The community characteristics and functions of methanotrophs in karst Lake Caohai, Guizhou Plateau

Abstract

草海是由喀斯特盆地积水发育而形成的一个完整的、典型的高原湖泊湿地生态系统，同时也是中国面积最大的岩溶构造湖.甲烷氧化菌作为一类能够将甲烷氧化为CO₂和水的独特微生物，其活动与生态系统中能量流动和元素循环的关键步骤密不可分.为了解贵州草海喀斯特高原湖泊湿地中甲烷氧化菌的群落结构特征及功能，利用宏基因组技术对浅水沼泽、莎草湿地、深水沉积物进行研究.结果表明，草海湿地中主要的好氧甲烷氧化菌为Methylobacter和Methylomonas，主要的厌氧甲烷氧化菌为Candidatus_Methylomirabilis_oxyfera，属于NC10门的反硝化型厌氧甲烷氧化菌.所研究的4种代谢功能基因种类多样性表现为碳代谢＞氮代谢＞硫代谢＞甲烷代谢；基于KEGG数据库共注释到6大类功能和18条与碳、甲烷、氮、硫相关的完整代谢路径.PCoA分析表明浅水沼泽和莎草湿地中甲烷氧化菌的种类和功能相似，且与深水沉积物存在差异.物种与功能相关性网络分析结果显示Methylacidiphilum_fumariolicum和Methylacidiphilum_kamchatkense与草海湖泊湿地中的各个代谢功能均具有较强的相关性.显著影响草海湿地中大多数甲烷氧化菌的群落结构的环境因素是硝酸盐、电导率、总磷和有机质.;Lake Caohai is a complete and typical plateau lake wetland ecosystem formed by the accumulation of water in the karst basin. It is also the largest karst structural lake in China. Methanotrophs is a kind of unique microorganisms that can oxidize methane to CO₂ and water. Their activities are inseparable from the key steps of energy flow and element cycle in the ecosystem. In order to understand the community structure and function of methanotrophs in the wetland of karst Lake Caohai, Guizhou Plateau, we used metagenomics technology to study shallow-water marshes, sedge wetlands, and deep-water sediments. The results showed that the main aerobic methanotrophs in the Lake Caohai wetland were Methylobacter and Methylomonas, and the main anaerobic methanotrophs were Candidatus_Methylomirabilis_oxyfera, which belonged to the NC10 denitrifying anaerobic methanotrophs. The diversity of the four metabolic function genes studied is carbon metabolism>nitrogen metabolism>sulfur metabolism>methane metabolism; based on the KEGG database, a total of 6 categories of functions and 18 complete metabolisms related to carbon, methane, nitrogen, and sulfur are annotated path. PCoA analysis showed that the types and functions of methanotrophs in shallow-water marshes and sedge wetlands are similar and different from those in deep-water sediments. Species and function correlation network analysis results show that Methylacidiphilum_fumariolicum and Methylacidiphilum_kamchatkense have strong correlations with the various metabolic functions in the Lake Caohai wetland. The environmental factors that significantly affect the community structure of methanotrophs in Lake Caohai wetland are nitrate, electrical conductivity, total phosphorous and soil organic matter.