The Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences,Shijiazhuang, China
【研究目的】了解深部环境中产甲烷菌群落多样性是探索早期生命起源、极端环境生命和调控甲烷产量的基础。然而，地热区深部碳酸盐岩岩溶-裂隙热水中产甲烷菌群落多样性仍然不清。【研究方法】利用地热科学钻探孔抽水试验，采集深部热水样用于产甲烷菌标记基因mcrA高通量测序，分析冀中地热区深部碳酸盐岩岩溶-裂隙热水中的产甲烷菌群落多样性。【研究结果】结果显示，从冀中地热区深部热水中共检出3个纲、4个目、8个属的产甲烷菌，其中隶属于广古菌门、甲烷杆菌纲和甲烷杆菌目的甲烷热杆菌属Methanothermobacter是产甲烷菌的主要类型，占比99.85%；优势菌种是Methanothermobacter wolfeii (相似性达99%，占比71%)，产甲烷菌的主要代谢途径是CO2还原；不同样品产甲烷菌群落多样性不尽相同，但均以甲烷热杆菌属Methanothermobacter为优势菌属，占比均大于99.77%。【结论】本文研究揭示了冀中地热区深部碳酸盐岩岩溶-裂隙热水中含有种类较丰富而组成极不均匀的产甲烷菌群落，拓展了甲烷热杆菌属Methanothermobacter的生境类型，为进一步研究产甲烷菌在地球生态系统的功能奠定了科学基础。
[Objective] Understanding the diversity of methanogenic communities in the deep environment is the basis for exploring the origin of early life, extreme environmental life and regulating methane production. However, the diversity of methanogenic communities in the deep carbonate karst-fracture geothermal water is still unclear. [Methods] The deep geothermal water samples were collected for methanogenic marker gene mcrA-based high-throughput sequencing by the pumping tests performed in the geothermal scientific drilling holes located in the Jizhong geothermal area, China to explore the diversity of methanogenic communities in the deep carbonate rock karst-fracture geothermal water. [Results] Results showed that 3 classes, 4 orders and 8 genera of methanogenic communities were detected in the deep geothermal water, of which Methanothermobacter, belonging to Euryarchaeota, Methanobacteria and Methanobacteriales, was dominant methanogens, accounting for 99.85% of the total sequences. The dominant species based on mcrA was closely affiliated with Methanothermobacter wolfeii (similarity 99%, accounting for 71%). The metabolic pathway of methanogens was mainly the pathway of CO2 reduction. The compositions of methanogenic communities in different samples were different, but Methanothermobacter was a dominant genus in all of the samples, accounting for more than 99.77%. [Conclusions] This study reveals that the deep geothermal water from the carbonate rock karst-fracture geothermal reservoirs contains relatively abundant but extremely uneven compositions of methanogenic communities and expands the habitat type of Methanothermobacter, which provides scientific basis for further studying the function of methanogens in the earth ecosystem.