Metagenomic analysis of a top-down enriched straw biodegradation synthetic bacterial consortium (StrBsyn) facilitates anaerobic rice straw degradation

Abstract

Lignocellulose is a complex and recalcitrant component of plant biomass. Traditional sources of lignocellulose-degrading microorganisms are the rumen system of herbivores and soil microorganisms, with limited studies on marine sediments. In this study, we employed a "top-down" approach to construct a straw biodegradation synthetic bacterial consortium (StrB_syn) capable of degrading lignocellulose from offshore marine sediments. It achieved 66.74 % cellulose, 63.79 % hemicellulose, and 42.85 % lignin conversion within 30 days using 0.2 % rice straws. Additionally, the maximum concentrations of total organic carbon (TOC) and total volatile fatty acids (TVFA) reached 4.66 g/ml and 15.10 g/L, respectively, with a significant increase in pH. β-glucosidase, xylanase, laccase, and lignin peroxidase activities were detected in StrB_syn. Metagenomic sequencing revealed a dynamic shift in the community composition and functional genes. The taxonomic assignment of these functional genes suggested the genera Clostridium, Glomeromyces, and Sedimentobacter as major contributors to carbohydrate transport, metabolism, and lignin degradation processes. This study demonstrated the significant potential of harnessing the power of marine sediment microbial communities for sustainable and efficient anaerobic lignocellulose bioconversion.