ONPG test principles,Composition and Cultural response

Ortho-nitrophenyl-b-D-galactopyranoside abbreviated ONPG is a microbiological biochemical test used for the rapid detection of  the enzyme b-galactosidase activity in some microorganisms, especially those late lactose fermenters (cryptic lactose fermenters). Lactose fermentation by microorganisms requires a couple of enzymes…


Bile solubility test for Streptococcus pneumoniae

The bile solubility testing is microbiology biochemical test that helps to differentiate bile and bile salts soluble organism like Streptococcus pneumoniae from other insoluble bile and bile salt alpha haemolytic  streptococci such as streptococcus viridans. Principle of Bile…


Bacteria motility test (Hanging drop technique)

The idea of knowing whether a suspected organism is motile or not can be of great use in bacteria identification knowing that not all bacteria are motile meaning not all bacteria possesses flagella. Motility is one characteristic used…

Catalase Test Staph Strep

Biochemical catalase test principle and interpretations (All catalase positive organism)

The Catalase biochemical test is used to differentiate those bacteria that are able to produce the enzyme catalase from non catalase producing bacteria.This test is mostly used for the differentiation of Catalase postive staphylococci from catalase negative streptococci …

Oxidase test

Bacteria Oxidase Biochemical test (Fresh and Test Strip method)

The oxidase biochemical test was originally devised to identify Neisseria species, but later was used to separate the Pseudomonadaceae from the oxidase-negative Enterobacteriaceae.This test identifies organisms that produce the enzyme cytochrome oxidase that participates in the electron transport…


Simmons’ citrate agar Principles,composition and colony characteristics

Simmons’ citrate agar is differential growth media recommended for  gram-negative bacteria or members Enterobacteriaceae  on the basis of citrate utilization.That is,useful for organisms that uses citrate as a carbon and source of energy. It is also defined as…

Motility indole urea test MLTGEEKS

Motility Indole Urea Principle, Composition, Preparation and Colony Characteristics

Abbreviated (MIU), Motility Indole Urea Medium base is used for the differentiation of Enterobacteriaceae. This medium is based on motility, urease and indole production. This medium contains peptones that provide carbon and nitrogen required for growth of bacteria….

Acetate utilization test MLTGEEKS

Acetate differential Agar principle and interpretation of test

Trabulsi and Ewing first formulated acetate Differential Agar. Tatum, Ewing and Weaver later on modified the medium by replacing sodium citrate by sodium acetate, which enables the differentiation of Shigella species from Escherichia coli. Organic acids have been…