一种自下而上的合成微生物组理性构建策略，用于郫县豆瓣发酵剂设计

A bottom-up strategy for constructing a synthetic microbiome and its application to the design of Pixian Douban starter

摘要:

【目的】提出一种合成微生物组的理性构建策略，用于构建郫县豆瓣蚕豆醅初始发酵的微生物组合菌剂。【方法】采取自下而上的合成微生物组理性构建策略，以相对丰度、频率和特征向量中心度作为核心微生物属的选择指标，分析确定蚕豆醅发酵核心微生物；设计模拟原位体系的全合成培养基，并利用该培养基快速、稳定地检测核心微生物包括产香性能在内的发酵特征。基于核心微生物的产香互补性能进行双菌组合发酵实验，结合核心微生物之间的生长相互作用，设计三菌组合发酵菌剂并验证其发酵性能。【结果】本研究确定并分离了郫县豆瓣蚕豆醅发酵过程中的 9种核心微生物。检测核心微生物产生的挥发性风味化合物，发现酵母菌类、乳酸菌类和其他类微生物之间存在产香互补关系。然后，结合微生物间的生长抑制关系设计了由乳酸片球菌、肉葡萄球菌及异变假丝酵母组成的三菌组合菌剂。与企业原位发酵样品相比，三菌组合菌剂产生的挥发性化合物数量达到原位样品的63.1%，化合物种类结构较为相似。与原位样品相比，组合菌剂样品氨基酸态氮浓度提升了21.8%。【结论】本研究提出了一种自下而上的合成微生物组理性构建策略，基于此策略设计了郫县豆瓣蚕豆醅发酵组合菌剂。使用该组合菌剂作为起始发酵剂发酵的郫县豆瓣蚕豆醅具有良好的风味谱和优异的氨基酸态氮水平。本研究在合成微生物组构建与发酵食品工艺改造方面具有较大的科学与应用价值。

Abstract:

[Objective] This study aimed to construct a synthetic microbiome which would be used as a starter for Pixian Douban (broad bean paste) fermentation.[Methods] We analyzed core microorganisms of Pixian Douban fermentation by the combined indicators,including microbial relative abundance,frequency and eigenvector centrality.Then a fully synthetic medium which simulated the in situ fermentation system was designed and used to explore the growth and aroma-producing characteristics of core microorganisms.According to the complementary aroma-producing characteristics of core microorganisms,a two-strain co-fermentation experiment was conducted.Moreover,taking the microbial interactions into account,we designed a three-strain community and verified its fermentation performance.[Results] In this study,9 microorganisms were identified and isolated from Pixian Douban as the core microorganisms.Then the volatile profiles of these core microorganisms were detected and a complementary aroma-producing relationship was found among yeasts,lactic acid bacteria and other microorganisms.Combining the growth inhibition relationship among microorganisms,we formed a three-strain combined inoculum,including Pediococcus acidilactici,Staphylococcus carnosus and Candida versatilis.With the three-strain community as the fermentation starter,the fermentation samples showed 63.1% similarity of flavor compounds and 21.8% improvement of amino acid nitrogen content compared to the in situ samples.[Conclusion] A bottom-up strategy for constructing a synthetic microbiome community was proposed,and a three-strain microbial community as the starter for Pixian Douban production was built.This study is valuable for synthetic microbiome construction and fermentation process optimization.