State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, China; College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816, China; College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
Bioresour Technol. 2022 Sep;359:127382. doi: 10.1016/j.biortech.2022.127382. Epub 2022 May 26.
Microbial production of poly-γ-glutamic acid (γ-PGA) from non-food raw materials is a promising alternative to food feedstocks-based biosynthesis. A superior cell factory of Bacillus amyloliquefaciens for the efficient synthesis of γ-PGA from crude glycerol was constructed through systematic metabolic engineering. Firstly, some phase-dependent promoters were screened from B. amyloliquefaciens, which can be used for fine regulation of subsequent metabolic pathways. Secondly, the glycerol utilization pathway and the γ-PGA synthesis pathway were co-optimized utilizing the above-screened promoters, which increased the titer of γ-PGA by 1.75-fold. Then, the titer of γ-PGA increased to 15.6 g/L by engineering transcription factors degU and blocking competitive pathways. Finally, combining these strategies with an optimized fermentation process, 26.4 g/L γ-PGA was obtained from crude glycerol as a single carbon source (a 3.72-fold improvement over the initial strain). Overall, these strategies will have great potential for synthesizing other products from crude glycerol in B. amyloliquefaciens.
从非食用原料生产聚-γ-谷氨酸（γ-PGA）是替代基于食用原料的生物合成的一种很有前途的方法。通过系统的代谢工程，构建了一种优秀的解淀粉芽孢杆菌细胞工厂，可从粗甘油高效合成 γ-PGA。首先，从解淀粉芽孢杆菌中筛选出一些与生长阶段相关的启动子，可用于精细调控后续的代谢途径。其次，利用上述筛选出的启动子对甘油利用途径和 γ-PGA 合成途径进行了协同优化，使 γ-PGA 的产量提高了 1.75 倍。然后，通过工程化转录因子 degU 和阻断竞争途径，将 γ-PGA 的产量提高到 15.6 g/L。最后，通过结合这些策略和优化的发酵工艺，从粗甘油作为单一碳源获得了 26.4 g/L 的 γ-PGA（比初始菌株提高了 3.72 倍）。总的来说，这些策略将在解淀粉芽孢杆菌中利用粗甘油合成其他产品方面具有很大的潜力。
