基于mcrA基因的沁水盆地煤层气田产甲烷菌群与途径分析

摘要

[Objective] To analyse methanogenic community and the pathway of biogenic methane in the formation water from coalbed methane (CBM) wells in the Qinshui Basin.[Methods] Based on the methyl coenzyme-M reductase (mcrA) gene,the diversity of methanogens from different CBM wells formation water were investigated by 454 pyrosequencing and aligning mcrA sequences from NCBI functional genes library.[Results] The high-throughput sequencing indicated that the numbers of OTUs (Operational taxonomic units) were 64 to 157 in five detected methanogens communities,only 22 OTUs were identical in all samples,which accounted for 14％ to 34％ in each sample.According to the alignment results of high-throughput sequencing data and mcrA library,four genera were detected in five formation water,including Methanobacterium,Methanomicrobium,Methanolobus and Methanospirillum,the dominant genus was Methanobacterium.Phylogenetic analysis indicated that the majority of unidentified genera were closely related to Methanobacterium,Methanomicrobium,Methanococcus and Methanoculleus.Although the percentage of methanogens was different in five sample,the detected genera were about the same.The hydrogenotrophic methanogenesis was main pathway of methane formation in the Qinshui Basin.[Conclusion] The methanogens species were obvious different in different CBM blocks of the Qinshui Basin.However,methanogenesis pathways were similar and had no correlation with the geographical location and reservoir conditions.%[目的]分析沁水盆地煤层气田不同煤层气井产出水样中产甲烷菌群和生物成因气的生成途径.[方法]以甲基辅酶M还原酶基因(mcrA)作为目标基因,采用454焦磷酸高通量测序方法,同时比对NCBI功能基因文库中的mcrA序列,分析不同煤层气井产出水中的产甲烷菌群.[结果]高通量测序表明,5个出水样产甲烷菌群OTUs (Operational taxonomic units)数为64-157个,共有的为22个,各占样品总数14％-34％;样品共检测到4种已知菌属,即甲烷杆菌属(Methanobacterium)、甲烷微菌属(Methanomicrobium)、甲烷叶菌属(Methanolobus)和甲烷螺菌属(Methanospirillum),优势菌属均为Methanobacterium.系统发育分析表明,未明确地位的菌属主要与Methanobacterium、Methanomicrobium、产甲烷球菌属(Methanococcus)和甲烷囊菌属(Methanoculleus)有较近的亲缘关系.5个样品中菌属所占比例不同,检测到的菌属类别大致相同.所有检测样品生物成因煤层气(Coalbed methane,CBM)的生成途径主要为氢营养型产甲烷途径.[结论]沁水盆地不同煤层气田产甲烷菌群菌种差异比较大,但生物成因气生成途径基本相似,与地理位置和煤藏条件没有相关性.