Jones Tineke H, Johns Michael W
Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C & E Trail, Lacombe, Alberta, Canada.
Appl Environ Microbiol. 2009 Oct;75(19):6142-6. doi: 10.1128/AEM.00436-09. Epub 2009 Jul 31.
Male-specific RNA coliphages (F-RNA coliphages) have been proposed as a potential viral indicator of fecal contamination in water and foods because they are easy to culture and are a normal component of the mammalian gut flora. F-RNA coliphage plaque numbers are typically obtained by directly plating a 10-fold dilution of 1 g of fecal material, but the numbers of F-RNA coliphages shed by animals and humans may be too low for direct enumeration. Therefore, the sensitivity of detecting F-RNA coliphages in fecal material was improved by extracting and precipitating F-RNA coliphage from a 10-g fecal sample by use of polyethylene glycol (PEG). The highest recovery of F-RNA coliphage with 10% beef extract, pH 7.2, was obtained in the presence of 1 M NaCl and 10% PEG after 16 h of precipitation, but a pellet was not obtained after a short precipitation time of 2 h. There was no significant difference between eluant-to-fecal-material ratios of 4:1 and 9:1 or homogenization with a stomacher or pulsifier. F-RNA coliphage were detected in 64% (16 of 25 samples) of fecal samples from various sources when the sample size was 10 g but in 36% (9 of 25 samples) of samples when the sample size was 1 g. When F-RNA coliphage were detected in 1-g samples, they were also detected in 10-g samples. When F-RNA coliphage were detected in 10-g samples but not in 1-g samples, the levels were <100 PFU/g.
雄性特异性RNA噬菌体（F-RNA噬菌体）已被提议作为水和食品中粪便污染的潜在病毒指标，因为它们易于培养，且是哺乳动物肠道菌群的正常组成部分。F-RNA噬菌体噬菌斑数量通常通过直接接种1克粪便材料的10倍稀释液来获得，但动物和人类排出的F-RNA噬菌体数量可能过低，无法直接计数。因此，通过使用聚乙二醇（PEG）从10克粪便样本中提取和沉淀F-RNA噬菌体，提高了粪便材料中F-RNA噬菌体的检测灵敏度。在1 M NaCl和10% PEG存在的情况下，沉淀16小时后，使用pH 7.2的10%牛肉提取物可获得F-RNA噬菌体的最高回收率，但短时间沉淀2小时后未获得沉淀颗粒。洗脱液与粪便材料的比例为4:1和9:1，或使用均质器或脉动器进行均质处理，两者之间没有显著差异。当样本量为10克时，64%（25个样本中的16个）来自各种来源的粪便样本中检测到F-RNA噬菌体，但当样本量为1克时，36%（25个样本中的9个）的样本中检测到F-RNA噬菌体。当在1克样本中检测到F-RNA噬菌体时，在10克样本中也能检测到。当在10克样本中检测到F-RNA噬菌体而在1克样本中未检测到时，其水平<100 PFU/g。
