【摘要】 为系统探讨海子水牛瘤胃内的微生物组成及木质纤维素降解酶系,本试验利用基于高通量测序的宏基因组学技术对海子水牛(2.5岁左右,平均体重为493 kg)瘤胃液样本进行组学分析。结果表明,共获得了77 283 638条reads,并拼接出744 712个scaffold。经prodigal分析后,共预测出827 044个基因。通过基因注释发现海子水牛瘤胃中含有多种木质纤维素降解微生物,如生黄瘤胃球菌(Ruminococcus flavefaciens)、白色瘤胃球菌(Ruminococcus albus)、产琥珀酸丝状杆菌(Fibrobacter succinogenes)及栖瘤胃普雷沃氏菌(Prevotella ruminicola)。此外,还发现有38 011个基因编码蛋白质具有木质纤维素降解酶活性,其中糖苷水解酶(GH)基因数量最多(17 877个),糖基转移酶(GT)(8 637个)、碳水化合物结合模块(CBM)(4 693个)和碳水化合物酯酶(CE)基因(4 214个)数量次之,多糖裂合酶(PL)(1 296个)和辅助氧化还原酶(AA)基因(934个)数量较少。在GH基因中,归属于GH2、GH43、GH97、GH3家族的基因较多,且编码蛋白质具有寡糖降解酶活性的基因数量最多。此外还发现了少量的纤维小体组分蛋白基因。结合其他物种肠胃宏基因组中GH基因比对分析,发现海子水牛瘤胃中的纤维素酶、半纤维素酶和分支降解酶比例与奶牛瘤胃较为接近。由此可见,海子水牛瘤胃内含有丰富的木质纤维素降解微生物及酶系,这将为筛选具有工业应用潜力的酶基因奠定理论基础。更多还原

【Abstract】 In order to investigate microorganism composition and lignocellulolytic enzymes in rumen of Haizi buffalo,rumen fluid sample of Haizi buffalo( about 2.5 years of age,average body w eight w as 493 kg) w as surveyed using metagenomic high-throughput sequencing. The results show ed as follw s: a total of 77 283 638 reads w ere obtained,w hich w ere assembled into 744 712 scaffolds. And then,a total of 827 044 genes w ere predicted by prodigal analysis. Many microorganisms involved in lignocellulose degradation w ere identified by gene annotation,such as Ruminococcus flavefaciens,Ruminococcus albus,Fibrobacter succinogenes and Prevotella ruminicola. We identified potential 38 011 genes encoding lignocellulolytic enzymes including glycoside hydrolase( G H)( 17 877 genes),glycosyl transferase( G T)( 8 637 genes),carbohydrate binding module( CBM)( 4 693 genes),carbohydrate esterase( CE)( 4 214 genes),polysaccharide lyase( PE)( 1 296 genes),and auxiliary activity( AA)( 934 genes). Among G H genes,most genes belonged to G H2,G H43,G H97 and G H3 families,and a higher abundance of oligosaccharide degrading enzymes in buffalo rumen metagenome w as identified. Besides that,w e also predicted that some genes could encode the cellulosome component. Compared w ith G H genes in the gastrointestinal metagenome of other species,the proportions of cellulose,hemicellulase and debranching enzyme w ere similar betw een Haizi buffalo and dairy cow. These results demonstrate that buffalo rumen is considerably enriched in functional microorganisms and enzymes involved in lignocellulose degradation w ith great prospects to obtain enzyme genes that may be applied in the industry.更多还原