基于氨基酸调控的酱油源融合魏斯氏菌高盐胁迫盐析响应机制研究

魏斯氏菌是食品混菌发酵体系常见的乳酸菌，其作为酱油酿造的优势细菌与风味和营养密切相关，但发酵体系的高盐胁迫限制其存活和发挥作用。前期研究发现，酱油源魏斯氏菌在体外高盐乳酸菌培养基中耐盐性显著降低，而外源添加氨基酸可提高菌株的耐盐性，但作用机制仍不清楚。氨基酸作为耐盐菌抗高盐胁迫的相容性溶质，推测其通过盐析机制调控魏斯氏菌的耐盐性，以促进菌株在酱油酿造中发挥作用。因此，本项目拟以自主筛选的融合魏斯氏菌为研究对象，从酱油体系中筛选调控菌株耐盐性的关键氨基酸；利用分子生物学和组学技术，考察菌株在高盐胁迫下氨基酸添加与否的胞内微环境、细胞膜特性、胞内代谢产物和蛋白质的差异；基于盐析策略的细胞应激反应，整体解析氨基酸调控融合魏斯氏菌抗高盐胁迫的分子机制，为靶向调控魏斯氏菌提升酱油品质提供科学依据，促进融合魏斯氏菌在传统发酵食品的有效应用。

Weissella, a representing lactic acid bacteria, is widely observed in a diverse bacterial community in many types of fermented foods. As the dominant group of bacteria during soy sauce production, Weissella contribute to the formation of soy sauce flavor and nutrition. However, the high salt stress conditions will have a great impact on the normal physiological function of Weissella. Our research group found that the Weissella isolated from high salt fermentation soy sauce has low salinity tolerance on MRS medium. Meanwhile, the amino acids addition could improve the salt tolerance of Weissella. Yet the regulatory mechanisms underlying the role of amino acids remain unclear. Previous studies have suggested that the amino acids are an important class of compatible solute in salt-out strategy for halotolerant bacteria to adjust to hypersaline conditions. We thus speculate that the salt-stress tolerance of Weissella is regulated by the amino acids of salt-out strategy in order to maintain physiological function during high salt soy sauce fermentation. In this study, the Weissella confusa JQ3, obtained from soy sauce mash, was investigated. Firstly, the key amino acids promoting the salt stress adaptation of the strain were screened in soy sauce. Then, the differences in intracellular micro-environment, cell membrane characterization, intracellular metabolites and proteins were investigated with or without addition of exogenous amino acids by molecular biology and omics analysis. Finally, the cellular stress responses of salt-out strategy will be analyzed to reveal the response mechanism for W. confuse JQ3 regulated by amino acids under high salt stress. These results will provide a scientific basis for the soy sauce quality improvement by Weissella regulation, and be helpful to the utilization of W. confuse for high salt food fermentations.