苗家酸肉发酵过程中微生物菌群结构的动态变化与香气物质形成的关系

Miaojia Sour meat, a Chinese traditional fermented meat product, is favored by consumers for its prominent national characteristics and unique flavor. However, there are some problems with its industrial products such as aroma deficiency and poor safety. Although the predecessors has obtained some research results on the microbial diversity, dynamic changes of bacteria community structure and their relation with the formation of aroma substances during the process of Sour meat production, the obtained information are still insufficient and unsystematic, for the limitation of the adopted methods. In this project, we intend to analyze the species, quantities and phylogenetic diversity of microbial during the traditional fermentation of Sour meat by methods of metagenomics and metatranscriptomics, in order to clarify the community structures, the abundances and dynamic changes of microbes at the various stages of Sour meat traditional fermentation and investigate the relation between the microbial metabolism activities and the formation of aroma substances of Sour meat. Meanwhile, we will try to discover the genes related to aroma of uncultivable microorganisms, and find the cultivation methods for uncultivable aroma-producing microorganisms from Miaojia Sour meat. This project will further reveal the microbial diversity in Miaojia Sour meat fermentation, and illuminate the relation between the composition and dynamic changes of microbial community and the formation of Sour meat aroma substances. This project will provide theoretical basis for the improvement of production process, the control of product quality and the exploration of starter cultures for Sour meat products.

苗家酸肉是富有民族特色、风味独特的传统发酵肉制品，深受消费者的青睐，但存在工业化产品香味不足、安全性差等问题。虽然前人对其传统加工过程中的微生物多样性、菌群演替规律及其与香味物质形成的相关性等有了一定的研究，但限于所采用方法的局限性，研究不够深入和系统。因此，本课题拟以宏基因组学方法和宏转录组学方法分析酸肉传统发酵过程中微生物的种类、数量和系统发育多样性，阐明酸肉加工过程中微生物菌群结构、种群丰度及动态变化规律，探讨不同发酵阶段微生物代谢活动与酸肉香味物质形成的关系；同时，挖掘不可培养微生物的产香功能基因，构建不可培养产香微生物的培养方法。本课题的开展，将更加深入系统地揭示酸肉中的微生物多样性，阐明微生物群落的种类、数量和优势菌群的演替与酸肉香味形成的关系，可为酸肉制品生产工艺的改善、产品质量的控制和优良功能发酵剂的开发提供理论依据。

传统发酵肉制品的质量不稳定，安全性差，工业化生产困难,而人工接种方法生产的发酵肉制品的风味很难与传统发酵肉制品媲美，因此对传统发酵肉制品的微生物菌群构成和演变规律进行全面而深入的了解，在此基础上探讨微生物区群落动态变化与传统发酵肉制品的香气物质形成的关系和发掘产香功能性发酵剂，对解决传统发酵肉制品工业化产品风味不足问题有重要的理论意义和实际价值。本项目从分析苗家酸肉微生物多样性入手，釆用16S rDNA高通量测序技术研究酸肉中细菌的种类、丰度和系统发育多样性，阐明了苗家酸肉发酵过程中细菌群落结构、种群丰度和动态变化规律；同时，采用SDE法和SPME 法提取不同发酵时期酸肉的香气物质，经GC-MS法分析苗家酸肉香气成分，揭示了苗家酸肉产香时期的细菌群落结构；对不同地区和不同发酵罐深度的酸肉中细菌群落结构、种群丰度进行了比较，揭示其优势菌群，发现酸肉中共有细菌菌群；对产香微生物进行分离纯化，挖掘出7株产香微生物。本项目揭示了湘西苗家酸肉中细菌菌群种类及动态变化规律，以及细菌的种类、数量和优势菌群的消长对酸肉香气形成的影响，为苗家酸肉制品生产工艺的改善、产品质量的控制和优良性状发酵剂的开发提供了理论依据和种质资源。