Lai Ellen, Hess Matthias, Mitloehner Frank M
Department of Animal Science, University of California, Davis, Davis, CA, United States.
DOE Joint Genome Institute, Walnut Creek, CA, United States.
Front Microbiol. 2018 Aug 20;9:1964. doi: 10.3389/fmicb.2018.01964. eCollection 2018.
Vermifiltration is a biological treatment process during which earthworms (e.g., ) and microorganisms reduce the organic load of wastewater. To infer microbial pathways responsible for nutrient conversion, past studies characterized the microbiota in vermifilters and suggested that nitrifying and denitrifying bacteria play a significant role during this wastewater treatment process. In contrast to previous studies, which were limited by low-resolution sequencing methods, the work presented here utilized next generation sequencing to survey in greater detail the microbiota of wastewater from a commercial dairy during various stages of vermifiltration. To complement sequence analysis, nitrogenous compounds in and gaseous emissions from the wastewater were measured. Analysis of 16S rRNA gene profiles from untreated wastewater, vermifilter influent, and vermifilter effluent suggested that members of , a family of the involved in denitrification, increased in abundance during the vermifiltration process. Subsequent functional gene analysis indicated an increased abundance of nitrification genes in the effluent and suggested that the nitrogen removal during vermifiltration is due to the microbial conversion of ammonia, a finding that was also supported by the water chemistry and emission data. This study demonstrates that microbial communities are the main drivers behind reducing the nitrogen load of dairy wastewater during vermifiltration, providing a valuable knowledge framework for more sustainable and economical wastewater management strategies for commercial dairies.
蚯蚓过滤是一种生物处理过程，在此过程中蚯蚓（如……）和微生物降低了废水的有机负荷。为了推断负责养分转化的微生物途径，过去的研究对蚯蚓滤池中的微生物群进行了表征，并表明硝化细菌和反硝化细菌在该废水处理过程中发挥了重要作用。与以往受低分辨率测序方法限制的研究不同，本文所开展的工作利用新一代测序技术，更详细地调查了商业奶牛场在蚯蚓过滤各个阶段的废水微生物群。为了补充序列分析，还对废水中的含氮化合物和气态排放物进行了测量。对未经处理的废水、蚯蚓滤池进水和蚯蚓滤池出水的16S rRNA基因图谱分析表明，参与反硝化作用的变形菌门的一个科的成员在蚯蚓过滤过程中丰度增加。随后的功能基因分析表明出水中硝化基因的丰度增加，并表明蚯蚓过滤过程中的氮去除是由于氨的微生物转化，水化学和排放数据也支持了这一发现。这项研究表明，微生物群落是蚯蚓过滤过程中降低奶牛场废水氮负荷的主要驱动因素，为商业奶牛场更可持续和经济的废水管理策略提供了有价值的知识框架。
