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Long and Hammer agar is for the detection of aerobic microorganisms in fish and fish products. This media is recommended for the determination of spoilage organisms in fresh and lightly preserved seafoods. (1) The proteose peptone acts as a nitrogen, carbon and vitamin source. Gelatine is a protein source and solidifying agent. Sodium chloride maintains the osmotic balance and di-potassium hydrogen phosphate is a buffer. 1) Nordic Committee on Food Analysis. (2006) Aerobic count and specific spoilage organisms in fish and fish products. NMKL Method No 184 -
Lowenstein-Jensen medium is based on the original formulation of Lowenstein that was subsequently modified by Jensen. It is used with fresh egg and glycerol for the isolation and presumptive identification of Mycobacterium spp., particularly Mycobacterium tuberculosis, from clinical samples. L-Asparagine and Potato starch are sources of nitrogen and vitamins in the medium. Potassium hydrogen phosphate and magnesium sulphate enhance organism growth and act as buffers. Sodium citrate and malachite green are selective agents that have inhibitory effects on organisms other than the mycobacteria. Malachite green is also incorporated into the medium to provide a colour contrast between the colonies and the medium. The required addition of egg emulsion provides the fatty acids and protein required for the metabolism of mycobacteria. Glycerol is also added which is said to enhance the growth of Mycobacterium tuberculosis however other strains of mycobacteria, particularly Mycobacterium bovis, may be inhibited by its presence. Subsequently, sodium pyruvate (12.5 g/600ml) may be used as an alternative to glycerol to encourage the growth of Mycobacterium bovis.
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MacConkey agar No. 3 is a selective medium primarily for the isolation of Enterobacteriacae from waters and sewage. This media differs from the original MacConkey formulation in that as well as bile salts, crystal violet has been included as an additional selective agent. This has the effect of inhibiting Gram-positive organisms. The peptone acts as a nitrogen, carbon and vitamin source. Sodium chloride maintains osmotic balance. Lactose is a carbohydrate and during its fermentation causes a confined pH drop around the bacterial colony. This causes a colour change in the pH indicator, neutral red and bile precipitation.
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KM0124 MacConkey Agar with Salt is a selective medium for the isolation and differentiation of bile tolerant Gram-negative (enteric) and Gram-positive (staphylococci and enterococci) organisms in all areas of bacteriology. MacConkey Agar with Salt is based on the formulation by MacConkey in 1900. Staphylococcus and Enterococcus spp. are able to grow due to the omission of crystal violet from this formulation. This medium is recommended by the World Health Organisation and the Department of Health for the bacteriological examination of water, and KM0124 is recommended as a differential primary isolation media by the UK Standards for Microbiology Investigations.
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MacConkey Agar without Salt and Crystal Violet, based on the formulation by Rappaport and Henig, is a differential medium for the isolation and differentiation of lactose and non-lactose fermenting enteric bacteria while also restricting the swarming of Proteus species. KM0011 is recommended as a differential primary isolation media by the UK Standards for Microbiology Investigations, The Microbiology of Drinking Water and tested in accordance with ISO 11133:2014. Related Supplements : LS0189 Cefotaxime Supplement (1mg/L)
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A selective medium for the enrichment of Enterobacteriaceae and the detection of Escherichia coli in pharmaceutical products. The inclusion of bromocresol purple indicator makes the colour change caused by acid production from the fermentation of lactose easy to read with gas formation. The presence of ox bile helps to suppress the growth of Gram-positive and non-enteric bacterial species. This formulation complies with the Harmonized USP/EP/JP. Nitrogen is supplied by the gelatin peptone whilst lactose serves as the fermentable carbohydrate source. Oxbile is the selective agent helping to suppress Gram-positive organisms and bromocresol purple detects the pH change as a result of the fermentation of lactose.
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Malt extract is sourced from hydrolyzed vegetal protein. Due to the high concentration of carbohydrate malt extract is particularly suited for the cultivation of yeasts and moulds especially in contaminated dairy products. In microbiological culture media it provides a source of nutrients, protein, and carbon.
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Malt extract agar is used for the detection, isolation and enumeration yeasts and moulds. The high carbohydrate content of the medium ensures rapid growth of yeasts and moulds. Malt extract and mycological peptone provide the carbon, protein and nutrient sources required by the organisms. The acidic nature of this medium allows for optimal growth of moulds and yeasts while restricting bacterial growth. Malt extract agar can also be used for the cultivation of fungi, although with the prolonged incubation necessary, cultures may become overgrown by bacteria. The selectivity of the medium can be increased by lowering the pH to 3.5-4.0 or by the addition of selective agents such as chloramphenicol. Related Supplements : LS0050 Chloramphenicol Selective Supplement
