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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. -
Primary Membrane Lactose Glucuronide Agar (mLGA) is used for the differentiation and enumeration of Escherichia coli and other coliforms through a single membrane filtration technique. The peptone and yeast extract provide the required nitrogen, carbon and vitamins. Sodium pyruvate protects injured cells enhancing recovery and growth of coliforms. Sodium lauryl sulphate is a selective agent that inhibits Gram-positive organisms. Lactose is a fermentable carbohydrate and phenol red is a pH indicator. Lactose fermentation will result in yellow colonies. X-glucuronide is a chromogenic substrate which can be cleaved by the enzyme ß-glucuronidase present in E. coli. This results in a blue colony, but in combination with lactose fermentations colonies will appear green. NB: Prepared plates stored at 28°C may show formation of surface crystals which will disappear when plates are warmed to >20°C Related Supplements :
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Recent developments in culture media have given rise to the use of chromogenic substrates as a means of differentiating bacteria particularly among the coliform group of organisms. This is one such medium and has been developed with the aim of simplifying the differentiation and presumptive identification of the main organisms usually found in Urinary Tract Infections (UTI). The peptone is the source of the required nitrogen, carbon and vitamins. Based on the traditional CLED medium, to prevent the swarming of Proteus spp., two chromogens are present in the medium. One allows the detection of enterococci giving rise to blue colonies whilst the second results in purple colonies of E. coli. Phenylalanine and tryptophan are also included as indicators of tryptophan deaminase activity producing brown colonies of Proteus spp. Related Supplements : SHS500 Sterile Horse Serum 500ml
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This is a selective medium for the isolation of Pseudomonas spp. primarily in food, water and environmental samples. Pseudomonas agar base is on Kings A medium which uses magnesium and potassium salts to enhance pigment production. The gelatine peptone and acid hydrolysed casein acts as a nitrogen, vitamins, and carbon source. Magnesium chloride and potassium sulphate promotes production of pyocyanin. The medium can be made selective for P. aeruginosa by the addition of Pseudomonas CN Supplement (LS0006). Alternatively, the medium can be made selective for Pseudomonas spp. generally by the addition of Pseudomonas CFC Selective Supplement (LS0026). The presence of blue/green or brown pigmentation or fluorescence is indicative of presumptive Pseudomonas spp. It should be noted however that further testing must be carried out to confirm the full identity of the organism.
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R2A agar is used for the enumeration and cultivation of bacteria from drinking water. R2A agar developed by Reasoner and Geldreich is a low nutrient medium that can used in pour plate, spread plate, and membrane filtration methods for heterotrophic plate counts. In combination with a lower incubation temperature and longer incubation period R2A agar stimulates the growth of stressed and chlorine-tolerant bacteria. Traditionally nutritionally rich media have been used for this purpose but these media support the growth of fast-growing bacteria and may suppress slow growing or stressed bacteria found in treated water. Enzymatic digest of casein, proteose peptone, acid hydrolysate of casein and yeast extract provide the required nitrogen, carbon and vitamins. Glucose is a fermentable carbohydrate. Dipotassium hydrogen phosphate is a buffering agent. Magnesium sulphate is a source of divalent cations and sulphate. Starch and sodium pyruvate aid in the recovery of stressed organisms.
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Rappaport-Vassiliadis (MSRV) Medium Semi-Solid is a modification of Rappaport-Vassiliadis Soy Broth for detecting motile Salmonella spp. in faeces and food products.[1] The original research on MSRV Medium revealed a semi-solid could be used as a rapid and sensitive test for isolating motile Salmonella spp. from food products following pre-enrichment or selective enrichment.[2] The semi-solid medium allows motility to be detected as halos of turbid growth around the original point of inoculation. The peptones are to provide vitamins, nutrients and nitrogen to encourage growth of Salmonella spp. The salt maintains the osmotic balance and potassium dihydrogen phosphate is a buffer for stabilising the pH of the medium. Malachite green is included as a selective agent that inhibits Gram-positive organisms and some Gram-negative organisms. References (1) ISO 6579-1:2017. Microbiology of the food chain – Horizontal method for the detection, enumeration and serotyping of Salmonella – Part 1: Detection of Salmonella spp. (2) De Smedt J.M., Bolderdikj R., Rappold H. and Lautenschlaeger D. 1986. Rapid Salmonella Detection in Foods by Motility Enrichment on a Modified Semi-Solid Rappaport-Vassiliadis Medium. J. Food Prot. 49:510-514
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Rappaport-Vassiliadis Soya Broth is used for the enrichment and selective isolation of Salmonella spp. This medium is a modification of the original formulation by Rappaport et al. and has been formulated to exploit the full characteristics of Salmonella spp. These characteristics include the ability to survive at relatively high osmotic pressure, to multiply at low pH values and greater resistance to malachite green. This formulation also has the correct amount of magnesium chloride as previous formulations did not take into account the volume of displacement caused by dissolving large amounts of magnesium chloride in water. This formulation has been shown to be superior to tetrathionate broth and selenite broth for the isolation of Salmonella spp. from meat products. Soya peptone provides the required carbon, nitrogen and vitamins. Potassium dihydrogen phosphate and di-potassium hydrogen phosphate act as buffers. Magnesium chloride raises the osmotic pressure in the medium. Malachite green is an inhibitory substance. NB: This formulation is very hygroscopic and will produce a slight exothermic reaction when mixed with water.
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Sabouraud Dextrose Agar is one of several media available for theisolation of yeasts and fungi suitable for use in all areas of mycology. Sabouraud Dextrose Agar is a modification of a medium originally described by Sabouraud. The tryptone and meat peptone provide the nitrogen and vitamins required for organism growth in Sabouraud Dextrose Agar. The high concentration of dextrose is included as an energy source and in tandem with the acidic pH (5.6) facilitates the growth of fungi whilst providing limited selective properties. Higher levels of selectivity can be achieved against bacterial species by the addition of chloramphenicol. NB: This is a basic medium only and contains no additional supplements. Related Supplements : LS0050 Chloramphenicol Selective Supplement
