甘蔗尾青贮核心发酵菌群和代谢物演替规律及其对水牛瘤胃细菌多样性的影响

Guangxi is the main planting area for sugarcane in china and the world. About 14m tonnes of sugarcane tops is available each year. Our preliminary study showed that yeast are associated with fermentation since the beginning of sugarcane tops ensiling, and the lactic acid bacteria composition of sugarcane tops` silage also differ from that of maize stover silage. Study on the succession of core microbiomes and metabolites throughout the process of sugarcane tops ensiling will give a deep knowledge to sugarcane tops ensilage. This project will take sugarcane tops as research target, using metabolic method and culture-independent technique based on high throughput gene-sequencing technologies and we focus on the initial microorganism of sugarcane tops ensilage and external environmental temperature and humidity during ensilage period these two factors, and observe the two factors affect the succession of lactic acid bacteria and yeast and main metabolites during ensiling and aerobic exposure periods. Based on the above research we can find the microbiomes and metabolites which can benefit the sugarcane tops fermentation, and which can indicate the aerobic deterioration. Meanwhile, we contrast the lactic acid bacteria composition between high-quality and low-quality sugarcane tops silage, then we set up new lactic acid bacteria combination based on high-quality sugarcane tops silage microbiome communities, then we inoculate this lactic acid bacteria combination into sugarcane tops silage, and study the effects of this sugarcane tops silage on the ruminal bacteria diversity of water buffalo. This project will clarify the regulation of sugarcane tops silage between core microorganism and metabolite, and illustrates the influences of sugarcane tops silage on the ruminal microorganism diversity of water buffalo. These work will also provide new strategy to regulate sugarcane tops ensilage.

广西年产甘蔗尾约1400万吨。前期研究显示，甘蔗尾富含蔗糖，自然青贮始终伴随着酵母菌发酵，且其青贮乳酸菌组成有别于玉米秸秆青贮。研究甘蔗尾青贮核心发酵菌群和代谢物演替规律，是深入理解甘蔗尾青贮的基础。本项目拟采用微生物代谢组学和高通量测序技术相结合的方法，探讨甘蔗尾青贮起始微生物组成以及外界环境温湿度对其青贮动态发酵过程、暴露空气后不同时段乳酸菌、酵母菌演替规律，代谢物的消长规律，挖掘促进甘蔗尾青贮发酵及指示有氧变质的微生物菌种及生物标志物。同时，对比优质与劣质甘蔗尾青贮中乳酸菌组成差异，应用存在于优质青贮中的优势乳酸菌菌株配置复合菌液，考察该复合菌液扰动甘蔗尾青贮菌群和代谢物的效果，最后，开展动物实验来验证添加乳酸菌青贮甘蔗尾对水牛瘤胃细菌多样性的影响。此研究将揭示影响甘蔗尾青贮品质的核心菌群与代谢物演替规律，阐明甘蔗尾青贮对水牛瘤胃细菌组成的影响，亦为定向调控甘蔗尾青贮提供新策略。

广西甘蔗尾年产量超过1400万吨。前期研究显示，甘蔗尾富含蔗糖，其自然青贮始终伴随着酵母菌发酵，且其青贮乳酸菌组成有别于玉米秸秆青贮。研究甘蔗尾青贮核心发酵菌群和代谢物演替规律，是深入理解甘蔗尾青贮的基础。本项目以甘蔗尾为原料结合微生物组学的方法研究了在广西在热带季风性和亚热带季风性气候条件下自然青贮过程中历经低温高湿和高温高湿环境波动下对其自然青贮及有氧暴露过程中微生物的群落的演替规律以及开展了其与常见饲草包括玉米秸秆和象草通过先灭菌在重新构建附生微生物后青贮对其青贮品质影响的研究，同时，对比探究了甘蔗尾青贮中筛选并制成重配复合菌液与商品化菌酶复合制剂对甘蔗尾青贮品质及其对瘤胃微生物的影响。研究表明：1）青贮过程中面临高温环境时更可能导致丁酸发酵，而在其有氧暴露后可筛选利用沙雷氏菌抑制曲霉菌、枝孢菌和镰刀菌从而提高青贮有氧稳定性。2）以乳酸菌为主的附生微生物复合菌液（如玉米秸秆附生微生物）可通过增加青贮乳酸含量，抑制有氧暴露下酵母菌繁殖的方式提升青贮品质。3）甘蔗尾青贮中筛选并制成重配复合菌液更能促进青贮乳酸杆菌生长和抑制毕赤酵母繁殖且干物质和乳酸含量更高，其经饲喂后也能调节瘤胃中主要微生物组成。经过上述系列研究，首先揭示了甘蔗尾青贮过程及有氧暴露后微生物菌群及其代谢产物的演替规律，同时挖掘出具有抑制青贮有氧暴露快速变质和改善甘蔗尾青贮的特定功能性微生物（如沙雷氏菌等）及其标志性代谢产物（如乳酸等），其次初步证实了灭菌-重构附生微生物的方法在研究微生物菌群与青贮原料特性之间的相互作用的可行性，并筛选获得高效改善的甘蔗尾青贮的复合菌液。最后明确了调控甘蔗尾附生乳酸菌的组成可改善青贮中微生物组成进而提高甘蔗尾青贮品质，也进一步阐明了经过乳酸菌调控的甘蔗尾青贮对水牛瘤胃微生物存在一定的影响，亦为定向调控甘蔗尾青贮提供新策略。项目成果正式发表论文13篇，培养硕士研究生5人。