SKU: sku-2229
For selective isolation and identification of Salmonellae. SELECTIVE LYSINE AGAR is used for selective isolation and identification of Salmonellae. This medium is originally described by ‘Downes’ is recommended by AOAC, APHA and FDA for the isolation and identification of Salmonellae in foods. The method is defined by AOAC, is hydrophobic grid membrane filter method where membrane filters are used containing hydrophobic lines, printed in a grid pattern, that serve as barrier to the spread of colonies from one area of the filter to another. Medium contains Peptic digest of animal tissue, Yeast extract provide nitrogen compounds, sulphur, vitamin B complex and other essential growth nutrients. Dextrose serves as an carbohydrate energy source. Bromo cresol purple is the pH indicator that changes from purple to yellow at acidic pH. Microorganism Salmonella, which are able to decarboxylate lysine, reverse this acid reaction and form blue - green, blue or purple colonies. Bile salts mixture and Sulphapyridine inhibit gram-positive organisms. Food sample is processed and suspended in a general enrichment broth and incubated for 18 to 24 hours at 35-37°C and then subjected to selective enrichment procedures in broth media. Prepare the aliquots through a selective hydrophobic grid membrane filter and place the aliquots for 6 - 8 hours for incubation period at 35-37°C. The filter is then placed on the surface of a plate of Selective Lysine Agar, which has been pre-dried to eliminate excess surface moisture. Air bubbles between the filter and agar surfaces must be avoided. For the confirmation of microorganism, second filter is similarly placed onto a plate of Hektoen Enteric Agar (TM 121). However, plates of Selective Lysine Agar are being kept for incubation for 24 ± 2 hours at 43° ± 0.5°C.  
Product Code: 
TM 1084

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