Adams M R, Grubb S M, Hamer A, Clifford M N
Department of Microbiology, University of Surrey, Guildford, United Kingdom.
Appl Environ Microbiol. 1990 Jul;56(7):2021-4. doi: 10.1128/aem.56.7.2021-2024.1990.
A medium containing a chromogenic substrate was developed for the enumeration of Escherichia coli on the basis of beta-glucuronidase activity. In this medium there was an inverse linear relationship between the log initial E. coli concentration and the time taken for the color to reach a threshold optical density of 0.05. This relationship applied even when the E. coli population contained 5% beta-glucuronidase-negative cells. Incubation at 44 degrees C reduced the time taken for color development and allowed the procedure to be used in the presence of a competitive microflora that outnumbered the E. coli population by a factor of 10(4). Sodium lauryl sulfate as an additional selective agent gave no significant improvement. In the analysis of environmental water samples, the technique gave a good correlation with a standard cultural method. The procedure shows promise as a simple method for testing the compliance of environmental samples with microbiological criteria for E. coli.
基于β-葡萄糖醛酸酶活性开发了一种含有显色底物的培养基，用于大肠杆菌的计数。在这种培养基中，初始大肠杆菌浓度的对数与颜色达到0.05的阈值光密度所需的时间之间存在反线性关系。即使大肠杆菌群体中含有5%的β-葡萄糖醛酸酶阴性细胞，这种关系仍然适用。在44℃下孵育减少了显色所需的时间，并使得该方法能够在竞争性微生物群落数量比大肠杆菌群体多10⁴倍的情况下使用。添加十二烷基硫酸钠作为额外的选择剂并没有显著改善效果。在环境水样分析中，该技术与标准培养方法具有良好的相关性。该方法有望成为一种简单的方法，用于测试环境样品是否符合大肠杆菌的微生物标准。
