贵州阿哈湖水库沉积物中甲烷氧化菌分布与功能

Distribution and functions of methanotrophs in the sediments of Aha Lake Reservoir,Guizhou Province

摘要:

甲烷氧化菌是一类能够以甲烷作为唯一碳源和能量维持生存的微生物,其活动与生态系统中物质循环及能量流动密切相关。【目的】了解阿哈湖水库沉积物中甲烷氧化菌群落结构及代谢功能。【方法】采用宏基因组技术对环湖沉积物和湖心沉积物进行研究。【结果】水库沉积物中主要的好氧甲烷氧化菌是甲基杆菌属(Methylobacter) (0.37%)和甲基单胞菌属(Methylomonas) (0.12%),主要的厌氧甲烷氧化菌是Candidatus_Methylomirabilis (0.12%),属于NC10门细菌中的亚硝酸盐反硝化型厌氧甲烷氧化菌,其中好氧甲烷氧化菌的pmoA基因为6.16×10⁷ copies/g,反硝化型厌氧甲烷氧化菌的16S rRNA基因为2.84×10⁷ copies/g。4种代谢的功能基因多样性表现为氮代谢>碳代谢>硫代谢>甲烷代谢,基于京都基因和基因组百科全书(Kyoto encyclopedia of genes and genomes, KEGG)基因库进行注释得到6大类功能,发现18条与碳(包括甲烷)、氮、硫代谢有关的完整代谢途径。主坐标分析(principal coordinates analysis, PCoA)显示环湖沉积物与湖心沉积物之间的甲烷氧化菌种类和功能存在显著差异。影响甲烷氧化菌分布的主要环境因子为氧化还原电位、电导率和硫酸根。【结论】阿哈湖水库甲烷氧化菌以Ⅰ型好氧甲烷氧化菌为主,甲烷氧化菌群落代谢途径丰富,Ⅰ型和Ⅱ型甲烷氧化菌在对O₂的适应性上有显著差异。相关研究可为湖泊水生态环境的保护和微生物资源的开发利用等方面提供一定的理论支撑。

关键词:甲烷氧化菌;阿哈湖;群落结构;功能基因;代谢途径

Abstract:

Methanotrophs can utilize methane as the only carbon source and energy, and they can survive and participate in material circulation and energy flow in ecosystems. 【Objective】 To unveil the structure and functions of methanotrophs community in the sediments from the Aha Lake Reservoir (referred to as the Reservoir), a typical karst lake reservoir in Guiyang City, Guizhou Province. 【Methods】 We used metagenomics to analyze the sediments collected from the edge and the center of the Reservoir. 【Results】 The dominant aerobic methanotrophs were Methylobacter (0.37%) and Methylomonas (0.12%), and the dominant anaerobic methanotrophs were Candidatus_Methylomirabilis (0.12%), being NC10 denitrifying anaerobic methanotrophs. The gene pmoA encoding particulate methane monooxygenase of aerobic methanotrophs had the relative abundance of 6.16×10⁷ copies/g and the 16S rRNA gene had the relative abundance of 2.84×10⁷ copies/g in denitrifying anaerobic methanotrophs. The diversity of four metabolic functional genes followed a trend of nitrogen metabolism>carbon metabolism>sulfur metabolism>methane metabolism. Kyoto encyclopedia of genes and genomes (KEGG) annotation revealed six functions and 18 complete pathways involving carbon (including methane), nitrogen, and sulfur metabolism. The results of principal coordinate analysis (PCoA) showed huge discrepancies in the distribution and functions of methanotrophs between sediments from the edge and the center of the Reservoir. Moreover, redox potential, conductivity, and sulfate were primary environmental factors affecting methanotroph distribution. 【Conclusion】 Type I aerobic methanotrophs dominated the Reservoir with abundant metabolic pathways. Types I and II methanotrophs exhibited huge discrepancies in terms of their adaptability to O₂. All these fundings are expected to provide theoretical support for lake water environment conservation and microbial utilizationation.

Key words:methanotrophs;Aha Lake;community structure;functional gene;metabolic pathway