Lab Exam Review 2-BM-W14 d08da581a0406a00b0ae07e205e8436e copy 24 PDF

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Lab practice review with answers...

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The Enteric Bacilli Exercise 16.12

This is SIM medium

1) What does SIM stand for? 2) What general group of bacteria is this medium used to differentiate? 3) Why is the medium in the tube cloudy? 4) What makes the top of one of the tubes red? 5) What makes the medium in one of the tubes black? 6) What other medium did we use in the lab to test for H2S production? 7) What nonpathogenic enteric did we study produces H2S?

BIOL225'–'Basic'Microbiology'–'Lab'Exam'2'Review'Sheets'–'Page'53'

Answers – Ex. 16.12

1) SIM = Sulfide, Indole, Motility 2) This medium is used in the identification of the enteric bacteria 3) The cloudiness indicates that the test bacterium is motile (and has moved through the medium as it has grown). 4) The redness in the liquid on the top of the tube is due to a reaction with Kovac’s reagent added to detect the presence of indole. Indole is a breakdown product of the amino acid tryptophan. The red color is a positive indole reaction. 5) The blackness is due to the bacterium producing hydrogen sulfide gas (H2S) which reacts with the iron compounds in the medium to produce a black color. 6) TSI (Triple sugar Iron) medium can also test for H2S production. 7) Proteus vulgaris or Proteus mirabilis produces H2S.

BIOL225'–'Basic'Microbiology'–'Lab'Exam'2'Review'Sheets'–'Page'54'...