Microbial Metabolism
Tionette
44-0245-00-01_rpt_isolation_of_individual_c.docxIsolation of Individual Colonies
Cynthia Alonzo, M.S. Version 42-0245-00-01
Lab Report Assistant
This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.
Questions A. Define the following:
Enriched Media:
Selective Media:
Differential Media:
Complex Media:
Synthetic Media:
Experiment
Isolation of Individual Colonies
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B. Why is it necessary to use a solid agar medium to obtain a pure culture of S. epidermidis?
C. Compare your L. acidophilus pour plates and spread plate. Which method do you think worked better to isolate individual colonies? Why?
D. What are the six qualities included in a description of colony morphology?
E. Describe the colony morphology seen on your S. epidermidis dish.
F. What is the difference between a viable and total count? What is the difference between direct and indirect counts?
G. What is a spectrophotometer? How is it used to enumerate microbes?
H. What is a hemocytometer? How is it used to enumerate microbes?
I. Define the following acronyms:
CFU
TNTC
TFTC
OD
J. When serial dilution is used to enumerate microbes in a real life application, such as in a water quality study, each dilution is plated on a series of dishes. The data from each dish (the number of CFUs) is pooled together and an average CFU per dish is generated for the dilution. It is this average, rather than the actual plate counts, that is used to calculate the final CFU/mL result.
Why do you think an average is used rather than the actual plate counts? Why might there be differences in the number of CFUs on each dish when they are grown from the same dilution?
