Singh Ashish Kumar, Nakhate Suraj Prabhakarrao, Gupta Rakesh Kumar, Chavan Atul Rajkumar, Poddar Bhagyashri Jagdishprasad, Prakash Om, Shouche Yogesh S, Purohit Hemant J, Khardenavis Anshuman Arun
Environmental Biotechnology and Genomics Division, CSIR-National Environmental Engineering Research Institute, Nehru Marg, Nagpur, 440020, Maharashtra, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
National Centre for Microbial Resource, National Centre for Cell Sciences, Pune, Maharashtra, 411007, India.
Environ Res. 2022 Dec;215(Pt 1):114199. doi: 10.1016/j.envres.2022.114199. Epub 2022 Sep 1.
In the present study, the microbial community residing at different depths of the landfill was characterized to assess their roles in serving as a methane sink. Physico-chemical characterization revealed the characteristic signatures of anaerobic degradation of organic matter in the bottom soil (50-60 cm) and, active process of aerobic denitrification in the top soil (0-10 cm). This was also reflected from the higher abundance of bacterial domain in the top soil metagenome represented by dominant phyla Proteobacteria and Actinobacteria which are prime decomposers of organic matter in landfill soils. The multiple fold higher relative abundances of the two most abundant genera; Streptomyces and Intrasporangium in the top soil depicted greater denitrifying taxa in top soil than the bottom soil. Amongst the aerobic methanotrophs, the genera Methylomonas, Methylococcus, Methylocella, and Methylacidiphilum were abundantly found in the top soil metagenome that were essential for oxidizing methane generated in the landfill. On the other hand, the dominance of archaeal domain represented by Methanosarcina and Methanoculleus in the bottom soil highlighted the complete anaerobic digestion of organic components via acetoclasty, carboxydotrophy, hydrogenotrophy, methylotrophy. Functional characterization revealed a higher abundance of methane monooxygenase gene in the top soil and methyl coenzyme M reductase gene in the bottom soil that correlated with the higher relative abundance of aerobic methanotrophs in the top soil while methane generation being the active process in the highly anaerobic bottom soil in the landfill. The activity dependent abundance of endogenous microbial communities in the different zones of the landfill was further validated by microcosm studies in serum bottles which established the ability of the methanotrophic community for methane metabolism in the top soil and their potential to serve as sink for methane. The study provides a better understanding about the methanotrophs in correlation with their endogenous environment, so that these bacteria can be used in resolving the environmental issues related to methane and nitrogen management at landfill site.
在本研究中，对垃圾填埋场不同深度处的微生物群落进行了表征，以评估它们作为甲烷汇的作用。物理化学表征揭示了底部土壤（50 - 60厘米）中有机物厌氧降解的特征信号，以及顶部土壤（0 - 10厘米）中有氧反硝化的活跃过程。这也反映在顶部土壤宏基因组中细菌域的丰度较高，其主要门类为变形菌门和放线菌门，它们是垃圾填埋场土壤中有机物的主要分解者。顶部土壤中两个最丰富的属；链霉菌属和孢囊放线菌属的相对丰度高出数倍，表明顶部土壤中的反硝化类群比底部土壤更多。在好氧甲烷氧化菌中，甲基单胞菌属、甲基球菌属、甲基细胞菌属和嗜酸甲基杆菌属在顶部土壤宏基因组中大量存在，这些对于氧化垃圾填埋场中产生的甲烷至关重要。另一方面，底部土壤中以甲烷八叠球菌属和甲烷袋状菌属为代表的古菌域占主导地位，突出了通过乙酸裂解、一氧化碳营养、氢营养、甲基营养对有机成分进行完全厌氧消化。功能表征显示，顶部土壤中甲烷单加氧酶基因的丰度较高，底部土壤中甲基辅酶M还原酶基因的丰度较高，这与顶部土壤中好氧甲烷氧化菌的相对丰度较高相关，而甲烷生成是垃圾填埋场高度厌氧底部土壤中的活跃过程。通过血清瓶中的微观研究进一步验证了垃圾填埋场不同区域内活性依赖的内源微生物群落丰度，该研究确定了甲烷营养群落对顶部土壤中甲烷代谢的能力及其作为甲烷汇的潜力。该研究更好地理解了甲烷氧化菌与其内源环境的相关性，以便这些细菌可用于解决与垃圾填埋场甲烷和氮管理相关的环境问题。
