基于元基因组分析的镇江香醋风味合成途径构建

Zhenjiang aromatic vinegar is one of the Chinese traditional leading brands of vinegar， fermented with various microorganisms in open and solid-state environment. Its flavor formation is very complex, which includes a series of biochemical processes that the microflora participated in. In our previous study, changes of microbial community and representative flavor，such as organic acids and volatile component, during the acetic acid fermentation process of Zhenjiang aromatic vinegar have been investigated. This study aims to further analyze the flavor-forming metabolic pathways from ethanol and construct the metagenome-scale flavor metabolic network based on the metagenomic analysis and existed metabolic pathway database. Furthermore, the functional microbes in the formation of vinegar flavor would be extensively studied. Results of the project should be benefit to understand the process mechanism of Chinese traditional fermented vinegars, and provide the theoretical foundation for the research and development of venigar-producing functional microbes.

镇江香醋是我国固态开放式多菌种混合发酵食醋典型代表，其风味形成是一个涉及多种微生物作用的十分复杂的生化过程。本项目以我国镇江香醋为研究对象，在研究其醋酸发酵过程中微生物群落结构及其代表性风味化合的基础上，利用元基因组测序并借鉴对已有的相关风味物质形成过程的认识，深入解析以酒精为底物合成镇江香醋典型有机酸及挥发性风味物质形成代谢途径并构建其元基因组规模的风味代谢网络，明晰主要功能微生物在其风味合成中的作用，为更好地理解我国传统固态发酵食醋工艺机理，指导酿醋功能菌群开发利用与优化提供科学的理论基础。

本项目以镇江香醋作为多菌种固态发酵的典型代表，构建了基于宏基因组序列分析的镇江香醋20种主要风味物质的代谢途径，研究了酿造过程中微生物菌群与风味物质合成之间的关系。结果表明镇江香醋酿造过程中微生物菌群结构复杂、且处于动态变化中；相关性分析表明细菌菌群对风味物质合成的贡献大于真菌菌群，采用有效组分和基于系统发育的算法对元基因组测序进行了物种和物质合成功能的关联分析，获得了微生物与主要风味物质合成之间的映射关系；进一步分析了上述代谢网络中重要的物质乙偶姻、双乙酰、异戊醇、四甲基吡嗪以及丁二醇等，主要的氨基酸，如亮氨酸和缬氨酸等的合成途径。通过本项目研究，构建了食醋中微生物与风味合成之间的功能分析技术，明晰了镇江香醋主要风味物质的合成代谢途径及微生物群落中参与上述物质合成的主要微生物种类，更好地阐释了固态发酵食醋的酿造机理，为指导酿醋功能菌群的开发利用提供了理论基础。