Microbiology Lab: Biochemical Tests for Microbe Identification

This set covers biochemical laboratory tests including Hydrogen Sulfide, Carbohydrate Fermentation, and the IMViC series used for microbial identification.

Hydrogen Sulfide Test

A test designed to identify microbes that possess enzymes to break down sulfur and produce hydrogen sulfide gas.

Ferric Sulfide

The black precipitate formed during a Hydrogen Sulfide Test, serving as an indicator of hydrogen sulfide gas production, specifically seen in C. freundii.

SIM Deep Tubes

The specific media tubes used in the Hydrogen Sulfide Test where microbes are inoculated via the stab method.

Carbohydrate Fermentation Test

A procedure used to identify microbes that have enzymes to break down sugar to produce by-products such as acids and gases.

Phenol Red

The indicator used in carbohydrate fermentation tubes (PRGB and PRLB) that changes color to signify the presence of acid.

PRGB and PRLB Tubes

Tubes used for glucose and lactose fermentation tests; according to the results, E. coli, E. aerogenes, and C. freundii all produce acid and gas in these media.

IMViC Test

A series of four biochemical tests (Indole, MR, VP, and Citrate) used to identify microbes within the family Enterobacteriacaea.

Indole (IMViC)

A test for an enzyme that can produce indole, performed using a stab needle inoculation.

MR (Methyl Red)

An IMViC test that detects the presence of acids produced after the breakdown of sugar.

VP (Voges-Proskauer)

An IMViC test used to identify the presence of acetoin after the breakdown of sugar.

Citrate (IMViC)

A test that identifies microbes processing citrate by checking for the production of Sodium Carbonate; it is inoculated using a zig-zag pattern with a loop.