-
what is tsi agar used to detect?
presence of sugar fermentation, gas production and H2S production.
-
what does saccharolytic mean?
the term saccharolytic can be used to describe those microorganisms that are capable of breaking the glycosidic bonds within carbohydrates
-
how do you interpret the results of the TSI agar test?
Red butt/slant indicates alkalinity, yellow butt/slant indicates acidity, black deposits indicate presence of H2S, bubble at the bottom indicates gas production
-
what is the aim of the IMViC test?
to identify enteric bacteria
-
what are the four parts of the IMViC test?
indole test, methyl red test, Voges-proskauer test, citrate test
-
bacteria produce enzyme tryptophanase to hydrolyse an amino acid called tryptophan to a metabolic product called _____
indole
-
indole reacts with _____ _____ to give a color change
kovac's reagent
-
what does a positive indole test look like?
formation of red color layer on top
-
what is the principle of the methyl red test?
some microorganisms produce mixed acids which reduces pH to below 4 to cause a color change to red color (+ve test). other organisms produce less acids, not enough to produce color change, so appear yellow.
-
voges proskauer test detects which chemical?
acetoin
-
During the voges proskauer test, which reagent is added to the medium?
barritt's reagent that contains 40% KOH and 5% α-naphthol
-
how do you interpret the results of a Voges proskauer test?
+VP test: red color development within 15 min of addition of reagent
-VP test: no color change
-
what agar is used in the citrate test?
simmons citrate agar slant containing sodium citrate, ammonia, and bromothymol blue
-
Citrate utilization in the citrate test causes the pH of the medium to ____ because...
pH increases because there is a buildup of alkaline product formation, which causes a color change.
-
how do you interpret the results of the citrate test?
+ citrate test: color change from green to blue
-citrate test: color remains green
|
|