Perfringens Agar Base is a base medium that allows the enumeration of Clostridium perfringens from food samples.
As a base medium, Perfringens Agar Base can have several supplementary and selective agents added to increase selectivity.
The addition of Eye Yolk Emulsion (BM0140) allows the detection of lecithinase activity as precipitates are formed by C. perfringens. The addition of D-cycloserine (LS0023) can be used to inhibit other facultative anaerobes, as used in Tryptose-Sulphite-Cycloserine (TSC) agar. (1&2)
Alternately, kanamycin and polymyxin B (LS0025) can be used to inhibit other coliforms generally found in food samples, as used in Shahidi-Ferguson Perfringens (SFP) agar.(3)
The tryptose and soy peptone provide the required nitrogen, carbon and minerals.
Yeast extract provide the essential vitamins, including the vitamin B group, needed for growth.
The ferric ammonium citrate and sodium metabisulphite allows the reduction of sulphites to hydrogen sulphide by C. perfringens, which produces black colonies.
References
(1) ISO- 7937:2004. Microbiology of food and animal feeding stuffs- Horizontal method for the enumeration of Clostridium perfringens – Colony count technique
(2) Harmon, S.M., Kauttar, D.A. and Peeler, J.T. 1971. Improved Medium for Enumeration of Clostridium perfringens. Appl. Microbiol. 22:688-692.
(3) Shahidi S. A. and Ferguson A. R. 1971 New Quantitative, Qualitative, and Confirmatory Media for Rapid Analysis of Food for Clostridium perfringens. Appl. Microbiol. 21:500-506