Bio chem Quiz 1
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Starch (amylase) hydrolysis test
Tests if the bacteria has a exoenzyme (a enzyme that leaves the cell to break down big molecules like starch) amylase.
Once the bacteria has grown but grams iodine
positive reaction there will be a clearing around the growth (because it ate the starch)
Negative is no clearing around it once you add the iodine.
Casein is what makes milk opaque
This test tests for bacteria that release a exoenzyme caseinase (breaks down the casein in the culture)
A postive reaction will have clearing around the bacterial growth (because it will break down the casein in the milk agar)
Negative willl have no clearing around the bacterial growth.
Indole Test (tryptophan test)
This tests to see if the bacteria create tryptophanase that is able to break down tryptophan.
Once the broth has grown add 10 drops of kovac's reagant. The bacteria that does this uses pyruvate and ammonia as food.
If it's positive there will be a cherry red ring at the top of the tube
Negative reaction will have a green or yellow ring
Some enteric bacteria have a enzyme called urease that breaks down urea into CO2 and ammonia.
Phenol red is also used in it as a pH indicator red to yellow is a acidic 6.8pH or lower bright pink is 8.1pH or higher
A positive result is bright pink a negative result is yellow or beige (beige meaning medium)
Catalase production test
aerobic, facultative anaerobic and aerotolerant bacteria have protective enzymwa that reduce O2 toxicity by converting these derivatives to less harmful products
this test tests for the presense of catalase
Positive is if bubbles are produced
negative is if no bubbles are produced
This tests for the abiltiy for bacteria to produce cytochrome oxidase
Positive if it turns blue
Negative if it doesn't turn a color
Bio chem Quiz 1
notecards for biochem test part 1 quiz 1