全国城市污水处理厂中微生物群落的溯源分析

Potential Source Environments for Microbial Communities in Wastewater Treatment Plants (WWTPs) in China

为深入理解城市污水处理厂(wastewater treatment plants,WWTPs)中微生物群落的组成特征,本研究采用16S rRNA基因测序技术,系统地分析了全国15个城市WWTPs中活性污泥(activated sludge,AS)微生物群落的组成和可能的微生物来源.结果表明,15个城市AS群落中相对丰度超过0. 1%的微生物(门水平)共有10种,包括Proteobacteria、Bacteroidetes和Chloroflexi等,优势门的相对丰度之和占AS群落总丰度的94. 53%~97. 04%. AS群落组成在一定程度上受地理因素影响:超过3 000个OTUs只广泛存在于某一个城市的WWTPs中,且接近中国大陆两端的哈尔滨和三亚拥有更多的独特OTUs;同为沿海城市的三亚和大连,其WWTPs中的特征微生物组成最为相似,而成都和重庆WWTPs中未检测到特征微生物.溯源分析的结果表明,AS群落结构能在一定程度上反映WWTPs的进水性质及所在城市的地理环境特征.具体地,植物及土壤来源微生物在不同城市AS群落中均占有较高比例;淡水来源微生物在淡水资源相对较多的南方区域AS群落中所占比例较高;除三亚外,每个城市AS群落中都检测到一定量的工业废水来源微生物,这与城市WWTPs处理部分工业废水有关;而人体肠道微生物在各城市AS群落中的占比均较低.

To better understanding the microbial composition of activated sludge ( AS),unique OTUs and their indicators were examined and SourceTracker was used to identify possible source environments for AS communities to thrive in 15 cities across China, based on 16S rRNA gene sequencing. This may help reveal the underlying mechanisms of AS community composition formations in various areas. The results indicated that the dominant phyla in AS in each city were similar;Proteobacteria,Bacteroidetes,and Chloroflexi made up 94. 53%-97. 04% of the whole microbial communities. Geographic location and environmental conditions were identified as having an effect on microbial compositions. Cities located toward to the edge of China or along the coast tended to harbor more unique OTUs. Moreover,the composition of indicators in wastewater treatment plants (WWTPs) near the sea were more similar, while no indicators were detected in WWTPs in Chengdu and Chongqing. Source environments for AS microbial communities also depended on location and environmental conditions. Overall,microbes from ‘plant’and ‘soil’sources accounted for a large proportion of the AS microbial communities in each city,while bacteria from ‘marine’sources were only detected in coastal AS communities. Cities with more rivers and lakes tended to have more bacteria originating from‘fresh water’sources. Since most of the WWTPs in China play a role in treating industrial wastewater,industrial wastewater was also an important source environment. However,few bacteria originating from the human digestive system were identified in the AS communities. Moreover,a large proportion of bacteria ( 36%-70%) originated from unknown sources not included in the source database,such as sewage infrastructure, indicating that the source database will need to be expanded in the future.