Term
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Definition
| one that contains substances that areihibitory for many microorganisms, but allows the growth of some category or class of organisms. The inhibitory substance selectsfor growth of the desired type of orgamism(s). |
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Term
| low pH favors ____ while inhibiting most _______ |
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Definition
| condition favors growth of fungi while inhibiting most bacteria |
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Term
| the presence of high salt concenrations favors ____ while inhibiting most other bacterial species. |
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Definition
| This environment favors the growth of Staphylcoccus species while inhibiting most otherbacterial species. |
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Term
| What is the purpose of enrichment methods? |
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Definition
| a method of selective plating - it gives the dsired species a significant competitive advantagethrough the production of a substrate that the species can use effectively. For example, lactose in the medium facors lactose fermenters. Lactic acid, on the other hand, favors Proprionibacterium species over other species that may be present in a mixed culture. |
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Term
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Definition
| a commonly used selective medium (eosin-methylene blue) agar. Selects for gram negative bacteria (which can grow in the presence of bile salts/the two dyes), or gram positive organisms of intestinal origin. |
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Term
| What are two ways to select for types of organisms |
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Definition
| using inhibitory substances (i.e. low pH, high salt) or enrichment methods (lactose, lactic acid) |
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