Casein Hydrolysis Test- Principle, Procedure, Results


Casein hydrolysis test is a biochemical test used to determine the ability of bacteria to synthesize caseinase enzyme. Caseinase is an extracellular proteolytic enzyme that can hydrolyze casein, the main protein in milk. Casein hydrolysis test is also known as skim milk agar test or casein test.

Casein hydrolysis test is based on the observation that bacteria that produce caseinase can degrade casein in the culture medium, resulting in a clear zone around the bacterial growth. Bacteria that do not produce caseinase cannot degrade casein and do not produce a clear zone.

Casein hydrolysis test is useful for differentiating bacteria based on their ability to produce caseinase. Some bacteria that can hydrolyze casein are Bacillus subtilis, Bacillus cereus, Serratia marcescens, Pseudomonas aeruginosa, Lactococcus lactis, Streptomyces spp., and Actinomadura spp. Some bacteria that cannot hydrolyze casein are Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pyogenes.

Casein hydrolysis test can be applied in various fields such as microbiology, food science, dairy industry, and biotechnology. It can help in the identification of bacteria isolated from milk and milk products, differentiation of enteric bacteria and members of Bacillaceae, and characterization of actinomycetes. It can also help in the screening of potential producers of caseinase for industrial applications such as cheese making, detergent production, and waste management.