云南特有独龙牛瘤胃微生物高效纤维物质降解基因资源及其功能解析

Gayal is the specific cattle in Yunnan Province, with the typical geographical characteristics of the original rare breeds. Preliminary studies showed that they fed on low quality crude fiber materials still can obtain better growth and weight gain, rumen total viable bacteria, cellulose degrading bacteria and in vitro dry matter digestibility of bamboo, straw and barley straw in Gayal was significant higher than Yunnan yellow cattle. These phenomena suggested Gayal has unique rumen microbial flora and existence of efficient fiber degrading microorganisms. Therefore, the rumen microbial metagenomics and metatranscriptomics sequencing libraries will be build and theirs information’s will be obtained through high-throughput sequencing of Gayal and Yunnan yellow cattle under the native environments in the project. Following by use of the Basic Local Alignment Search Tools (BLAST) compare with various functional databases (Nr, COG, KEGG) for functional genomics annotations of species composition, community structure, metabolic pathway and genes functional analysis. Meanwhile, the characteristic genes will be determine by compare Gayal and Yunnan yellow cattle rumen microbial communities; and the differential expression genes will be investigate by GO functional enrichment method and KEGG metabolic pathway method through differential expression analysis of transcriptome; and the effects of environmental adaptation on genes will be analyzed. The key metabolic pathways, signaling pathways and genes related to fiber material-degrading for Gayal rumen microorganisms will be analyzed combining metagenomics with metatranscriptomics, and the related functional enzyme genes of fiber material degradation will be screened. Above studies will help to obtain highly activity fiber material-degrading enzyme genes; and the related genes cloning and expression will be studied in vitro according to obtained enzyme genes sequences. and the related genes cloning and expression will be studied in vitro according to obtained enzyme genes. Results would provide an effective way and new solutions for efficient use of the crude feed and promote the development of new enzymes, which have great significance to the development of unique biodiversity resources in Yunnan Province.

独龙牛是云南特有的半野生珍稀牛种。前期研究发现独龙牛采食竹子等高纤维物质仍能获得良好的生长和增重；瘤胃内总活细菌、纤维降解菌及对竹子、稻草和大麦秸等干物质体外消化率显著高于同一生境的云南黄牛。这一现象提示独龙牛具有独特的瘤胃微生物区系和存在高效降解纤维物质的微生物。因此，本项目构建原生境下独龙牛和云南黄牛瘤胃微生物宏基因组和宏转录组测序文库后高通量测序，与各功能数据库（Nr、KEGG、COG等）进行比对，对物种组成、群落结构、代谢通路及功能基因等进行分析；分析不同牛种中的特征基因和差异表达基因，分析环境和地理适应对基因的影响；以基因组与转录组关联分析揭示独龙牛瘤胃微生物与纤维物质降解相关的关键代谢通路及关键基因，挖掘纤维物质降解相关酶类功能基因；开展相关纤维物质降解酶类基因的克隆和表达研究。研究结果可对粗饲料的高效利用和促进新型酶制剂的开发提供新的解决思路。

独龙牛是云南特有的半野生珍稀牛种，具有独特的瘤胃微生物区系。项目构建原生境下独龙牛和云南黄牛瘤胃微生物宏组学测序文库后高通量测序，与各功能数据库（Nr、KEGG、COG等）进行比对，对物种组成、群落结构、代谢通路及功能基因等进行分析。揭示了独龙牛瘤胃微生物物种组成与丰度，在物种组成上，独龙牛与黄牛瘤胃中都是以细菌为主，与黄牛相比独龙牛瘤胃中真核生物含量较高；阐明了独龙牛功能基因组成及乙酸和丁酸代谢途径代谢特征；筛选了粗纤维降解相关酶、粗纤维降解结合蛋白、粗纤维降解功能微生物；认为碳水化合物降解酶的差异及各牛种独有的家族是导致独龙牛和黄牛对纤维物质降解的主要差异原因之一，这些水解酶家族在瘤胃纤维物质降解中起到积极作用，构建了独龙牛与黄牛瘤胃微生物粗纤维降解模型；获得了高活性的纤维物质降解酶。