Discuss the relative value of broth and agar media in isolating bacteria from mixed cultures.

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Exercise 7
Questions
1. Define a culture medium.
2. Discuss some of the physical and chemical factors involved in the
composition, and in the preparation, of a culture medium.
Nutrient ingredients:
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pH and buffering:
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Heat (to reconstitute):
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Heat (to sterilize):
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Other:
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3. At what temperature does agar solidify?
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From Laboratory Manual & Workbook in Microbiology Applications to Patient Care (10th ed.). By
Josephine A. Morello, Verna Morton, Helen Eckel Mizer, and Paul A. Granato Copyright Š 2011 The McGrawHill Companies, Inc. Reprinted with permission of The McGraw-Hill Companies, Inc. BIO2071_Microbiology Laboratory
At what temperature does agar melt?
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4. What would happen to plates poured with agar that is too hot?
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Could they be used?
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5. What would happen to plates poured with agar that is too cool?
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Could they be used?
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6. Why are culture media sterilized before use?
7. Discuss the relative value of broth and agar media in isolating bacteria from
mixed cultures.