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Letheen agar modified is intended for use in the isolation of microorganisms from cosmetics. The casein peptone, meat peptone, beef extract and yeast extract act as carbon, nitrogen and vitamin sources in this medium. Glucose is a fermentable carbohydrate. Sodium chloride maintains the osmotic balance of the medium. The sodium bisulfite, lecithin and polysorbate 80 inactivates quaternary ammonium compounds. Polysorbate 80 neutralises phenols, formalin, hexachlorophene, and in combination with the lecithin, ethanol. -
Lysine iron agar is a differential medium for the detection of Salmonella spp. and other enteric pathogens on the basis of lysine decarboxylase and hydrogen sulphide production. Lysine iron agar was originally developed by Edwards and Fife(1) for Salmonella arizonae detection. The peptone and yeast extract provides the required nitrogen, carbon and vitamins. Glucose is a fermentable carbohydrate. L-lysine is used to detect lysine decarboxylase and lysine deaminase enzymes. Sodium thiosulphate is reduced to hydrogen sulphide which is detected by the ferric citrate indicator. Sodium chloride maintains the osmotic balance. Bromocresol purple is a pH indicator. For use the medium is inoculated using a pure culture of the test organism which should be smeared onto the surface of the slope and stabbed into the butt of the medium. For details of the many reactions that may arise during the use of this medium reference should be made to one of the many standard textbooks.
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O-F Medium is used for the determination of oxidative and fermentative metabolism of carbohydrates by Gram-negative bacilli (1). This is on the basis of the acid reaction in either the open or closed system that has been covered with sterile paraffin oil. Changes in the covered agar are considered to be due to true fermentation, while changes in the open tubes are due to the oxidative utilization of the carbohydrate present. O-F Base Medium requires the addition of the specific carbohydrate being investigated. The enzymatic digest of casein provides the required nitrogen, carbon and vitamins in the media. Sodium chloride maintains the osmotic balance. Di-potassium hydrogen phosphate acts as a buffer and bromothymol blue is a pH indicator. The agar is a solidifying agent. Reference (1) Hugh, R. and Leifson, E.J. 1953. Bacteriol. 66:24-26.
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Potato dextrose agar is recommended for the detection and enumeration of yeasts and moulds in food and dairy products.It can also be used for the cultivation of fungi although with the prolonged incubation necessary cultures may become overgrown by bacteria. The low pH (5.6) suppresses the growth of most bacteria and the low mineral content ensures good pigment production by fungi where appropriate. This medium meets the requirements of the Harmonised USP/EP/JP.(1,2&3) REFERENCES (1) United States Pharmacopeial Convention. 2007. The United States pharmacopeia, 31st ed., Amended Chapters 61, 62, 111. The United States Pharmacopeial Convention, Rockville, MD. (2) Directorate for the Quality of Medicines of the Council of Europe (EDQM). 2007. The European Pharmacopoeia, Amended Chapters 2.6.12, 2.6.13, 5.1.4, Council of Europe, 67075 Strasbourg Cedex, France. (3) Japanese Pharmacopoeia. 2007. Society of Japanese Pharmacopoeia. Amended Chapters 35.1, 35.2, 7. The Minister of Health, Labor, and Welfare.
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Tryptone yeast extract salts (TYES) agar is a culture medium that can be used as the primary isolation medium for Flavobacterium columnare (1) and F. psychrophilum. Growth of Flavobacterium spp. requires a culture media with a lower nutrient content than that used in general-purpose mediums such as brain heart infusion agar andtryptone soya agar. The tryptone and yeast extract provide the required carbon, nitrogen and vitamins. Calcium chloride and magnesium sulphate provide the required minerals. Agar is a solidifying agent.
