This document summarizes various biochemical tests used to identify bacteria, including: - Fermentation tests using Durham tubes to detect gas and acid production from carbohydrates. - The IMVIC series of tests (Indole, Methyl Red, Voges-Proskauer, Citrate) which identify metabolic pathways and substrate utilization through color changes. - Other common tests like catalase, coagulase, urease, and oxidase which detect enzymatic activity through production of gas or color changes. Students are assigned to prepare SIM, MRVP, and SCA media, inoculate bacterial samples, interpret test results using described reagents and expected color changes, and submit a write-

1. Principle, Reagents & Media
Procedures & End results
BIOCHEMICAL ACTIVITIES

3. BIOCHEMICAL ACTIVITIES OF BACTERIA:
Biochemical properties could be used as tools
of identification  demonstrate certain
metabolic activity of microbes
Example : Fermentation – durham tubes
 Carbohydrates, amino acids, organic
acids
 1. gases – Carbone dioxide, methane, hydrogen
 2. Acid production – use of indicators to detect
 Either acid or gas or both can be collected

4. IMVIC - INDOLE TEST
 Principle : product of hydrolysis of an amino acid
tryptophan
 Media – SIM (Sulfide Indole Motility)
 Reagent - (Ehrlich’s) Para-dimethyl-
aminobenzaldehyde
 Positive result :(+) pink or red color
 Negative Result : (-) absence of pink or red color

5. IMVIC - METHYL RED TEST
 Methyl red is a pH indicator
 Principle : production of sufficient acidity from
glucose
 Media- MR-VP broth
 (+) red - acid
 (-) yellow - alkaline

6. IMVIC - VOGUES PROSKAUER
• production of acetyl-methyl carbinol
from glucose
•media: MR-VP broth
•reagent: 40% KOH
•Positive (+) result = production of
an eosin like color

7. IMVIC - CITRATE UTILIZATION TEST
 Principle: utilizes citrate as a source of Carbon
 Media :Simmon Citrate (SCA)
 (+) blue color
 (--) green color

8. OTHER COMMON BIOCHEMICAL TESTS:
 Coagulase test
 Catalase test
 Urease test
 Hemolysis test
 Greig’s Test
 Oxidase Test
 Hydrogen Sulfide Test

9. ASSIGNMENT:
 Find the other biochemical Tests & tabulate
them based on:
 Working principle
 Reagents & Media
 Positive & Negative Results

10. WHAT TO DO?
 Place all your glassware in a plastic bag
 Autoclave 15 psi, 121 C, 15 minutes
 Wash , clean and dry
 Wrap and sterilize in the oven, 150 C, 45
minutes

11. MEDIA PREPARATION
 Prepare 200 ml each ( for the whole class)
 SIM
 MRVP
 SCA
 Dispense into 4 test tubes
1 tube SIM
 2 tubes MRVP
 1 tube SCA ( Slant )

12.  Inoculate with bacteria ( get from me )
 Incubate in incubator 48 hours
 Add the reagents ( from previous slides )
 Check results
 Make a one page write – up
 Submit