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17 Cards in this Set
- Front
- Back
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combination differential media
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combinations of ingredients put together to allow multiple biochemical determinations
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what kind of media is a SIM media?
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combination differential media
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what does SIM media test for?
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sulfur reduction, indole production, and motility --important characteristics for enterobacteriaceae
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MacConkey Agar
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isolates gram negative bacilli
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what do you do after MacConkey Agar?
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Kligler Iron Agar
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Kligler Iron Agar
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differentiation among gram negative bacilli because of its ability to detect glucose and lactose fermentation and sulfur reduction
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what does SIM medium test for?
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sulfur reduction, indole production, motility
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what does the SIM medium consist of?
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1. casein and animal tissue for amino acid
2. iron containing compound 3. sodium thiosulfate for sulfur |
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how can sulfur reduction to H2S be accomplished by bacteria?
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1. cysteine desulfurase catalyzes prtrefaction of amino acid cysteine to pyruvate
2. thiosulfate reductase catalyzes the reduction of sulfur. |
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what does it mean when there's black precipitate
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there was a reaction where the H2S combined with iron to form ferric sulfide.
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results is blackening of the medium
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sulfur reduction and a positive test
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results is no blackening
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no sulfur reduction and a negative reaciton
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how is indole production made possible?
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by the presence of tryptophan. bacteria with tryptophanase can hydrolyze tryptophan to pyruvate, ammonia, and indole
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how do you detect hydrolysis of tryptophan?
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with the addition of Kovac's reagent after a period of incubation
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results are red
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positive reaction and presence of tryptophanase.
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results are no red
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indole negative
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how do you determine motility in SIM medium
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by the reduced agar concentration and method of stab inoculation. motile organisms can move around the medium
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