长期培养和宏组学分析揭示了烃污染环境中的甲基营养型产甲烷途径

Long-Term Cultivation and Meta-Omics Reveal Methylotrophic Methanogenesis in Hydrocarbon-Impacted Habitats

针对石油烃污染的厌氧环境,利用微生物的代谢作用将石油烃转化为甲烷是一种潜在的生物修复策略。然而,目前对于微生物厌氧烃降解产甲烷的机制尚不清楚。经过十年的持续富集和转接培养,我们获得了一种能够降解正构烷烃(C_(15)~C_(20))并且产甲烷富集培养体系,并且经过转接培养该培养物在甲烷生产的动力学特性方面得到了持续的提高。综合宏基因组和宏转录组的分析结果,发现正构烷烃主要通过Desulfosarcinaceae、Firmicutes和Synergistetes菌通过富马酸加成的方式进行起始活化,然后在Tepidiphilus菌的协同作用下进一步降解。同时,体系中含量较多的Anaerolineaceae菌主要负责死细胞生物质的回收。根据宏转录组学分析结果,甲烷主要通过H2依赖型的甲基营养甲烷途径产生,主要由候选门Verstraetearchaeta内的Methanomethyliaceae通过利用死细胞生物质回收代谢过程中产生的三甲胺来产生甲烷。这些发现表明,依赖H2的甲基营养产甲烷菌以及甲基营养产甲烷菌可能在含石油烃的地下生态系统的碳循环过程中发挥着重要的作用。

The microbial conversion of alkanes to methane in hydrocarbon-contaminated environments is an intrinsic bioremediation strategy under anoxic conditions.However,the mechanism of microbial methanogenic alkane degradation is currently unclear.Under ten years of continuous efforts,we obtained a methanogenic n-alkane-degrading(C_(15)–C_(20))enrichment culture that exhibited sustained improvements in the kinetic properties of methane production.The integrated metagenomic and metatranscriptomic analyses revealed that n-alkanes were mainly attacked by members of Desulfosarcinaceae,Firmicutes,and Synergistetes using the fumarate addition strategy,and were then further degraded in a common effort by Tepidiphilus members.Meanwhile,the abundant members of Anaerolineaceae were mainly responsible for cell debris recycling.However,according to the metatranscriptomic analyses,methane was predicted to be produced mainly via H2-dependent methylotrophic methanogenesis,primarily from necromass-derived trimethylamine mediated by Methanomethyliaceae within the candidate phylum Verstraetearchaeota.These findings reveal that H2-dependent methylotrophic methanogens,as well as methylotrophic methanogens,may play important ecological roles in the carbon cycle of hydrocarbon enriched subsurface ecosystems.