Metagenomic And Metaproteomic Analysis For Microbial Degradation Mechanism Of Lignocellulose

Natural lignocellulose is mainly comprised of cellulose, hemicellulose and lignin. Due to its complex structure and stable property, the biodegradation cycle of lignocellulose is time consuming and low efficiency. To investigate the degradation of lignocellulose under natural conditions, untreated sugar bagasse were cultured under spontaneous condition or enriched with the microorganisms from native forest soil respectively gathered from Henan, Jiangxi, Fujian and Yunnan, which represented different climates and vegetation types. For each treatment, the samples were collected in different periods of lignocellulose-degrading process, and the cellulase and xylanase activities for each sample were measured to monitored the change of enzyme activity during the degradation process of bagasse.During the spontaneous degradation process of sugar bagasse, the activities of cellulase and xylanase increased rapidly and subsequently remained at a higher level from the day 42 to day 100. The 45-day-cultured sample was for the following metagenomics and metaproteomics to explore the microorganisms and enzymes involved in the degradation of lignocellulose. In the enriched experiments, the sugar bagasse was degraded more rapidly than that in the spontaneous condition, the enzyme activity of cellulase and xylanase increased rapidly and reached to the highest during the day 20-50. Among them, the sample XG showed a higher activity than the other four soil samples.In the following research, microbial lignocellulose unitization strategy was intensively studied by using the metagenomic and metaproteomic methods. The total genomic DNA was extracted from the 45-day-cultured samples and sequenced using Illumina sequencing. After assembly and annotation, about 755 glycoside hydrolase family genes that involved in carbohydrate metabolism were predicted, including cellulases, xylanases, and amylases etc. In the subsequent metaproteomic analysis,26011 peptides were identified through iTRAQ technique. After simple assembly and the impurity proteins were removed, finally 2004 peptides including 124 enzymes involved in lignocellulose degradation were obtained, most of these enzymes were from ascomycota-based fungi.In the study, the composition and structure of microorganisms and their cellulase involved in the bagasse degradation were explained. With further research, both composition and structure of microorganism and compound enzyme system will be revealed, and the degradation process will also be elucidated eventually.