microbiology lab days 5 and 6 part 5 (biochemical assay, fermentation, beta galactosidase, onpg, TSI
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what does superoxide dismutase do?
it catalyzes the destruction of superoxide
what do catalase and peroxidase do?
catalyze the destruction of H2O2
What is a postive oxidase test?
change from pink color to dark purple
What is a positive phenylalanine deaminase test?
What is phenylalanin deaminase?
an enzyme tht catalyzes the removal of the amino group from phenylalanine.
During the phenylalanine deaminase test, what is done to the medium once a bacterium has been incubated on it?
ferric chloride is added
what is a negative test for phenylalanine deaminase?
no color change to green
in the nitrate reduction test, if a non-fermenter yields gas and no red color, what does this mean?
Nitrate was reduced to N2 only
If the nitrate reduction test yields a red color after the addition of reagents A and B, what does this mean?
Nitrate was reduced to nitrite
in the nitrate reduction test, If zinc is added to the medium and the medium turns red, what does this mean?
nitrate was not reduced
in the nitrate reduction test, If one adds reagents A and B as well as zinc and no color change is observed, what does this mean?
nitrate reduced to ammonia or hydroxylamine
What is the principle of the nitrate reduction test?
bacteria that are able to reduce nitrate can produce a variety of metabolites (ammonia, nitrite, nitrogen gas, etc.) while some bacteria aren't able to reduce nitrate. These distinctions allow us to differentiate many different strains of bacteria
what molecules can nitrate be reduced to?
nitrite, nitrogen gas, ammonia, hydroxylamine
in the TSI agar test, if a red butt and red slant is observed, the bacterium cannot be from the ___________
What is cysteine desulfurase?
an enzyme that cleaves the sulfur atom from cysteine to form hydrogen sulfide gas