This document discusses various biochemical tests used to identify bacteria, including: 1) IMViC tests (Indole, Methyl Red, Voges-Proskauer, Citrate) which use different reagents and media to detect metabolic byproducts and acid production. 2) Other tests like urease, oxidase, catalase which detect enzymes that break down substances like urea, produce color changes, or decompose hydrogen peroxide. 3) Additional tests for properties like coagulase production, hemolysis, hydrogen sulfide formation, and pigment production which can identify pathogenic bacteria.

1. Biochemical Tests
Principles
Reagents & Media
Procedures & Results

3. IMViC
x Indole - x Methyl Red -
– product of hydrolysis – pH indicator
of tryptophan – production of
– Reagent - (Ehrlichs) sufficient acidity
Para-dimethyl- from glucose
aminobenzaldehyde – Media- MR-VP
– (+) pink or red color broth
– (+) red - acid
– (-) yellow - alkaline

5. IMViC (2)
x Vogues Proskauer - x Citrate Utilization Test
– production of – citrate as a source
acetyl-methyl of Carbon
carbinol from – media :Simmon
glucose Citrate (SCA)
– media: MR-VP – (+) blue color
broth – (-) green color
– reagent: 40% KOH
– (+) production of an
eosin like color

7. Biochemical Tests (3)
x Urease Test - x Oxidase Test -
– Hydrolysis of urea – catalysis of Oxidase
by Proteus sp. through cytochrome
– media: by N. gonorrhea
Christensen’s urea – media: CAP
– (+) Pink color media – reagent: 1% para-
/hemolysis amino-dimethyl-
– (-) colorless aniline hydrochloride
– (+) black

9. Biochemical Tests (4)
x Catalase Test - x Coagulase Test -
– decomposition of – coagulation of
3% Hydrogen plasma with enzyme
peroxide coagulase by
– (+) rapid evolution pathogenic
of gas staphylococcus
– organisms: – media: Blood plasma
y(+) staphylococci – (+) clotting of plasma
y micrococci
y (-) streptococci

11. Biochemical Tests (5)
x Hemolysis test - x Hydrogen Sulfide
– destruction of RBC test -
– media : Blood agar – production of
plate Hydrogen sulfide
– (+) clearing zone – any media with
x Greig’s Test Fe
– hemolysis of – (+) black ppt.
sheep’s rbc x Pigment formation
– (+) El tor (-) vibrio – chromogens

13. Enzymes produced by bacteria:
x Constitutive - essential enzymes
x Adaptive - non-essential enzymes
x Intracellular
x Extracellular