microbiology lab days 5 and 6 part 3 (biochemical assay, fermentation, beta galactosidase, onpg, TSI

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What is the enzyme catalase used for?

to protect bacteria from free radicals like hydrogen peroxide, superoxide, etc.
what is the principle of the catalase activity test?

some bacteria produce enzyme called catalase to protect themselves from free radicals like H2O2 and superoxide
what must one do in order to see if there is catalase acitivity within a culture?

add 3% hydrogen peroxide to the culture and if gas bubbles arise, the bacteria produce catalase
if you add 3% h2O2 to a bacterial culture and no gas bubbles form, what does this mean?

there is no catalase activity in this culture
What chemical reaction occurs when you add h2O2 to a culture of bacteria that produce catalase?

the H2O2 is broken down by catalase into H2O and O2.
what is a positive test for the catalase activity test?

bubbles forming
what do bacteria use coagulase for?

to form a fibrin clot around themselves to protect against the host's defenses
What chemicals are anti-coagulants?

citrate and EDTA
Citrate and EDTA are __-_____

anti-coagulants
what is a positive test for the coagulase tesst?

clotting is present
what is a negative test for the coagulase test?

no clotting in 4 hrs
____ and ___ are added usually as an _____ to prevent clotting by other mechanism

citrate and EDTA are added usually as anticoagulant
in the coagulase test, results can be determined within ___ ___

4 hrs
what does dnase do?

dnase is an enzyme produced by some bacteria that degrades host DNA and increase the pathogenicity
what is a positive test in DNase test?

a zone of clearing around the colony indicates +ve DNase activity

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microbiology lab days 5 and 6 part 3 (biochemical assay, fermentation, beta galactosidase, onpg, TSI

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microbiology lab days 5 and 6 part 4 (biochemical assay, fermentation, beta galactosidase, onpg, TSI

Updated

2013-11-03T23:48:47Z

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