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Bacterial community shifts in decomposing cowpats and the subsequent impacts on fecal source indicators for water quality monitoring
Ecological Indicators ( IF 6.9 ) Pub Date : 2020-03-12 , DOI: 10.1016/j.ecolind.2020.106239
Megan Devane , Beth Robson , Susan Lin , Paula Scholes , David Wood , Louise Weaver , Jenny Webster-Brown , Brent Gilpin

The intensification of dairy farming on the agricultural landscape in New Zealand has raised concerns about pollution sources from dairy fecal runoff into waterways. An important step for mitigation of pollution is the identification of the sources of fecal contamination.

An amplicon-based metagenomic assay of the bacterial community mobilised into runoff from decomposing cowpats revealed shifts in the community composition over five and a half months of on-field decomposition. Mobilised fractions from the cowpats showed major bacterial community shifts from the anaerobic bacteria (Clostridiales and Bacteroidales) that dominate the cow rumen and fresh cowpat, to the bacterial Orders of the Actinomycetales, Sphingobacteriales and Flavobacteriales. These bacterial community shifts were in conjunction with summertime conditions of low rainfall and high sunshine hours coupled with reduced water availability. The impacts of these bacterial shifts is discussed in terms of their effects on the indicators used for water quality monitoring: the fecal indicator bacterium, Escherichia coli, and fecal source tracking (FST) markers (host-associated quantitative polymerase chain reaction (qPCR) markers and fecal steroids). The hypothesis that these bacterial community shifts would impact on the steroid ratios used as FST signatures was disproved. The fecal steroids were, therefore, reliable indicators of fecal sources from cowpats, which had been decomposing for up to five and a half months post-deposition. Consistent with the noted bacterial community changes, there were, however, concentration decreases in the bacterial groups targeted by the faecal source qPCR markers, and the E. coli mobilised from decomposing cowpats.



中文翻译:

细菌群落在分解牛粪方面的变化以及对粪便源指标的影响,以监测水质

新西兰农业景观上奶牛养殖业的集约化引起了人们对从奶牛粪便径流到水道的污染源的担忧。减轻污染的重要步骤是识别粪便污染的来源。

基于细菌的扩增子的宏基因组分析,从分解的小牛拍动到径流中,揭示了在五个半月的现场分解过程中群落组成的变化。来自牛pat的动员部分显示出主要的细菌群落转变,从占牛瘤胃和新鲜牛pat的厌氧菌(梭状芽孢杆菌和拟杆菌)到放线菌,鞘氨醇杆菌和黄杆菌的细菌级。这些细菌群落的变化是与夏季降雨少,日照时间长以及可用水量减少的条件相结合的。讨论了这些细菌迁移对水质监测指标的影响:粪便指标细菌大肠杆菌和粪便来源跟踪(FST)标记(与宿主相关的定量聚合酶链反应(qPCR)标记和粪便类固醇)。这些细菌群落转移会影响用作FST信号的类固醇比率的假说被反驳。因此,粪便类固醇是牛粪中粪便来源的可靠指标,粪便在分解后已经分解了长达五个半月。但是,与注意到的细菌群落变化相一致,粪便源qPCR标记物靶向的细菌组中的浓度降低了,而从分解的牛pat动员了大肠杆菌

更新日期:2020-03-12
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