Hodgson C J, Bulmer N, Chadwick D R, Oliver D M, Heathwaite A L, Fish R D, Winter M
North Wyke Research, Okehampton, Devon, UK.
Lett Appl Microbiol. 2009 Jul;49(1):124-30. doi: 10.1111/j.1472-765X.2009.02630.x. Epub 2009 Apr 30.
A laboratory assay for comparative characterization of various faecal matrices with respect to faecal indicator organism (FIO) release using, artificial rain water.
Fresh sheep and beef-cattle faeces, dairy cattle slurry and beef cattle farm yard manure (FYM) were collected from commercial units in south-west England and applied to 20 randomized 1 m(2) plots established on permanent grassland. Representative samples from each faecal matrix (n = 5) were collected on four occasions over 16 days. One gram of each sample was transferred to a sterile vial to which 9 ml of standard local rain was carefully pipetted. The vial was then rotated through 360 degrees, 20 times in 60 s to 'simulate' a standardized interaction of the faecal material with rainfall, providing an assay of comparative release potential. Appropriate decimal dilutions were prepared from the eluent. Following agitation, with a sterile spatula, the remaining faecal material and eluent in the vials were vortex mixed for 60 s before decimal dilutions were prepared from the resulting mixture, providing a quantitative assessment of the total FIO in the sample from which percentage release could be determined. Bacterial concentrations were enumerated in duplicate by membrane filtration following standard methods for FIO. Significant differences in release kinetics of Escherichia coli and enterococci from each of the faecal matrices were determined.
Differences in release from each faecal substrate and between FIO type (E. coli and intestinal enterococci) were observed in this laboratory study. The order of release of E. coli from the faecal matrices (greatest to least, expressed as a percentage of the total present) was dairy cattle slurry > beef cattle FYM > beef-cattle faeces > sheep faeces. For intestinal enterococci the order of percentage release was dairy cattle slurry > beef-cattle faeces > beef cattle FYM > sheep faeces.
This laboratory-based method provides the first data on the relative release kinetics of FIO from different faecal matrices in rain water. This is fundamental information needed to parameterize laboratory-based microbial models and inform approaches to field and catchment risk assessment.
采用人工雨水对各种粪便基质中粪便指示生物（FIO）释放情况进行比较特征分析的实验室检测方法。
从英格兰西南部的商业单位收集新鲜绵羊和肉牛粪便、奶牛粪便以及肉牛场厩肥（FYM），并将其施用于在永久草地上设置的20个随机的1平方米地块。在16天内分四次从每种粪便基质中采集代表性样本（n = 5）。将每份样本1克转移至无菌小瓶中，小心地向其中加入9毫升标准本地雨水。然后将小瓶在60秒内旋转360度20次，以“模拟”粪便物质与降雨的标准化相互作用，从而对比较释放潜力进行检测。从洗脱液中制备适当的十进制稀释液。搅拌后，用无菌刮铲将小瓶中剩余的粪便物质和洗脱液涡旋混合60秒，然后从所得混合物中制备十进制稀释液，从而对样本中的总FIO进行定量评估，由此可确定释放百分比。按照FIO的标准方法通过膜过滤对细菌浓度进行一式两份计数。确定了每种粪便基质中大肠杆菌和肠球菌释放动力学的显著差异。
在本实验室研究中观察到了每种粪便底物以及FIO类型（大肠杆菌和肠道肠球菌）之间释放情况的差异。粪便基质中大肠杆菌的释放顺序（从最大到最小，以总量的百分比表示）为奶牛粪便＞肉牛场厩肥＞肉牛粪便＞绵羊粪便。对于肠道肠球菌，释放百分比顺序为奶牛粪便＞肉牛粪便＞肉牛场厩肥＞绵羊粪便。
这种基于实验室的方法提供了关于雨水中不同粪便基质中FIO相对释放动力学的首批数据。这是参数化基于实验室的微生物模型以及为现场和集水区风险评估方法提供信息所需的基础信息。
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