Mutualism between degraders and nondegraders stabilizes the function of a natural biopolymer-degrading community

作者：Liang Liu, Chang Fu Tian, Miaoxiao Wang, Luo Ying, Yaru Huang, Tingting Jiang, Hongwen Zhao, Qijun Yu, En Tao Wang, Jinshui Yang, Hongli Yuan · 发表于：Proceedings of the National Academy of Sciences · 年份：2025 · DOI：10.1073/pnas.2500664122 · 被引用次数：16 · 研究领域：Microplastics and Plastic Pollution、biodegradable polymer synthesis and properties、Diatoms and Algae Research

Natural biopolymer-degrading microbial communities drive carbon biogeochemical cycling. Within these communities, polymer degraders facilitate the growth of nondegraders by breaking down polymers through extracellular enzymes. However, the contributions of nondegraders to community dynamics, as well as the mechanisms that limit their access to degradation products, remain poorly understood. Here, we investigate EMSD5, a lignocellulose-degrading microbial community that efficiently converts corncob into isopropanol. We demonstrate that nondegraders, such as Escherichia coli , enable the growth of degraders (e.g., Lachnoclostridium sp. and Clostridium beijerinckii ) by creating anaerobic conditions and supplying biotin. Within such expanded niches, lignocellulose degradation proceeds sequentially, and the availability of breakdown products to E . coli is constrained by two interlinked processes. Specifically, Lachnoclostridium sp. produces oligosaccharides that are largely inaccessible to E . coli . A subset of these oligosaccharides is utilized by C . beijerinckii to produce monosaccharides that support E . coli growth, while glycosidase secretion by C . beijerinckii is reduced under coculture conditions. Building on these findings, we designed a synthetic consortium by coculturing C. beijerinckii with an engineered E . coli strain that expresses xylanase genes from an unculturable Lachnoclostridium . This consortium achieved isopropanol production from hemicellulose without r...