETase and MHETase are

involved in breaking the ester bonds in PET hence its depolymerization into monomers like TPA and EG

respectively (Khairul Anuar et al., 2022).

There are several factors which affect the efficiency of microbial degradation of PET these are

type of microbial strains involved, environmental conditions under which degradation is likely to occur,

physical and chemical characteristics of PET material (Cai et al. 2023). Fluorinated compounds like PET

have received special attention as biodegradation strategy and depending on the specific type of

microorganism, different approaches for the degradation of PETs are available and differ largely in their

effectiveness. For instance, Ideonela sakaiensis bacteria are capable of producing enzymes that are capable

of decomposition of PET while other bacteria may use non-specialized enzymes for the same purpose

(Kotsha 2022, p. 46).

Besides bacterial degradation, there are fungi and algae which are believed to have the ability and

capability to degrade PET. Fungal species have attracted more attention owing to their potential to secrete

a number extracellular enzymes that can potentially depolymerise numerous polymers including PET,

(Joseph et al., 2024). Plants, however algae are relatively investigated, they have some benefits because

they can be cultivated in aqueous environment the greater part of which recollects the plastic waste (Yasin

et al., 2022). Knowledge of these microbial processes is vital in the formulation of realistic approach to put

into practice microbial capacities for the degradation of plastics at an industrial level.

Enzymes and Microbial Strains Involved

This involves the isolation and description of certain enzymes and microbial strains that problems

are able to decompose PET are the key to the microbial degradation of PET. Among them, Ideonela

sakaiensis produced enzyme called PETase which been one of the most important findings. PETase

synthesises its own PET by transforming TPA and EG into PET hence making the enzyme the main focus

of research to boost the efficiency of PET biodegradation by microbes (Khairul Anuar et al., 2022).

Apart from PETase, MHETase is another enzyme that is said to have a great function in the

degradation process. Finally, MHETase needs to degrade the intermediate product mono (2-hydroxyethyl)

terephthalic acid (MHET) to TPA and EG as shown by PETase (Cai et al., 2023). The combined action of

PETase and MHETase has been observed to increase the rate of PET degradation, and thus represent

targets that are vital for biotechnological improvement.

Apart from Ideonella sakaiensis, there are other microbial strains that have been reported to

possess ability to break down PET. For instance, Thermobifida and Fusarium species have been identified

to synthesize enzymes comparable to PETase though in a different levels of efficacy (Benavides

Fernández et al., 2022). These strains present other targets for investigation, especially, on the dependence

of enzyme’s activity and stability on the environment.

Aspergillus and Penicillium species of fungi are also reported to possess capability of bio-

degradation of PET. These fungi release different kinds of enzymes the extracellular environment,

enzymes such as cutinases, and lipases that have been proved to degrade PET at certain conditions (Joseph

et al., 2024). Due to the lower number of enzymes produced by fungi as compared to bacteria, it can be

assumed that fungi may provide more universal solutions for PET degradation in various environments.

Further, algae have been established to have the ability to prospect for PET degradation especially

in marine ecosystems. Known PRD algae species were shown to secrete enzymes that can degrade PET;

however, the studies in this field are rather limited (Yasin et al., 2022). The inclination of algae to grow on

plastics and substances floating on the water makes algae an ideal subject of future researches.

Factors Influencing Degradation Efficiency

Microbial degradation of PET depends on several factors and factors such as the environmental

conditions, characteristics of the chemical and physical property of PET and the microbial strains (Cai et

al., 2023). Temperature, pH and the presence or absence of oxygen in the environment to exert large

influence on the PET-degrading enzymes and the degradation process in general.

One of these factors is temperature as activity of enzymes usually rises with the increase in the

temperature to a certain physical entity which is referred to as optimum temperature above which the

enzyme may decompose and is rendered useless (Barclay & Acharya, 2023). For instance, The PETase

from Ideonella sakaiensis has been observed to have an optimal activity at 30°C, where the activity

decreases with increase in temperature to 60°C and above, thus making it less suitable for use in industries

that require high temperatures (Khairul Anuar et al., 2022).

The other factor that an enzyme has to do with is the pH of the surrounding. Highly, most PET-

degrading enzymes have this preference in a certain pH that if changed, the rate of degradation will be

lower accordingly (Benavides Fernández et al., 2022). For instance, PETase enzyme exhibits the highest

level of activity in slightly alkaline environment, approximately at 7. 5-8. 5; this is in light with

environments found in many natural systems but may not well suit the industrial setups.

Several characteristics of the original PETmaterial – which includes crystallinity of the material,

the molecular weight of polymer, and the surface area – also impact the degradation pathway (Huang et

al., 2018; Iroegbu et al., 2021). Crystalline PET is less vulnerable to microbial attack as compared to

amorphous PET as the molecular structure of the former is closely compact that reduces accessibility of

enzymes (Maurya et al., 2020). On the other hand amorphous PET, which is less ordered, is more reactive

and thus prone to enzymatic degradation. Chemical treatments or mechanical abrasion of the PET surface

also help in increasing the PET biodegradation rate as it increases the surface area of PET and decreases

crystallinity which in turn allows microbial enzymes to attack (Joseph et al., 2024).

Another factor is Oxygen is also limited since aerobic microorganisms require oxygen for their

metabolic activities (Rhodes, 2018). Anaerobic conditions, which are relatively simple to provide

especially in most landfills and many aquatic environments, are those that slow down the degradation

process or even inhibit the process all together. Nonetheless, there are some microorganisms that have

been proved to decompose polyester under anaerobic environments but at a slower rate and therefore call

for more investigations on anaerobic biodegradation mechanisms (Yasin et al., 2022).

Challenges in Biodegradation Processes

However, the following are the challenges faced in the process of microbial degradation of plastics

making it hard to have widespread use: An important disadvantage that is discussed is the fact that when it

comes to breakdown, the rate is considerably slow. Despite the fact that enzymes like PETase has the

capacity to degrade PET, the process is very slow and may take weeks or even months to achieve a

considerable level of degradation thus making it very impractical in waste management solutions (Kotsha,

2022). This slow rate of degradation is especially disadvantageous when faced with the huge volumes of

PET waste which requires faster and more efficient degradation procedures.

The last one of these challenges is the issue of the ability to scale up microbial degradation

processes. Although lab experiments have shown the feasibility of microbial degradation, translating such

processes to an industrial level is a major challenge from a technical and economic point of view

(Mohanan et al., 2020). The lack of adequate and cheap production of microbial enzymes is among the

biggest challenges next to the lack of knowledge on how best to harness these enzymes. Moreover,

reliance on specific temperature and pH rates makes it difficult to scale up these methods to another level.

The same applies to the stability and activity of PET-degrading enzymes under various conditions

as well as other factors, such as biodegradation rates and enzyme specificity. Most of the aforementioned

enzymes are affected by temperature, pH and the presence of inhibitors that render its applicability in the

real world reduced (Cai et al., 2023). For instance enzymes that have very high catalytic activities in

artificial environments such as laboratory may denature, or lose their activity in real world environments.

The breaking down of organic compounds by microbes can be an economic issue however, another

important aspect to consider. As much as the utilisation of microorganisms to break down PET is

environmentally appealing, the costs pertaining to the production of these microorganisms and the

enzymes together with their application at a commercial level are very expensive. As observed on the

current situation, technology and cost are the major factors that can spur microbial degradation to meet the

goal of managing PET waste.

In addition, there are issues concerning application of genetically modified microorganisms

(GMOs) which are intended for enhanced degradation of PET. There are some questions in the use of

GMOs in waste management and disposal: there are ethical questions such as regulation of GMOs and

effects of releasing such organisms into the environment (Joseph et al., 2024). This however poses a big

concern in that the safety and environmental compatibility of these microorganisms must be established

before they can be mainstreamed.

Engineering of plastics for their degradation through the enhanced properties of enzymes.

Because of the inherent drawbacks in natural PET-degrading enzymes, enormous investigations

have been focused on the improvement of the enzymes. Scientific progress especially in the field of

molecular biology and protein engineering has enabled the optimisation and improvement of activity,

stability and specificity of enzymes that degrades PET and therefore making them suitable for the

industrial uses(Barclay & Acharya, 2023).

The technique of directed evolution has been found to be most applicable in this area because it

uses principles of natural selection in the course of generating enzymes of better characteristics. Random

mutations have been introduced into gene encoding PETase followed by selection for variants with

increased activity with the result that researchers have got the PETase variants that hydrolyze the PET

more effectively and at faster rates than the wild type PETase (Khairul Anuar et al., 2022). These

engineered enzymes have also demonstrated enhanced degradation rates and thermal stability thus making

them suitable for extensive use in different industrial processes.

The other discipline utilizes the actual design of enzymes with an aim of realizing their geometrical

figure. Based on studies on the structure of PETase, researchers have easily isolated amino acid positions

that participate in substrate interaction and catalysis (Khan et al., 2023). Alterations of these residues have

enabled enhancement of substrate specificity and catalytic rate constant of PETase variants. Also based on

structural information enzyme variants that peracute in extreme conditions; high temperature, high or low

pH, enzyme has been developed widening their usage.

Besides engineering the single enzymes, scientists also discussed the construction of the

multienzyme systems which can act cooperatively in the PET degradation process. For instance, the

cascade immobilization of PETase and MHETase – either in separate microorganisms or integrated in the

same biocatalyst by fusion protein – improves the overall degradation process by rapidly converting the

intermediate products to monomers (Joseph et al., 2024). This approach is beneficial for the enhancement

of the PET degradation efficiency and also minimizes the concentration of the intermediate compounds

that may lead to hazardous effects after their formation.

Recent development in synthetic biology ideas has further extended the development of methods to

design microbial systems for degrading PET. With metabolic engineering, it is possible to develop

bioheterogeneous PET degrading microbial systems, or in other words microbial consortia or synthetic

ecosystems that can more efficiently degrade PET since the microorganisms within the designed

communities express several enzymes responsible for PET breakdown (Barclay & Acharya, 2023).

Furthermore, these engineered microbial systems can be designed to accommodate a given environment

and thus can be used in different waste management situation.

Emerging Strategies and Technologies

In addition to enzyme engineering, several other innovation strategies and technologies show

potential for improving the microbial decomposition of PET. One of them include the establishment of

various predictive and computational models using bioinformatics and machine learning to foresee and

design new enzymes capable of breaking down PET. From the analysis of big data of enzyme sequences

and structures, the machine learning can give potential PETases and other related enzyme sources of a

large number of organisms, thus promoting the rapid discovery of new enzymes (Cai et al., 2023). These

computational tools also allow the predicting of the interactions between enzymes and substrates and thus

the development of efficient enzymes for degrading the target materials.

The other future advancement is that of bioreactor systems that are constructed purposely for the

degradation of PET. Theses bioreactors can also offer controlled condition that enhances microbial

degradation consist of temperature, pHe, and DO levels (Benavides Fernández et al ., 2022). These

bioreactors can have enhanced degradation rates and higher efficiency compared to the conventional waste

treatment technologies as a result of complex of engineered microorganisms or enzyme complexes. In

addition, the process takes advantage of bioreactors for the capture and reuse of the degradation products,

including TPA and EG, for recycling.

Photobiocatalysis is another innovative process which is based on the integration of

photochemistry and biocatalysis to further degrade the PET. Through the light activated enzymes or

photosensitizers, it is possible to enhance the PET degrading enzymes’ activity to depolymerize PET

under ambient conditions (Yasin et al., 2022). Of these, this technology is especially appropriate for use in

the exterior settings, especially where a source of light, such as sunlight, can be used to power the

degradation process.

Nanotechnology also offers potential solutions for improving the efficiency of microbial

degradation. By incorporating nanoparticles into PET materials, it is possible to increase their surface area

and make them more accessible to microbial enzymes (Mohanan et al., 2020). Nanoparticles can also be

used to deliver enzymes directly to the PET surface, enhancing their concentration and activity at the site

of degradation. Additionally, the use of nanomaterials in enzyme immobilization can improve the stability

and reusability of PET-degrading enzymes, making the degradation process more cost-effective.

Finally, the integration of microbial degradation with other waste management technologies, such

as mechanical recycling and chemical depolymerization, offers a comprehensive approach to addressing

PET pollution. By combining these technologies, it is possible to achieve higher overall efficiency in PET

waste treatment and recovery, reducing the environmental impact of plastic waste (Rhodes, 2018). For

example, microbial degradation can be used to break down PET into monomers, which can then be

chemically polymerized into new PET products, creating a closed-loop recycling system.

Discussion

Synthesis of Key Findings

Microbial degradation of Polyethylene Terephthalate (PET) is a great innovation towards

managing plastics pollution in the world. Some of the latest studies presented below support a fact that

thus, microbial degradation by means of an enzymatic process is a feasible and eco-friendly solution to the

concern of PET pollution in the natural environment. The fact that some particular microorganisms are

capable of PET degradation into its monomers like TPA and EG, due to the presence of specific enzymes

PETase and MHETase, has been an important discovery (Khairul Anuar et al., 2022). Apart from

increasing the knowledge on microbial metabolism, this finding also creates new opportunities for the use

of Biotechnology to address the problem of plastic pollution.

Among these factors, conditions of the environment such as temperature, pH, availability of

oxygen, properties of the polymer PET, and other features of the microorganisms affect the overall

degradation efficiency of microbes. For instance, PETase exhibits the best performance at some specific

temperature and pH values and works more effectively when in synergy with other enzymes as the

MHETase (Cai et al., 2023). The degradation process also depends on the crystallinity of PET and the

molecular weight of PET, in which the amorphous state PET is more degradable by enzyme than

crystalline state PET (Iroegbu et al., 2021).

Nevertheless, there are several problems that still persist. The microbial degradation is

comparatively slow, and it is not commercialized up to its maximum potential for the industries. This is

particularly due to the fact that the PET-degrading enzymes need to remain stable under different

environmental conditions; a factor that has not been proven with ease. However, the application of GMOs

for PET degradation may cause environmental issues for which moral and legal questions arose (Joseph et

al., 2024).

To these challenges corresponding advances have been achieved in the field of engineering more

efficient and robust enzymes. The advancement of PETase variants utilizes techniques such as directed

evolution and rational design to improve the activity and stability of the enzyme for use in industrial

processes (Khairul Anuar et al., 2022). In the same regard, progress in synthetic biology have also

provided for the possibility of synthetic microbial communities in which the possible members join forces

in order to degrade PET better. These developments indicate that microbial degradation as valid and viable

component of integrated waste management system in the future.

Gaps in Current Research

Thus although the research done on microbial degradation of PET has shown significant progress,

there are still some areas that require filling for this technology to reach its full potential. The largest

knowledge gap concerns the absence of critical information about the presence and distribution of PET

degrading microorganisms in nature. Ideonella sakaiensis has been the most often studied bacterium to

date, although the expansion of PET-degrading species and their distribution among various biomes

deserves examining (Kotsha, 2022). This gap somewhat hinders the detection and, hence, the exploitation

of new microbial strains that may have enhanced capabilities for degrading the substrate in question.

Another research niche is the absence of systematic investigations of the chronic effects of utilizing

engineered microorganisms for PET degradation. L case experiments using these microorganisms as

biological control agents have proven viable but few people know how these or controlled organisms

operate in avoiding other species in the real environment or potential harm of releasing them (Joseph et al.,

2024). This is especially so where the microorganisms in question are genetically modified, as this may

lead to unimaginable impacts on the biodiverse as well as the functionality of ecosystems.

Another gap of knowledge that research pointed out is the issue of scalability of microbial

degradation processes. Although much attention has been paid to understand degradation mechanisms of

PET at the molecular level, bringing these researches into practice at industrial scale is still a problem

(Barclay & Acharya, 2023). Pet degradation by microbes is still a challenge because the amount of

enzymes produced is not enough, storage and transportation of the enzymes are difficult and the conditions

that lead to optimal enzyme activity have not been determined for use in various waste management

facilities.

Furthermore, this study has involved mostly PET but more work needs to be done to investigate

the fates of other types of plastics which are widely distributed in the environment including

polypropylene and polystyrene (Rhodes, 2018). It is equally important to know if the same microbial

degradation pathways used to degradable the mentioned natural plastics can be extended to such artificial

plastics or if there is the need to design new strategies on how to overcome this form of plastic waste

management.

Last but not the least; there is a need to improve the interlinkage of microbial degradation with

other technologies for waste management. Microbial degradation being an environmental-friendly process

for the degradation of PET holds an extraordinary possibility of integration with mechanical recycling,

chemical depolymerisation or other established technologies (Mohanan et al., 2020). However, studies on

how the employed methods should be integrated are still limited and more research should be invested in

finding the application approaches that would ensure maximum effectiveness and efficiency of the plastic

waste treatment.

Future Directions and Potential Applications

Based on the gaps that have been discussed above, numerous future research prospects can be

noted to assist in the development of microbial degradation of PET and further plastics. Thus, an area that

will need the future research include identification of microbial diversity in various environments with an

emphasis on the new PET-degrading microorganisms. It can be applied for screening of new enzymes as

well as different microbial strains which possess better degradation potential using metagenomic and

bioinformatics techniques (Cai et al., 2023). This could lead to the identification of microorganisms that

are better operative in other environmental injuries which would mean stretching the use of microbial

degradation to areas it was previously uninable.

The second mentioned direction that should be taken is the advancement or enhancement of

enzyme engineering methods to enhance the capability of the PET degrading enzymes. Current trends in

protein engineering including machine learning to predict and engineer enzymes, offer the prospects of

enhancing the activity, stability and selectivity of these enzymes (Khairul Anuar et al., 2022). This may

culminate to the development of enzymes capable of depolymerizing PET under different conditions than

the current prevailing ones and this is because they serve better in industrial applications and even in other

environments that are not so moderate.

That is why, enhancements about impregnated fibers, as well as the creation of bioreactors for

PET degradation exclusively, can be discussed as perspectives of further investigations. These could offer

optimal control over the conditions favorable for microbial degradation including temperature, pH, and

oxygen thereby improving on the efficiency of the process(Benavides Fernández et al., 2022). also

bioreactors could be designed in such a way that they enable capturing and reusing the degradation

products, TPA and EG so that the PET waste will turn into useful materials.

Another developing technology which has implication in the degradation of PET is known as

photobiocatalysis, which is a combination of photochemistry and biocatalysis. Thus, there is potential to

enhance the PET-degrading enzymes or light-activated photosensitizers with a view of further enhancing

PET degradation under normal conditions (Yasin et al., 2022). Perhaps the most relevant application of

this technology could be the degradation of PET in outdoor setting using sunlight as the source of energy

for the process.

The current nanotechnology is also expected to provide solutions for enhanced efficiency of

microbial degradation. Nanoparticles could be used in a manner that improves the PET’s surface area or a

manner that deposits microbial enzymes on to the PET’s surface (Mohanan et al., 2020). Particularly,

nanomaterials could be applied to immobilize enzymes which would enhance their stability and recursing,

as well as would make the process of degradation relatively cheaper. Thereby, the nanocomposure of

microbial degradation could invent new material and system that are suited for better biodegradation.

As for the practical application the use of microbial degradation in the waste management

facilities implies rather great potentialities. Studying the outdoor degradation of microorganisms with PET

waste also has a potential of reducing the volume of PET waste that is channeled to the landfills or

incineration reducing pollution (Barclay & Acharya, 2023). In addition, the results showed that microbial

degradation could be applied in conjunction with other recycling technologies in order to convert existing

waste management systems into more effective and environmentally friendly systems. For instance, PET

that has been bio degraded by microorganisms could be subjected to chemical degradation which helps to

extract monomers that can be recycled back to the PET products manufacturing process.

Another possibility of application of this matter is employing microbial degradation in

environmental management. Microorganisms that can degrade PET can be used in environments that are

affected by the litter which includes seas, rivers, and the ground with an intention of degrading the stuff in

order to reduce its effects on environments (Rhodes, 2018). This seems to be especially true where issues

of accessibility make standard waste disposal a nearly impossible task. However, the positive effects of

using these microorganisms in the treatment of wastewater has to be balanced against the possible

ecological effects of adding such microorganisms into natural ecosystems especially where genetically

modified strains are used.

Facilitating conditions will also include the status of policy and collaborations that will enhance

the use of microbial degradation technologies. In order to achieve this, governments and other industry

stakeholders require a collaborative effort in order to design appropriate regulatory structures and

promotional mechanisms to drive the development as well as adoption of microbial degradation solutions

(Joseph et al., 2024). This could encompass financial support to the development of such technologies,

support to those industries upon implementation of such technologies and even setting of conventions and

codes on the use of these technologies safely and efficiently.

Therefore, even though these studies present considerable advances in the knowledge of microbial

degradation of PET, there is still a long way to go to its application at a commercial level. Asides from

microbial diversity, enzyme engineering, and scalability, there are some of the gaps in the existing

literature that we need to fill to move this field forward. Since there are fresh approaches, and inventions

like bioreactor, photobiocatalysis, nanotechnology, researchers have a possibility to work out the more

effective and stable systems for PET and other plastics processes. If sustained growth and integrated

cooperation is made, microbial degradation can be a solution in the battle to fights plastic pollution and

enhance the world’s future.

Conclusion

Summary of Findings

The investigation of microbial degradation in light of increasing plastic pollution has been fruitful,

especially with respect to finding ways of biodegrading PETs. Possibilities of PET degradation have been

realized with the identification of PET degrading enzymes such as PETase and MHETase, which imply

that certain microorganisms have the specific ability to decompose PET to its monomers TPA and EG.

These findings are crucial steps toward creating long term solutions to the issue of dealing with plastic

waste.

Some of the conclusions that have been drawn from the study are the ways that affects the

efficiency of degradation of PET by microbes, the characteristics of the PET like its crystalline structure

and molecular weight, the environmental conditions and the properties of the microbial species. This has

been made possible by the engineering of enzymes with improved activity and stability within the

microbial degradation process, thus expanding the prospects of microbial degradation for greater

scalability.

But the studies also revealed some issues which are deserving of attention to make microbial

degradation popular and widespread. Some of these factors are the slow degradation process, the

impossibility of developing large- scale and cost- effective processes and the utilization of GMO products.

Still, enzyme engineering and synthetic biology as well as developments in various biotechnological

applications point to microbial degradation as a potential key component of future waste management

systems.

Implications for Policy, Research, and Industry

These findings apply to broad fields of policy, research and industry on a broad spectrum. As such, for

achieving the full optimization of microbial degradation for management of plastic waste, all the above

mentioned sectors are required to come into force.

Policy Implications

In the policy perspective, there is still a missing link, whereby governments must step forward to

develop policies that will encourage organizations to implement microbial degradation technologies. This

should be done through policy that supports research and development in this field through sponsorships,

grants and other incentives which firm wish to use microbial degradation processes. The regulatory bodies

should also set safety and environmental requirements that govern the application of genetically modified

microorganisms that their applications will not be a menace to the complexity and interrelations of original

ecosystems, and the earth’s bio-diversity.

Public awareness may also be created by governments with a view of informing the public about

the possibilities of microbial degradation as a solution to the management of plastic waste. Awareness

creation through the encouragement of public education might assist in the clarification of these

technologies especially where there is high consciousness of the impacts of plastic pollution. Furthermore,

cooperation and policy coordination of different countries are important because microbial degradation

technology is internationalized since the pollution of plastic waste is a worldwide problem.

Research Implications

Such research implications are enormous, and several lines that need to be pursued for further

study have been highlighted. It is, therefore, important to establish a better knowledge on the variants of

microorganisms that degrade PET in various settings. The extension of the search for new microbial

strains with higher degradative capacities would go a long way in boosting up the prospects of microbial

degradation technologies.

The other significant area of focus for research is the refinement and improvement of enzyme

engineering methods that will produce better PET degrading enzymes. The breakthroughs in protein

engineering synthetic biology and computational modeling could help in identification of new enzymes

with more activity, more stability and specificity. These measures could be supported by the studies

concerning with the design of bioreactors, the technique of photobiocatalysis, and nanotechnology, which

may help promote the efficiency of microbial degradation as well as enhance the scalability.

It is also necessary to collaborate with scientists from other disciplines, mostly in determining the

potential environmental consequences the utilization of engineered microorganisms for PET degradation

in the long run. The characteristics of these microbes in the context of natural systems, including the

effects that microbial degradation has on ecosystems and vice versa, will also have to be defined using

highly technical ecological research tools; so would risks and benefits associated with microbial

degradation.

Industry Implications

Thus, by focusing on microbial degradation technologies it appears to point on an importance of

developing and utilizing them in the industry. There are several industries that shall benefit from these

technologies including waste management and recycling firms, and biotechnology firms. Through

microbial degradation processes, industries will be able to avoid landfilling and incineration practices and

will help the government in promoting the concept of circular economy where PET waste will be

transformed into useful material.

The most important process to encourage microbial degradation technologies is the expansion of

Public-Private Partnership to provide those technologies in large amounts. On that basis, multiple sectors

that include the industry, academia, and government settings can work together to facilitate the

implementation of research outcomes that would in turn foster commercialization of products and services

to address the problem with plastic pollution.

Moreover, today industries are also can become important stakeholder in the development of the

research by offering the funds and the environment for testing newly created technologies. Thus, the close

collaboration between researchers and companies allows improving the existing microbial degradation

processes, bringing them to the new level of effectiveness, efficiency, and affordability.

Therefore, it is quite possible to consider microbial degradation of PET as one of the most

manageable ways for reducing the problem of plastic pollution and ensuring sustainability. But to fully

unlock its potency it is going to need combined efforts from policies, researchers, and industries. With

proper guidance towards the modern day problems and development based on the existing progress,

microbial degradation could make its way to become one of the essential and core subgroups of waste

management for the future of the planet earth.

References

1. Afshar, S. V., Boldrin, A., Astrup, T. F., Daugaard, A. E., & Hartmann, N. B. (2023). Degradation

of biodegradable plastics in waste management systems and the open environment: A critical

review.

Journal

Cleaner

Production,

140000.

2. DOI:10.1016/j.jclepro.2023.140000

3. Ali, S. S., Elsamahy, T., Al-Tohamy, R., Zhu, D., Mahmoud, Y. A. G., Koutra, E., ... & Sun, J.

(2021). Plastic wastes biodegradation: Mechanisms, challenges and future prospects. Science of

The Total Environment,780, 146590.

4. https://doi.org/10.1016/j.scitotenv.2021.146590

5. Bahl, S., Dolma, J., Singh, J. J., & Sehgal, S. (2021). Biodegradation of plastics: A state of the art

review. Materials Today: Proceedings, 39, 31-34. DOI:10.1016/j.matpr.2020.06.096

6. Barclay, A., & Acharya, K. R. (2023). Engineering Plastic Eating Enzymes Using Structural

Biology. Biomolecules, 13(9), 1407. https://doi.org/10.3390/biom13091407

7. Barrick, A., Champeau, O., Chatel, A., Manier, N., Northcott, G., & Tremblay, L. A. (2021). Plastic

additives: Challenges in ecotox hazard assessment. PeerJ, 9, e11300.

https://doi.org/10.7717/peerj.11300

8. Benavides Fernández, C. D., Guzmán Castillo, M. P., Quijano Pérez, S. A., & Carvajal Rodríguez,

9. L. V. (2022). Microbial degradation of polyethylene terephthalate: a systematic review. SN Applied

Sciences, 4(10), 263. DOI:10.1007/s42452-022-05143-4

10. Cai, Z., Li, M., Zhu, Z., Wang, X., Huang, Y., Li, T., Gong, H., & Yan, M. (2023). Biological

Degradation of Plastics and Microplastics: A Recent Perspective on Associated Mechanisms

and Influencing Factors. Microorganisms, 11(7), 1661.

11. https://doi.org/10.3390/microorganisms11071661

12. Carmen, S. (2021). Microbial capability for the degradation of chemical additives present in

petroleum-based plastic products: A review on current status and perspectives. Journal of

Hazardous Materials, 402, 123534. https://doi.org/10.1016/j.jhazmat.2020.123534

13. Ghosh, K., & Jones, B. H. (2021). Roadmap to biodegradable plastics—Current state and research

needs. ACS Sustainable Chemistry & Engineering, 9(18), 6170–6187.

https://doi.org/10.1021/acssuschemeng.1c00801

14. He, Y., Deng, X., Jiang, L., Hao, L., Shi, Y., Lyu, M., ... & Wang, S. (2023). Current advances, challenges and strategies for

enhancing the biodegradation of plastic waste. Science of The Total Environment, 167850.

https://doi.org/10.1016/j.scitotenv.2023.167850

15. Iroegbu, A., Ray, S., Mbarane, V., Bordado, J., & Sardinha, J. (2021). Plastic pollution: A perspective on matters arising:

Challenges and opportunities. ACS Omega, 6(30), 19343– 19355. https://doi.org/10.1021/acsomega.1c02760

16. Joseph, T. M., Azat, S., Ahmadi, Z., Jazani, O. M., Esmaeili, A., Kianfar, E., ... & Thomas, S. (2024). Polyethylene terephthalate

(PET) recycling: a review. Case Studies in Chemical and Environmental Engineering, 100673.

https://doi.org/10.1016/j.cscee.2024.100673

17. Kassab, A., Al Nabhani, D., Mohanty, P., Pannier, C., & Ayoub, G. Y. (2023). Advancing plastic recycling: Challenges and

opportunities in the integration of 3d printing and distributed recycling

for

circular

economy.

Polymers,

15(19),

3881.

18. https://doi.org/10.3390/polym15193881

19. Kaushal, J., Khatri, M., & Arya, S. K. (2021). Recent insight into enzymatic degradation of plastics prevalent in the environment:

A mini-review. Cleaner Engineering and Technology, 2, 100083.

20. Khairul Anuar, N. F. S., Huyop, F., Ur-Rehman, G., Abdullah, F., Normi, Y. M., Sabullah, M. K., & Abdul Wahab, R. (2022).

An Overview into Polyethylene Terephthalate (PET) Hydrolases and Efforts in Tailoring Enzymes for Improved Plastic

Degradation. International journal of molecular sciences, 23(20), 12644.

21. https://doi.org/10.3390/ijms232012644

22. Kortsha, M. (2022, September 29). Plastic-eating enzyme could eliminate billions of tons of landfill waste. UT News.

https://news.utexas.edu/2022/04/27/plastic-eating-enzyme- could-eliminate-billions-of-tons-of-landfill-waste/

23. Kotova, I. B., Taktarova, Y. V., Tsavkelova, E. A., Egorova, M. A., Bubnov, I. A., Malakhova, D. V., ... & Bonch-

Osmolovskaya, E. A. (2021). Microbial degradation of plastics and approaches to make it more efficient. Microbiology, 90, 671-

701. DOI: https://doi.org/10.1134/S0026261721060084

24. Maurya, A., Bhattacharya, A., & Khare, S. K. (2020). Enzymatic Remediation of Polyethylene Terephthalate (PET)-Based

Polymers for Effective Management of Plastic Wastes: An

25. Overview. Frontiers in bioengineering and biotechnology, 8, 602325.

https://doi.org/10.3389/fbioe.2020.602325

26. Mohanan, N., Montazer, Z., Sharma, P. K., & Levin, D. B. (2020). Microbial and enzymatic

degradation of synthetic plastics. Frontiers in Microbiology, 11, 580709.

https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.580709/fu ll

27. Nikolaivits, E., Taxeidis, G., Gkountela, C., Vouyiouka, S., Maslak, V., Nikodinovic-Runic, J., &

Topakas, E. (2022). A polyesterase from the Antarctic bacterium Moraxella sp. degrades highly

crystalline synthetic polymers. Journal of Hazardous Materials, 434, 128900.

28. Qi, X., Ma, Y., Chang, H., Li, B., Ding, M., & Yuan, Y. (2021). Evaluation of PET Degradation

Using Artificial Microbial Consortia. Frontiers in microbiology, 12, 778828.

https://doi.org/10.3389/fmicb.2021.778828

29. Rangel-Buitrago, N. and Neal, W.J. (2023) ‘A geological perspective of plastic pollution’, Science

of The Total Environment, 893, p. 164867. doi:10.1016/j.scitotenv.2023.164867.

30. Raoufi, H., Taqwa, S., & Fagiryaar, F. (2023). Enzymatic Degradation of Polyethylene and

Polyethylene Terephthalate: A Mini Review. American Journal of Environment and Climate, 2(3),

41-50. DOI:10.54536/ajec.v2i3.1937

31. Rhodes, C. J. (2018). Plastic pollution and potential solutions. Science Progress, 101(3), 207-260.

https://doi.org/10.3184/003685018X15294876706211

32. Ru, J., Huo, Y., & Yang, Y. (2020). Microbial degradation and valorization of plastic wastes.

33. Frontiers in Microbiology, 11, 442.

34. Salinas, J., Carpena, V., Martínez-Gallardo, M. R., Segado, M., Estrella-González, M. J., Toribio,

35. J., Jurado, M. M., López-González, J. A., Suárez-Estrella, F., & López, M. J. (2023). Development

of plastic-degrading microbial consortia by induced selection in microcosms. Frontiers in

microbiology, 14, 1143769. https://doi.org/10.3389/fmicb.2023.1143769

36. Sharma, B., Shekhar, S., Sharma, S., & Jain, P. (2021). The paradigm in conversion of plastic

waste into value added materials. Cleaner Engineering and Technology, 4, 100254.

https://doi.org/10.1016/j.clet.2021.100254

37. Skariyachan, S., Taskeen, N., Kishore, A. P., & Krishna, B. V. (2022). Recent advances in plastic

degradation - From microbial consortia-based methods to data sciences and computational.

38. Yang, X. G., Wen, P. P., Yang, Y. F., Jia, P. P., Li, W. G., & Pei, D. S. (2023). Plastic

biodegradation by in vitro environmental microorganisms and in vivo gut microorganisms of

insects. Frontiers in microbiology, 13, 1001750. https://doi.org/10.3389/fmicb.2022.1001750

39. Yasin, N. M., Akkermans, S., & Van Impe, J. F. (2022). Enhancing the biodegradation of (bio)

plastic through pretreatments: A critical review. Waste Management, 150, 1-12.

https://doi.org/10.1016/j.wasman.2022.06.004

40. Yuan, J., Ma, J., Sun, Y., Zhou, T., Zhao, Y., & Yu, F. (2020). Microbial degradation and other

environmental aspects of microplastics/plastics. Science of the Total Environment, 715, 136968.

https://doi.org/10.1016/j.scitotenv.2020.136968

41. Zhang, Y., Pedersen, J. N., Eser, B. E., & Guo, Z. (2022). Biodegradation of polyethylene and

polystyrene: From microbial deterioration to enzyme discovery. Biotechnology Advances, 60,

107991. https://doi.org/10.1016/j.biotechadv.2022.107991

Appendices

PRISMA Diagram

Microbial degradation of Polyethylene Terephthalate (PET)

Students also viewed