title: Metagenome approaches revealed a biological prospect for improvement on mesophilic cellulose degradation.
abstract: Improvement on the bioconversion of cellulosic biomass depends much on the expanded knowledge on the underlying microbial structure and the relevant genetic information. In this study, metagenomic analysis was applied to characterize an enriched mesophilic cellulose-converting consortium, to explore its cellulose-hydrolyzing genes, and to discern genes involved in methanogenesis. Cellulose conversion efficiency of the mesophilic consortium enriched in this study was around 70 %. Apart from methane, acetate was the major fermentation product in the liquid phase, while propionate and butyrate were also detected at relatively high concentrations. With the intention to uncover the biological factors that might shape the varying cellulose conversion efficiency at different temperatures, results of this mesophilic consortium were then compared with that of a previously reported thermophilic cellulose-converting consortium. It was found that the mesophilic consortium harbored a larger pool of putative carbohydrate-active genes, with 813 of them in 54 GH modules and 607 genes in 13 CBM modules. Methanobacteriaceae and Methanosaetaceae were the two methanogen families identified, with a preponderance of the hydrogenotrophic Methanobacteriaceae. In contrast to its relatively high diversity and high abundance of carbohydrate-active genes, the abundance of genes involved in the methane metabolism was comparatively lower in the mesophilic consortium. A biological enhancement on the methanogenic process might serve as an effective option for the improvement of the cellulose bioconversion at mesophilic temperature.
authors.affiliation: Environmental Biotechnology Lab, The University of Hong Kong SAR, Pokfulam Road, Hong Kong, China.
authors.forename: Yubo
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Environmental Biotechnology Lab, The University of Hong Kong SAR, Pokfulam Road, Hong Kong, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xia
authors.affiliation: Environmental Biotechnology Lab, The University of Hong Kong SAR, Pokfulam Road, Hong Kong, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Ju
authors.affiliation: Environmental Biotechnology Lab, The University of Hong Kong SAR, Pokfulam Road, Hong Kong, China. zhangt@hkucc.hku.hk.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
mesh_terms: D000085:Acetates / Q000378:metabolism; D001711:Biotransformation; D002087:Butyrates / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D053858:Metabolic Networks and Pathways / Q000235:genetics; D054892:Metagenome; D008697:Methane / Q000378:metabolism; D017013:Methanobacteriaceae / Q000235:genetics / Q000302:isolation & purification; D019640:Methanosarcinales / Q000235:genetics / Q000302:isolation & purification; D059013:Microbial Consortia; D011422:Propionates / Q000378:metabolism; D013696:Temperature
chemical_list: D000085:Acetates; D002087:Butyrates; D011422:Propionates; D002482:Cellulose; D008697:Methane
keywords: Cellulose degradation; Mesophilic; Metagenomics; Methanogenesis