Identification of bacteria involved in the decomposition of lignocellulosic biomass treated with cow rumen fluid by metagenomic analysis
Identification of bacteria involved in the decomposition of lignocellulosic biomass treated with cow rumen fluid by metagenomic analysis
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DOI：
10.1016/j.jbiosc.2020.03.010
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发表时间：
2020-08-01
影响因子：
2.8
通讯作者：
Nakai, Yutaka
中科院分区：
文献类型：
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作者：
Lee, Chol Gyu;Baba, Yasunori;Nakai, Yutaka
我们利用奶牛瘤胃液开发了一种新的预处理系统，以提高木质纤维基质的甲烷产量。但由于处理条件不同于原位瘤胃环境，因此不同的微生物可能参与了植物细胞壁的分解。在本研究中，利用MiSeq平台进行了鸟枪式超基因组分析，以阐明在该前处理系统中产生纤维素酶和半纤维素酶的细菌。将含有0.1%w/v废纸的瘤胃液在37℃下孵化120h，在每个时间点从反应器中采集液体样本，并进行化学性质分析。从0-h和60-h的样品中提取瘤胃微生物DNA，进行鸟枪式微基因组分析。经过预处理后，废纸中的纤维素和半纤维素含量约有一半被分解，并积累了一些挥发性脂肪酸。60h前和60h后优势菌为梭状芽孢杆菌(如瘤胃球菌和梭状芽孢杆菌)，其相对丰度在预处理过程中有所增加。而瘤胃液中最具优势的细菌之一普氏杆菌和纤维杆菌在培养前不到3%，处理后有所下降。纤维素酶和半纤维素酶编码基因主要存在于瘤胃球菌、梭状芽孢杆菌和Caldicellulosiruptor中。Calicellulosiruptor是在瘤胃条件下分解木质纤维素的优势菌，但可能是该体系中的主要纤维分解菌。因此，本研究表明，该系统中纤维分解菌的组成与原位瘤胃中的有很大不同。(C)2020年，日本生物技术学会。版权所有。
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 platformwas 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 degrees 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. (C) 2020, The Society for Biotechnology, Japan. All rights reserved.