滇池水中细菌和古菌氮代谢功能基因的空间分布

Spatial Distribution of Nitrogen Metabolism Functional Genes of Eubacteria and Archaebacteria in Dianchi Lake

氮代谢在滇池水生态系统氮素循环和转化过程中起到重要的作用,不仅真核生物参与氮素转化,原核生物作为氮素循环的主要驱动者,在氮素生物化学循环中的作用更不容忽视.基于16S rDNA高通量测序技术,监测滇池草海和外海区域13个点位,分析滇池水中原核生物氮循环功能关键基因的分布特征.结果发现,滇池水中细菌35门,427属,主要以变形菌门和拟杆菌门为优势门类;古菌14门,61属,主要以广古菌门为优势门类;β多样性指数显示滇池整体细菌丰富度指数高于古菌,草海细菌多样性指数高于外海.PICRUSt功能解析表明细菌和古菌具有功能上的丰富性,细菌中有35个参与氮代谢的KO通路,涉及氮异化硝酸盐还原基因nirB、一氧化氮还原酶基因norB和硝酸还原酶基因nasK等关键基因;古菌中有23个参与氮代谢的KO通路,涉及固氮酶基因nifH、nifK和nifD,古菌固氮酶基因拷贝数显著高于其它氮代谢基因,草海中古菌氮代谢能力整体高于外海,滇池水中古菌比细菌固氮潜能更大.本研究从原核生物氮循环中功能基因的角度,探讨滇池不同区域水中细菌和古菌氮循环差异,为进一步揭示氮循环机制,解决氮素污染引起的富营养化提供理论参考.

Nitrogen metabolism plays an important role in the nitrogen cycle and transformation in Dianchi Lake.Not only do eukaryotes participate in nitrogen transformation but prokaryotes,as the main drivers of the nitrogen cycle,also play an extremely important role in the nitrogen cycle.Based on 16 S rDNA high-throughput sequencing technology,13 sites in Caohai and Waihai of Dianchi Lake were monitored,and PICRUSt function analysis method was adopted to analyze the microbial community diversity and key genes of nitrogen metabolism in Dianchi Lake.Bacteria belonging to 35 phyla and 427 genera were found in Dianchi Lake water and mainly included Proteobacteria and Bacteroidetes.Archaea had 14 phyla and 61 genera and mainly belonged to Euryarchaeota.The overall bacterial richness index of Dianchi Lake was higher than that of archaea,and the bacterial diversity index of Caohai was higher than that of Waihai.Functional prediction showed functional richness of bacteria and archaea.There were 35 KO pathways involved in nitrogen metabolism in bacteria,including key genes such as nitrogenous nitrate-reducing gene nirB,nitric oxide reductase gene norB in denitrification,and nitroreductase gene nasK.There were 23 KO pathways involved in nitrogen metabolism in archaea,involving nifH,nifK,and nifD nitrogenase genes in nitrogen fixation.The copy number of nitrogenase genes was significantly higher than that of other nitrogenase genes.The copy number of nitrogen-fixing genes of archaea was higher than that of bacteria,the nitrogen metabolism capacity of archaea in Caohai was higher than that in Waihai,and the potential of nitrogen-fixation of archaea in Dianchi Lake water was higher than that of bacteria.From the perspective of community structure and function prediction of bacteria and archaea,this study discussed the differences of nitrogen cycle in bacteria and archaea in different areas of Dianchi Lake and provided a decision basis for water environment management in Dianchi Lake.