Wu Caiyun, Gou Yutao, Jing Shuai, Li Wei, Ge Fanglan, Li Jiao, Ren Yao
College of life Sciences, Sichuan Normal University, Chengdu, Sichuan, China.
PLoS One. 2025 Jan 30;20(1):e0310556. doi: 10.1371/journal.pone.0310556. eCollection 2025.
Poly-gamma-glutamic acid (γ-PGA) is mainly synthesized by glutamate-dependent strains in the manufacturing industry. Therefore, understanding glutamate-dependent mechanisms is imperative. In this study, we first systematically analyzed the response of Bacillus subtilis SCP017-03 to glutamate addition by comparing transcriptomics and proteomics. The introduction of glutamate substantially altered gene expression within the central metabolic pathway of cellular carbon. Most genes in the pentose phosphate pathway (PPP), tricarboxylic acid (TCA) cycle, and energy-consuming phase of the glycolysis pathway (EMP) were down-regulated, whereas those in the energy-producing phase of glycolysis and those responsible for γ-PGA synthesis were up-regulated. Based on these findings, the fermentation conditions were optimized, and γ-PGA production was improved by incorporating oxygen carriers. In a batch-fed fermentor with glucose, the γ-PGA production reached 95.2 g/L, demonstrating its industrial production potential. This study not only elucidated the glutamate dependence mechanism of Bacillus subtilis but also identified a promising metabolic target for further enhancing γ-PGA production.
聚γ-谷氨酸（γ-PGA）在制造业中主要由依赖谷氨酸的菌株合成。因此，了解依赖谷氨酸的机制至关重要。在本研究中，我们首先通过比较转录组学和蛋白质组学，系统地分析了枯草芽孢杆菌SCP017-03对添加谷氨酸的反应。谷氨酸的引入显著改变了细胞碳中心代谢途径内的基因表达。磷酸戊糖途径（PPP）、三羧酸（TCA）循环和糖酵解途径（EMP）耗能阶段的大多数基因被下调，而糖酵解产能阶段的基因以及负责γ-PGA合成的基因则被上调。基于这些发现，优化了发酵条件，并通过加入氧载体提高了γ-PGA的产量。在装有葡萄糖的分批补料发酵罐中，γ-PGA产量达到95.2 g/L，显示出其工业生产潜力。本研究不仅阐明了枯草芽孢杆菌对谷氨酸的依赖机制，还确定了一个有前景的代谢靶点，可进一步提高γ-PGA的产量。
