Biochemical Test Results In Depth

Question 1

Carbohydrate Fermentation Tests

Answer 1

• Determines utilization of carbohydrates
• Uses red pH indicator
• (+) for acid production= yellow broth
• (+) for CO2 production= bubble in durham tube

Question 2

TSI agar slant

Answer 2

• if butt turns yellow, ONLY glucose is used.
• if butt and slant trun yellow lactose and/or sucrose is used.
• cracks and lifting of agar= CO2 production
• uses phenol red

Question 3

Starch Hydrolysis Test

Answer 3

-uses starch agar
-looks for amylase activity, if present hydrolysis of starch happens
-use iodine to cover surface
-if zone of clearing, bacteria hydrolyzed starch
-no zone of clearing, no starch hydrolysis

Question 4

motility test

Answer 4

-use semisolid agar
-add TTC, as bacteria grows, a red insoluable pigment forms (formazan)
-flairing growth=motile
-No flairing growth=nonmotile

Question 5

Urease test

Answer 5

• ability to hydrolyze urea, creates ammonia and CO2
• uses phenol red pH indicator
• (+) basic high pH = pink
• (-) no change/ or yellow coloration (acidic)

Question 6

DNase Test

Answer 6

• ability to hydrolyze DNA (test for exoenzyme DNase)
• (+) zone of clearing
• (-) No zone of clearning

Question 7

IMViC test (indole)

Answer 7

• uses SIM media
• looks for tryptophanase
• uses 1% tryptone broth
• add kovacs reagent to look for indole
• red/ pink ring forms if indole present

Question 8

IMViC test (methyl red)

Answer 8

• uses MR-VP broth
• looks for mixed acid fermentation
• use methyl red reagent
• (+) if broth is red (acidic)

Question 9

IMViC test (voges proskauer)

Answer 9

• use MR-VP broth
• looks for butandiol fermentation
• looks for expression of actoin
• add barrets reagents A (alpha napthol)
• and Barremnts reagent B (KOH)
• (+) red formation on top of broth

Question 10

Citrate test

Answer 10

• uses simmons citrate agar
• for gram negative enteric
• looks for expression of citrate permease
• if growth means citrate permease is used
• uses bromothymol blue pH indicator
• (+) media turns blue

Question 11

EMB plate

Answer 11

• only gram negative enteric grow
• looks for fermentation of lactose
• (+) deep purple colony with green metallic sheen

Question 12

MSA plate

Answer 12

• looks for mannitol fermentation
• (+) yellow coloration of media

Question 13

catalayse test

Answer 13

-looks for enzyme catalase
-uses hydrogen peroxide
- (+) if bubble appear

Question 14

oxidase test

Answer 14

-looks for cytochrome c (peripheral membrane protein)
- use tetramethy-p-phenylenediamine (TMPDA)
- If e- exchange with cytochrome c, then (+) dark purple/blue