McFeters G A, Cameron S C, LeChevallier M W
Appl Environ Microbiol. 1982 Jan;43(1):97-103. doi: 10.1128/aem.43.1.97-103.1982.
Pure cultures of Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, and Citrobacter freundii were injured ( greater than 90%) in water from a dead-end section of the Bozeman, Montana, distribution system. The effects of the following laboratory variables on the enumeration efficiency of injured and undamaged control cells were examined: (i) diluent composition, temperature, and time of exposure; (ii) media, using various formulations employed in enumerating gram-negative bacteria; and (iii) surface pore morphology of membrane filters. The addition of peptone or milk solids to diluents and low temperature (4 degrees C) maximized the recovery of injured cells, but had little effect on undamaged cells. Control cells were recovered with high efficiencies on most media tested, but recoveries of injured cells ranged from 0 to near 100%. Most of the media commonly used in water analysis recovered less than 30% of injured cells. This was explained in part by the sensitivity of injured bacteria to deoxycholate concentrations greater than 0.01%, whereas control cells were unaffected by 0.1%. Membrane filter surface pore morphology (at 35 degrees C) had a negligible effect on total coliform recoveries. Recommendations are made regarding procedures to improve the recovery of injured coliforms by routine laboratory practices.
在蒙大拿州博兹曼市配水系统死端部分的水中，大肠杆菌、肺炎克雷伯菌、产气肠杆菌和弗氏柠檬酸杆菌的纯培养物受到损伤（损伤率大于90%）。研究了以下实验室变量对受损细胞和未受损对照细胞计数效率的影响：（i）稀释剂组成、温度和暴露时间；（ii）培养基，采用了多种用于革兰氏阴性菌计数的配方；（iii）膜过滤器的表面孔隙形态。在稀释剂中添加蛋白胨或乳固体以及低温（4℃）可使受损细胞的回收率最大化，但对未受损细胞影响不大。在大多数测试培养基上，对照细胞的回收率很高，但受损细胞的回收率在0至近100%之间。水分析中常用的大多数培养基回收的受损细胞不到30%。部分原因是受损细菌对浓度大于0.01%的脱氧胆酸盐敏感，而对照细胞不受0.1%的影响。膜过滤器表面孔隙形态（在35℃下）对总大肠菌群回收率的影响可忽略不计。针对通过常规实验室操作提高受损大肠菌群回收率的程序提出了建议。
