传统发酵食品的微生物菌群多样性及其对加工食品品质的影响是传统发酵食品产业发展的关键科学问题。发酵酸面团是传统馒头加工的主要发酵剂，但由于其复杂的微生态体系和菌群结构多样性，因此对馒头加工过程和风味品质的调控作用研究尚属空白。本项目重点针对我国代表性地区传统发酵酸面团开展研究，揭示微生物菌群组成及结构特征；借助宏基因组学与高通量测序技术，解析关键的共性微生物菌群与差异菌群及其与馒头风味之间关联；采用顶空固相微萃取(SPME)联合GC-O-MS或GC-MS/MS手段阐明馒头特征风味物质的形成；鉴定出调控特征风味物质产生的关键微生物群落，构建关键微生物菌群的宏基因组文库，解析功能基因簇，并借助生物信息学和代谢途径分析技术对基因进行功能注释，阐释其与特征风味物质代谢的关联。本项目开展可望揭示我国传统发酵馒头的系统生物学，明确其发酵过程中对有机物的代谢机理，探索其对馒头特征风味物质形成的调控基础。

The microbial flora in traditional fermented food is complicated and diversiform. The effect of microorganism on the quality of processed foods is the key scientific problem, which restricts the development of traditional fermented food industry. Sourdough is the starter culture for making Chinese steamed bread. Because of the complex microbial ecosystem, there are little quantitative researches about the effect of sourdough on the steamed bread processing and flavor compound forming mechanism. This project focuses on the traditional sourdough from typical area in China, to reveal the microbial flora composition and structural characteristics; using metagenomics and high-throughput sequencing technology to analysis the relationship between the microbial flora and steamed bread flavor; by using headspace solid-phase micro-extraction (SPME) and GC-O-MS or GC-MS/MS to elucidate characteristic flavor formation; constructing metagenomic library of the key microorganism, to identify the regulation characteristics of the flavor substances microbial communities, annotate and classify functional gene by bioinformatics and metabolic pathway methods; to explain its association with the flavor compounds formation. This project is expected to reveal the microbial ecological system in the traditional sourdough, make clear the metabolic pathway of organic compounds and explore the regulation mechamism on volatile flavor compounds formation during the fermentation process.