凝结芽孢杆菌发酵生产L-乳酸具有产物光学纯度高、不灭菌发酵等优点，但发酵液中乳酸盐的积累限制了L-乳酸产量和生产速度的进一步提高。转录因子是具有调控基因表达功能的蛋白质分子，以转录因子为靶基因提高菌株抗逆性和生产能力取得了一定的成功，但针对凝结芽孢杆菌的研究未见报道。申请者团队前期发现了一个能够调控凝结芽孢杆菌乳酸盐抗逆性和L-乳酸生产能力的新转录因子Lrd364，在凝结芽孢杆菌中过量表达Lrd364后菌株抗乳酸盐胁迫和L-乳酸生产的能力均明显增强。在此基础上，本项目拟利用基因敲除、基因可控表达、染色质免疫共沉淀测序、转录组测序等方法解析不同表达水平下Lrd364的动态调控网络，找出与菌株抗逆性和L-乳酸生产直接关联的关键节点蛋白，阐明Lrd364调控菌株抗逆性和生产能力的分子机制，并通过最优化设计和菌株改造构建L-乳酸生产能力更强的凝结芽孢杆菌基因工程菌株。

L-Lactic acid production by Bacillus coagulans has merits of high product optical purity and non-sterilization fermentation, but further increase of L-lactic acid concentrations and production rates are limited by the accumulation of lactate during fermentation. Transcription factors are proteins that regulate gene expression. The use of transcription factors as target genes to improve the resistance and productivity of strains has achieved some success, but no report focused on Bacillus coagulans. The applicant team discovered a new transcription factor Lrd364 that can regulate lactate stress resistance and L-lactic acid production capacity of Bacillus coagulans. The overexpression of Lrd364 in B. coagulans both improved the lactate stress resistance and L-lactic acid production capacity of the strain. On this basis, the project intends to analyze the dynamic regulatory network of Lrd364 at different expression levels by gene knockout, controlled gene expression, ChIP-seq and RNA-seq, etc. The key node proteins directly related to lactate resistance and L-lactic acid production will be identified, and the molecular mechanism of Lrd364 regulating strain stress resistance and production capacity will be elucidated. Finally, a genetically engineered strain of Bacillus coagulans with enhanced L-lactic acid production capacity will be constructed through optimal design and strain modification.