HiMedia – M1569_HiCrome™ M-Lauryl Sulphate Agar

Principle and Interpretation
HiCrome™ M-Lauryl Sulphate Agar is a modification of the Lauryl Tryptose Broth, formulated by Mallman and Darby, (1). This chromogenic medium is recommended for the presumptive identification and differentiation of Escherichia coli and other coliforms by a single membrane filtration technique (2, 3). The incorporation of chromogen X-glucuronide and the dye phenol red favours the differentiation of E.coli and other coliforms on the basis of colour. Peptone provide nitrogenous and carbonaceous compounds, long chain amino acids and other essential growth nutrients to the organisms. Yeast extract serves as a source of vitamins especially group B vitamins. Lactose acts as a source of fermentable sugar while sodium lauryl sulphate inhibits gram positive organisms. The enzyme b-D-glucuronidase produced by E.coli, cleaves X-glucuronide, imparting a green colour to the colonies. Lactose fermentation is detected by phenol red indicator. Other lactose fermentors not possesing b-DGlucuronidase enzyme will show yellow colonies, whereas lactose non-fermentors will exhibit pink coloured colonies.

原理與解釋
HiCrome™M-Lauryl Sulphate Agar是Lauryl Tryptose的改良劑 由Mallman和Darby制定的肉湯，（1）。推薦這種顯色培養基用於通過單一膜過濾技術推測鑑定和分化大腸桿菌和其他大腸桿菌（2,3）。色原X-葡糖苷酸和染料酚紅的摻入有利於基於顏色區分大腸桿菌和其他大腸桿菌。 蛋白腖為生物提供含氮和含碳化合物，長鏈氨基酸和其他必需的生長營養素。酵母提取物是維生素的來源，尤其是B族維生素。乳糖作為可發酵糖的來源，而十二烷基硫酸鈉抑制革蘭氏陽性生物。由大腸桿菌產生的酶b-D-葡醣醛酸糖苷酶切割X-葡糖苷酸，從而產生 殖民地的綠色。通過酚紅指示劑檢測乳糖發酵。不具有b​​-DGlucuronidase酶的其他乳糖發酵罐將顯示黃色菌落，而乳糖非發酵物將顯示粉紅色菌落。