HiMedia – M1712 HiCrome™ Nickels and Leesment Medium

Principle and Interpretation
Lactic acid bacteria are widespread in nature and are best known for their activities in major food such as dairy, meat and vegetable products (1). Testing for lactic acid bacteria in dairy products may be useful for various reasons like evaluating lactic starter cultures; determining the cause of acid defects in milk products, controlling the quality of cured cheese, cultured milks and uncultured products containing added cultures (2). HiCrome™ Nickels and Leesment Medium is a modification of Modified Nickels and Leesment Medium formulated as per APHA (1) and is used for the enumeration of citrate-fermenting lactic acid bacteria using colony count technique at 25°C. Tryptone and yeast extract serve as carbon and nitrogen sources, long chain amino acids, vitamin B complex and other essential growth nutrients. Lactose and Glucose (Dextrose) are the carbohydrate source in the medium. X-gal differentiates between Lactococcus lactis subsp. lactis and Leuconostoc species. Lactococcus lactis subsp. lactis biovar diacetylactis colonies are white with a clear zone. Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris colonies are white without a clear zone. Leuconostoc species are blue, with or without a clear zone. HiCrome™ Nickels and Leesment Medium with the addition of HiCrome™ Nickels and Leesment Supplement (FD245) can be used for enumeration of Leuconostoc (1). Vancomycin acts as a supplement for the selective isolation of Leuconostoc from a mix flora of lactic acid bacteria. Sodium chloride maintains osmotic equilibrium and various salts provide essential ions.

原理與解釋
乳酸菌在自然界中廣泛存在，並且以其在主要食品（例如乳製品，肉類和蔬菜產品）中的活性而聞名（1）。乳製品中乳酸菌的測試可能有多種原因，例如評估乳酸發酵劑培養物;確定乳製品中酸缺陷的原因，控制醃製乾酪，培養乳和含有添加培養物的未培養產品的質量（2）。 HiCrome™鎳和Leesment Medium是根據APHA（1）配製的改性鎳和Leesment Medium的改進，用於在25°C下使用菌落計數技術計算檸檬酸鹽發酵乳酸菌。胰蛋白腖和酵母提取物作為碳源和氮源，長鏈氨基酸，維生素B複合物和其他必需的生長營養素。乳糖和葡萄糖（葡萄糖）是培養基中的碳水化合物來源。 X-gal區分乳酸乳球菌（Lactococcus lactis）亞種。乳酸和明串珠菌屬物種。乳酸乳球菌亞種。 lactis biovar diacetylactis菌落是白色的，具有清晰的區域。乳酸乳球菌亞種。乳酸和乳酸乳球菌亞種。 cremoris殖民地是白色的，沒有明確的區域。明串珠菌屬物種是藍色的，有或沒有明確的區域。 HiCrome™鎳和Leesment Medium添加了HiCrome™鎳和Leesment Supplement（FD245），可用於Leuconostoc（1）的計數。萬古黴素作為從乳酸菌混合菌群中選擇性分離明串珠菌的補充劑。氯化鈉保持滲透平衡，各種鹽提供必需離子。