AUTHOR=Yang Shu , Li Lei , Peng Xuya , Zhang Rui , Song Liyan 

TITLE=Methanogen Community Dynamics and Methanogenic Function Response to Solid Waste Decomposition

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.743827

DOI=10.3389/fmicb.2021.743827

ISSN=1664-302X

ABSTRACT=Methane production during solid waste decomposition is a typical methanogens-mediated and enzyme-catalyzed anaerobic digestion (AD). Methanogen community dynamics and metabolic diversity during the decomposition is not known. In this study, we investigated methanogen community dynamics and methanogenic pathways during solid waste decomposition in a bioreactor using high throughout Illumina MiSeq sequencing and PICRUSt, respectively. We also related the methanogen community differences with solid waste and leachate physiochemical parameters. Results showed that the percentage of biodegradable matter (BDM) in solid waste decreased from 55 ± 5% in aerobic phase (AP) to 30 ± 2% in anaerobic acid phase (ACP), and to 13 ± 11% in methanogenic phase (MP), resulting in 76% BDM consumption by microbes. Methanogen community structure varied in AP, ACP and MP that Methanomicrobiales and Methanosarcinales was dominant in AP and MP and archaea E2 was abundant in ACP. Each phase had abundant core methanogen orders, genera and species with significant difference (p < 0.05). Redundancy analysis showed that biochemical oxygen demand (BOD5) and nitrate significantly influenced methanogen community composition, suggesting methanogen community structure is nutrient-dependent. Two methanogenic pathways including acetoclastic and hydrogenotrophic pathways with associated functional genes differed at three phases. ACP had the lowest abundance of these genes, indicating that methanogenesis was inhibited in acidogenesis. Abundant hydrogenotrophic and acetoclastic methanogenesis functional genes in MP and AP are in response of the abundant of the Methanomicrobiales and Methanosarcinales. The findings provide previously unidentified insight into the mechanism by which methanogen community structure and function on solid waste bioconversion for methane.