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.

我们已经开发了一种使用牛瘤胃液的新型预处理系统，以改善木质纤维素底物的甲烷产量。但是，预处理条件与原位不同瘤胃环境，因此不同的微生物可能参与植物细胞壁的分解。在当前研究中，使用MiSeq平台进行了shot弹枪宏基因组分析，以阐明在此预处理系统中产生纤维素酶和半纤维素酶的细菌。将含有废纸碎片（0.1％w / v）的瘤胃液在37°C下孵育120小时。在每个时间点从反应器收集流体样品并分析化学性质。从0-h和60-h样品中提取瘤胃微生物DNA，并进行shot弹枪-基因组分析。预处理后，废纸中约一半的纤维素和半纤维素被分解，并且积累了一些挥发性脂肪酸。梭状芽胞杆菌（例如，Ruminococcus和梭状芽胞杆菌（Clostridium）是预处理60小时之前和之后的主要细菌，在预处理过程中它们的相对丰度增加了。然而，普氏菌和Fibrobacter，最主要的细菌之一原位瘤胃流体中，观察到小于3％孵育前，他们预处理后明显降低。编码纤维素酶和半纤维素的基因主要见于瘤胃球菌属，梭状芽孢杆菌和Caldicellulosiruptor。Calicellulosiruptor，以前没有被确定为木质纤维素原位分解的主要属瘤胃条件，可能被认为是该系统中的主要溶纤细菌。因此，该研究表明，该系统中的溶纤细菌的组成与原位瘤胃中的溶纤细菌的组成有很大不同。