Li Yongda, Yan Yongli, Chen Jihong, Zhang Zhen, Hu Wei
College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, P.R. China.
Department of Biophysics, Institute of Modern Physics, Chinese, Academy of Sciences, Lanzhou, P.R. China.
Biotechnol J. 2023 Dec;18(12):e2300110. doi: 10.1002/biot.202300110. Epub 2023 Aug 9.
Environmental stress resistance is still a bottleneck for economical process for l-lactic acid fermentation. Chronological lifespan (CLS) extension has represented a promising strategy for improving stress resistance of microbial cell factories.
In this study, addition of anti-aging drug cysteine, a kind of extending CLS of microbial cell factories, was systematically evaluated on cell viability and l-lactic acid production in Bacillus coagulans CICC 23843. The results revealed that 16 mm l-cysteine supplement significantly improved l-lactic acid titer in B. coagulans. The enhanced total antioxidant capacity (T-AOC) and key enzymes activities involving in glycolytic pathway as well as differentially expressed genes involved in cysteine synthesize and cysteine precursor synthesize pathways, and fatty acid degradation pathway may help to further understand the relative mechanism of l-cysteine effect on improving l-lactic acid accumulation. Finally, based on 16 mm l-cysteine supplement, a final l-lactic acid titer of 130.5 g L with l-lactic acid productivity of 4.07 g L h and the conversion rate of 0.94 g g total sugar was achieved in a 5 L bioreactor.
This study provided a valuable option for engineering lactic acid bacteria lifespan for enhancement of lactic acid yield.
环境抗逆性仍然是L-乳酸发酵经济化生产过程中的一个瓶颈。延长时序寿命（CLS）已成为提高微生物细胞工厂抗逆性的一种有前景的策略。
在本研究中，系统评估了添加抗衰老药物半胱氨酸（一种延长微生物细胞工厂CLS的物质）对凝结芽孢杆菌CICC 23843细胞活力和L-乳酸产量的影响。结果表明，添加16 mM L-半胱氨酸可显著提高凝结芽孢杆菌中L-乳酸的滴度。总抗氧化能力（T-AOC）增强、糖酵解途径中关键酶的活性以及半胱氨酸合成和半胱氨酸前体合成途径以及脂肪酸降解途径中差异表达的基因，可能有助于进一步理解L-半胱氨酸提高L-乳酸积累的相关机制。最后，基于添加16 mM L-半胱氨酸，在5 L生物反应器中实现了最终L-乳酸滴度为130.5 g/L、L-乳酸生产率为4.07 g/(L·h)以及总糖转化率为0.94 g/g的结果。
本研究为通过工程手段延长乳酸菌寿命以提高乳酸产量提供了一个有价值的选择。
