厌氧氨氧化细菌富集培养过程微生物结构与功能解析

Evolution of microbial structures and functions during the enrichment of Anammox bacteria

为了研究厌氧氨氧化细菌富集培养过程中微生物结构与功能的关系,本研究采集升流式污泥床反应器(Upflow anaerobic sludge bed,UASB)中厌氧氨氧化反应启动与驯化过程的样品,结合传统微生物培养方法和分子生物学手段,对启动过程中的氮素转化功能基因、异养菌演替及菌群演替进行了定性与定量分析.结果表明,随着总氮去除率从1.39%升高至79.62%,厌氧氨氧化细菌功能基因hzo大量富集,且统计分析结果表明nirS是影响脱氮效果的关键因素.微生物菌群在门水平上主要优势菌门为厌氧氨氧化细菌所在的浮霉菌门(Planctomycetes),在属水平上的优势菌属为Candidatus Kuenenia,丰度从4.75%升高至48.77%.这些都表明厌氧氨氧化细菌的成功富集是实现脱氮效果的主要因素.尽管进水无外加碳源,但异养菌始终占有一定的比例,与厌氧氨氧化细菌存在共生现象,却在功能上发生演替.网络分析和基于KEGG数据库的功能预测结果表明,厌氧氨氧化细菌Candidatus Kuenenia和异养菌Ignavibacterium、Gp4呈显著正相关(p<0.05),这些异养菌通过降解或合成胞外物质,分泌次级代谢物质与厌氧氨氧化细菌相互作用,进而影响厌氧氨氧化细菌的活性与生长.

To study the relationship between microbial structure and function during the enrichment of annammox bacteria,sampling was carried out in an upflow anaerobic sludge bed(UASB)reactor during its start⁃up of anammox process,and the combined traditional microbial culture methods and molecular biological methods were used to conduct qualitative and quantitative analysis of functional genes of nitrogen transformation,evolution of heterotrophic bacteria and microbial community.Results showed that the anammox functional gene hzo was successfully enriched with the total nitrogen removal rate increased from 1.39%to 79.62%,and nirS was the key factor affecting the nitrogen removal.The dominant phylum of microbial community was Planctomycetes and the dominant genus was Candidatus Kuenenia.All these indicated that the successful enrichment of anammox was the main factor to achieve high nitrogen removal performance.Heterotrophic bacteria were symbiotic bacteria with anammox bacteria,and evolved in function,because they always occupy in a certain proportion even no organic carbon source was added in the influent.It is indicated that there is significant positive correlation between Candidatus Kuenenia and some heterotrophic bacteria such as Ignavibacterium and Gp4 based on microbial network analysis and function prediction based on KEGG database.These heterotrophic bacteria may interact with anammox by degrading or synthesizing extracellular substances and secreting secondary metabolites,which then affect the activity and growth of anammox bacteria.