Identification of bacteria involved in the decomposition of lignocellulosic biomass treated with cow rumen fluid by metagenomic analysis

Chol Gyu Lee, Yasunori Baba, Ryoki Asano, Yasuhiro Fukuda, Chika Tada, Yutaka Nakai

    Research output: Contribution to journalArticlepeer-review

    6 Citations (Scopus)

    Abstract

    We had developed a new pretreatment system using cow rumen fluid to improve the methane production from lignocellulosic substrates. However, the pretreatment conditions differ from the in-situ rumen environment, therefore different microbes may be involved in plant cell wall decomposition. In the current study, shotgun metagenomic analysis using MiSeq platform was performed to elucidate the bacteria which produce cellulase and hemicellulase in this pretreatment system. The rumen fluid which contained waste paper pieces (0.1% w/v) were incubated at 37°C during 120 h. The fluid samples were collected from the reactor at each time-point and analyzed for chemical properties. Rumen microbial DNA was extracted from 0-h and 60-h samples and subjected to shotgun-metagenomic analysis. After pretreatment, approximately half of cellulose and hemicellulose contents of the waste paper were decomposed and some volatile fatty acids were accumulated. Clostridia (e.g., Ruminococcus and Clostridium) were the predominant bacteria before and after 60-h pretreatment, and their relative abundance was increased during pretreatment. However, Prevotella and Fibrobacter, one of the most dominant bacteria in-situ rumen fluid, were observed less than 3% before incubation and they were decreased after pretreatment. Genes encoding cellulase and hemicellulase were mainly found in Ruminococcus, Clostridium, and Caldicellulosiruptor. Calicellulosiruptor, which had not been previously identified as the predominant genus in lignocellulose decomposition in in-situ rumen conditions, might be considered as the main fibrolytic bacterium in this system. Thus, this study demonstrated that the composition of fibrolytic bacteria in this system was greatly different from those in the in-situ rumen.

    Original languageEnglish
    Pages (from-to)137-141
    Number of pages5
    JournalJournal of Bioscience and Bioengineering
    Volume130
    Issue number2
    DOIs
    Publication statusPublished - 2020 Aug

    Keywords

    • Caldicellulosiruptor
    • Clostridium
    • Plant cell wall pretreatment
    • Rumen fluid
    • Ruminococcus
    • β-Glucanase

    ASJC Scopus subject areas

    • Biotechnology
    • Bioengineering
    • Applied Microbiology and Biotechnology

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