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This medium is intended for the cultivation and enumeration (via the Miles and Misra technique) of Lactobacillus spp. from a variety of sources and can be used in conjunction with MRS Agar (KM0080). This medium is a modification on the formulation developed by de Man, Rogosa and Sharpe.(1) The peptones, beef extract, yeast extract provides the required carbon, nitrogen and vitamins in this medium. Glucose is a fermentable carbohydrate. Potassium phosphate is a buffering agent. Selectivity of the medium is achieved through the use of ammonium citrate and sodium acetate, inhibiting microorganisms such as streptococci and moulds. The magnesium sulphate, manganese sulphate and polysorbate 80 act as growth stimulants. The medium can be made more specific for lactobacilli generally by lowering the pH to between 5.0 and 5.5. This has the effect of inhibiting most streptococci that may otherwise grow on the medium and can be readily confused with lactobacilli. -
This medium is for the growth of fastidious anaerobes, particularly Bacteroides spp. Fastidious anaerobe broth is also suitable for anaerobic blood culture. The peptone and yeast extract provides the required carbon, nitrogen and vitamins. Haemin, vitamin k and L-cysteine HCl are growth factors required by some anaerobes. Sodium thioglycollate and L-cysteine HCl reduce the Eh of the medium and the agar helps maintain the Eh. Resazurin is a redox indicator and sodium chloride maintains the osmotic balance. NB: For best results it is recommended that the medium be heated in a boiling water bath, with the cap loosened, and then allowed to cool, with the cap tightened, immediately before use. The cap must be replaced on the container immediately after inoculation.
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Lauryl Tryptose Broth is a selective medium for the detection of coliforms in water and wastewater. This formulation is based on the Mallmann and Darby formulation. (1) The tryptone provides the required carbon, nitrogen and vitamins in this medium. Lactose is a fermentable carbohydrate. The sodium chloride maintains the osmotic balance whilst the dipotassium hydrogen phosphate and potassium hydrogen phosphate act as buffers. Sodium lauryl sulphate is a selective again used to inhibit non-coliforms. References (1) Mallmann, W. L. and Darby, C. W. 1941. Uses of a lauryl sulphate tryptose broth for the detection of coliform organisms. Am J. Public Health. 31:127
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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
