Lab report for Excellent Prof

Running Head: Experiment on factor favoring growth bacterial growth 1

Experiment on factor favoring growth bacterial growth8

Experiment on factor favoring growth bacterial growth.

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Introduction and purpose

For bacterial to grow it requires two different categories of theenvironment: Nutritional and physical environment. The two environmental factor are very important for any bacterial growth.

Physical factor includes PH, gaseous, temperature and PH requirements. Different bacteria adapt to different optimum temperature for their growth; for example Psychrophiles, reproduce well in temperature between -5 C to 20 C. mesophiles reproduce well in room temperature and body temperature i.e 20 C to 45 C. While those that reproduce well at a temperature high than 45 C are called thermophiles.

Water, carbon source, mineral, nitrogen and organic nutrients are aNutritional requirement for bacterial growth. Optimal growth conditions the environmental requirements for bacterial where they are reproduction is rapid and maximum.

In laboratory,this environment can be liquid, semisolid or solid media and are used for different purposes. When bacteria is placed in correct media it starts reproducing by simple reproduction method, binary fission, where bacterium splits into two copies if itself (daughter cells). Reproduction time for most bacteria is relatively small, for example, E. coli reproduce after 20 minutes under optimal conditions.

To get the number of bacterial after sometimes, then we use the following formula;

Y* 2^z where z=reproduction cycle and y= number or original cells.

The lag phase is the initial period where bacterial growth is reduced, log phase is the period where bacterial growth is doubling (exponential growth). The stationary phase is apoint where the number of bacterial reproduction is diminishing. Death phase is apoint where the rate of growth is less than thedeath rate of bacteria.

Fig 1; Bacteria growth phases

The number of bacteria grown in a liquid medium is determined by using aspectrophotometer to measure absorbance. A spectrophotometer measures the scattered light in the liquid media.

The purpose of this experiment is to develop growth curve of bacterial reproduction and to compare minimum and rich media of cell growth.

Materials

The following are required for the experiment; Micropipettors, one LB tube, three LB plates, one rack for Eppendorf tubes, disposable cell spreaders.

Methods

A. Growth curve

1 ml culture medium is transferred to spectrophotometer tube and then transferred to clean cuvette and measured the OD at awavelength of 595 nm.

Transfer bacterial cultures into an Eppendorf tube then calculate cell density. LB plates are alabel with A, B, C. On plate A spread 10 ul, on B spread 100 ul and C spread 100 ul of dilution. The plate was then incubated for 24 hours at 37 C. Data for both growth curve were aplot in one graph.

B. Comparison minimal and rich medium

The plates were labeled properly and each E. coli onto each plate using cell spreader and the plate was incubated at 37 C for 24 hours.

Results

The results of growth curve wererecorded in table 1 belowTable 1; Growth curve

0	2:10p	0.178	1.78*10^7	0.210	2.10*10^7
Group	Time	OD 37C	Cells/ml 37C	OD 25C	Cells/ml 25C
60 min	3:10p	0.512	5.12*10^7	0.215	2.15*10^7
80 min	3:30p	0.616	6.16*10^7	0.233	2.33*10^7
100 min	3:50P	0.888	0.88*10^7	0.264	2.64*10^7
120 min	4:10P	0.100	1.00*10^7	0.293	2.93*10^7
140 min	4:30P	0.059	5.69*10^7	0.232	2.32*10^7

The growth curve is a shown below;

The results of comparison were recorded in table 2 below

Table 2; comparison table

TA	Theoretical (Cell/ml)	Actual (cell/ml)
TA	2.42*10^7	2.42*10^7
2	1.23*10^8	3.7*10^8
3	1.04*10^8	3.8*10^8
4	2.02*10^8	4.3*10^8
5	2.33*10^8	4.4*10^8

The comparison chart is as below

Discussion

Cells incubated at 37 C reproduced rapidly at first (log phase) afterward it seems to be in stationary phase, then dead phase. The cell growth then becomes stationary and then log phase once again. The cells incubated at 25 C seems to be stationary in its reproduction for the entered period of study.

From the experiment temperature of 37 C is an optimal temperature of this bacterial reproduction. The cells increase exponentially at first because they have enough nutrients to consume and the conditions in the plates are favorable.

The cells number becomes stationary since there is lots of competition and some cell dies in the dead phase more than the one reproducing. When the population reaches acertain point, they begin increasing in number again.

The cells incubated in 25 C plate do not increase rapidly in number because the temperature is not optimal.

In all the plates the number of cell in rich media is always more than the one in minimal media.

Conclusion

It is noted that E. coli cell exhibits maximum growth at a temperature of 37 C and hence this is an optimal temperature for the bacteria to reproduce rapidly.

Under rich media, the bacteria reproduce to their maximum number.

Reference

Cooper, S. (2011). Bacterial growth and division. San Diego: Academic Press.

Koch, A. (2005). Bacterial growth and form. New York: Chapman & Hall.