Stetler R E, Williams F P
Biohazard Assessment Research Branch, National Exposure Research Laboratory, US Environmental Protection Agency, Cincinnati, OH 45268, USA.
Lett Appl Microbiol. 1996 Jul;23(1):49-54. doi: 10.1111/j.1472-765x.1996.tb00027.x.
Somatic salmonella (SS) phages were commonly found in higher numbers than F-specific RNA (FRNA) coliphages in a multi-site survey of contamination-vulnerable groundwaters. The relative abundance of SS phages required that a pretreatment procedure be implemented to reduce the SS phage content of samples before FRNA coliphage assay with Salmonella typhimurium WG49. Pretreatment involved selective SS phage removal by Salm. typhimurium WG45 cells. This pretreatment proved effective in producing interference-free samples throughout the one-year survey period and in seeded evaluation, was shown not to affect the detection of representative FRNA coliphage MS2. During the survey, 30 groundwater sites located in the continental United States, Puerto Rico and the Virgin Islands were examined for FRNA coliphages and SS phages at monthly intervals. FRNA coliphages were detected at six of the 30 sites and in 33 of 329 monthly samples. SS phages were also detected at six sites and in 28 of 329 monthly samples. Five of the phage-positive sites were positive for both phage groups. At those five sites, 58 monthly samples were collected during the survey period. Those 58 samples yielded an average FRNA coliphage concentration of 140 pfu per 100 l of groundwater as compared to an average SS phage concentration of 565 pfu per 100 l of groundwater. Twenty of the 58 samples were positive for both the FRNA coliphages and SS phages. In those samples, FRNA coliphages were more abundant in five samples; SS phages were more abundant in 15 samples. Because these results demonstrate that SS phage levels may often exceed FRNA coliphage levels in environmental waters, it is clear that SS phage removal procedures will greatly enhance the effectiveness of the WG49-based FRNA coliphage assay.
在一项针对易受污染地下水的多地点调查中，发现体细胞沙门氏菌（SS）噬菌体的数量通常高于F特异性RNA（FRNA）大肠杆菌噬菌体。由于SS噬菌体的相对丰度较高，因此在使用鼠伤寒沙门氏菌WG49进行FRNA大肠杆菌噬菌体检测之前，需要实施预处理程序以降低样品中的SS噬菌体含量。预处理包括通过鼠伤寒沙门氏菌WG45细胞选择性去除SS噬菌体。在为期一年的调查期间，这种预处理被证明能有效产生无干扰的样品，并且在接种评估中，结果表明其不会影响代表性FRNA大肠杆菌噬菌体MS2的检测。在调查期间，每月对位于美国大陆、波多黎各和美属维尔京群岛的30个地下水地点进行FRNA大肠杆菌噬菌体和SS噬菌体检测。在30个地点中的6个以及329个月度样品中的33个检测到了FRNA大肠杆菌噬菌体。在6个地点以及329个月度样品中的28个检测到了SS噬菌体。噬菌体阳性的6个地点中有5个同时检测到了这两种噬菌体。在这5个地点，调查期间共采集了58个月度样品。这58个样品中，FRNA大肠杆菌噬菌体的平均浓度为每100升地下水140个噬菌斑形成单位，而SS噬菌体的平均浓度为每100升地下水565个噬菌斑形成单位。58个样品中有20个同时检测到了FRNA大肠杆菌噬菌体和SS噬菌体。在这些样品中，有5个样品中FRNA大肠杆菌噬菌体更为丰富；有15个样品中SS噬菌体更为丰富。由于这些结果表明环境水体中SS噬菌体水平可能经常超过FRNA大肠杆菌噬菌体水平，显然去除SS噬菌体的程序将大大提高基于WG49的FRNA大肠杆菌噬菌体检测的有效性。
