乳酸菌（LAB）产生的苯乳酸（PLA）是一种公认安全的食品级生物防腐剂，提高LAB PLA产量成为当前食品保藏领域研究热点。前期研究中，项目组分离到14株产不同水平PLA植物乳杆菌，测定了其中3株全基因组序列，并发现PLA产量受培养基中葡萄糖浓度影响。本项目拟以PLA高产菌株（YM-5-2）和低产菌株（YM-4-3和AY01）为材料，确定YM-5-2对YM-4-3和AY01 PLA产量差别最大培养时间点，优化YM-5-2培养环境，在此基础上，考察高产与低产菌株、YM-5-2优化前后的基因转录和代谢物谱差异情况，构建植物乳杆菌PLA生物合成分子调控模型，并利用发酵实验验证。最后选取部分关键候选基因，利用异源表达和基因敲除技术，确定它们在PLA产生过程中的具体功能。本项目有助于深入了解LAB PLA生物合成分子调控机理及环境因子在其中的作用，为高效筛选高产菌株和系统性改造发酵菌株提供理论依据。

Phenyllactic acid (PLA) in lactic acid bacteria (LAB), generally recognized as safe, is one of food grade biological preservatives and the research to improve the yield of LAB PLA has became the hot spot of current food preservation area. In previous studies, 14 strains of Lactobacillus plantarum with different PLA yield levels were isolated and 3 of their whole genomes were sequenced by the project group. Further more, the fact that yield of PLA was influenced by the concentration of glucose in media was discovered. In this project, a high PLA yield strain (YM-5-2) and two low PLA yield strains (YM-4-3 and AY01) will be selected as study material. The incubation time of the biggest difference of the PLA yield between YM-5-2 and YM-4-3 or YM-5-2 and AY01 was determined. The culture environment of YM-5-2 was optimized. In these situations, the differences in gene transcription and metabolite profilings between YM-5-2 and YM-4-3, YM-5-2 and AY01 or between before and after optimization of YM-5-2 were investigated. The molecular regulation model of L. plantarum PLA biosynthesis was established, which was validated by fermentation experiment. At last, partial crucial candidate genes were chosen, and their specific functions in the process of PLA production were determined by heterogeneous expression and gene knock-out technology. This project will help us to understand deeply the molecular regulation mechanism of LAB PLA biosynthesis pathway and the role of environmental factors plays on, and provide theoretical basis for screening high yield strains efficiently and improve fermentation strains systematicity.