HiMedia – M1300and1826 HiCrome™ Coliform Agar w/ SLS/ Coliform Broth w/ SLS

Principle and Interpretation
HiCrome™ Coliform Agar / Broth w/ SLS is a selective medium recommended for the simultaneous detection of Escherichia coli and total coliforms in water and food samples (5). Peptone special and Sodium pyruvate provides nitrogenous, carbonaceous, compounds, long chain amino acid and other essential growth nutrients. The phosphates buffer the medium well. The medium composition helps even the sublethally injured coliforms to grow rapidly. Sodium lauryl sulphate inhibits gram-positive organisms. The chromogenic mixture contains two chromogenic substrates. The enzyme b-galactosidase produced by coliforms cleaves one chromogen, resulting in the salmon to red colouration of coliform colonies. The enzyme b -glucuronidase produced by E. coli, cleaves X-glucuronide. E.coli forms dark blue to violet coloured colonies due to cleavage of both the chromogens (1, 3, 4). The addition of L-Tryptophan improves the indole reaction, thereby increasing detection reliability in combination with the two chromogens. In M1826 chromogenic substrate in the medium help to detect b -glucuronidase positive E. coli. Other gram negative bacteria forms colourless colonies, except some organisms which are b-glucuronidase positive. b-glucuronidase positive organisms gives light blue to turquoise colonies. GUD is present in 94–96% of E. coli strains and in some Salmonella, Shigella and Yersinia spp (2). To confirm E. coli, add a drop of Kovac’s reagent (R008) on the dark-blue to violet colony/Blue colour broth. Formation of cherry-red colour indicates positive reaction.

原理與解釋
HiCrome™Coliform Agar / Broth w / SLS是一種選擇性培養基，推薦用於同時檢測水和食物樣品中的大腸桿菌和總大腸菌群（5）。蛋白腖和丙酮酸鈉提供含氮，含碳，化合物，長鏈氨基酸和其他必需的生長營養素。磷酸鹽緩衝介質。中等成分有幫助即使是亞致死受傷的大腸菌也會迅速生長。十二烷基硫酸鈉抑制革蘭氏陽性菌。 顯色混合物含有兩種生色底物。由大腸桿菌產生的酶β-半乳糖苷酶切割一種色原體，導致鮭魚染成大腸菌落的紅色。由大腸桿菌產生的酶β-葡醣醛酸酶切割X-葡糖苷酸。由於兩種色原體的切割，大腸桿菌形成深藍色至紫色的菌落（1,3,4）。 L-色氨酸的添加改善了吲哚反應，從而提高了與兩種色原體組合的檢測可靠性。在M1826培養基中的生色底物有助於檢測b-葡醣醛酸酶陽性大腸桿菌。除了一些β-葡萄醣醛酸酶陽性的生物外，其他革蘭氏陰性細菌形成無色菌落。 β-葡萄醣醛酸酶陽性生物體給予淺藍色至綠松石菌落。 GUD存在於94-96％的大腸桿菌菌株和一些沙門氏菌，志賀氏菌和耶爾森氏菌中（2）。為了確認大腸桿菌，在深藍色至紫色菌落/藍色肉湯上加入一滴Kovac試劑（R008）。櫻桃紅色的形成表明陽性反應。