A novel strategy for enhancing inhibitor tolerance of gram-positive bacteria through overexpression of the peptidoglycan synthesis genes murG and mraY

• Published in: Industrial crops and products 2023-02, Vol.192, p.116112, Article 116112
• Main Authors: Qiu, Yejuan, Qiu, Zhongyang, He, Aiyong, Xu, Jiaxing, Yang, Xingcui, Zhang, Hanwen, Yang, Yuxiang, Hou, Wenyi, Li, Xiangqian, He, Jianlong
• Format: Article
• Language: English
• Subjects: Inhibitor; Lactic acid; Lignocellulose; MraY; MurG; Peptidoglycan
• ISSN: 0926-6690; 1872-633X
• DOI: 10.1016/j.indcrop.2022.116112

Pretreatment of lignocellulose can generate inhibitors, such as phenolic aldehyde, furan derivatives, and weak acids. In this study, the overexpression and co-overexpression of murG and mraY enhanced the tolerance against these inhibitors. The lactic acid production rates by Pediococcus acidilactici (pZY36e-mraY) in the presence of 0.8 g/L vanillin, 6 g/L 4-hydroxybenzaldehyde, 1.5 g/L syringaldehyde, 1.0% (v/v) furfural, and 1.0% (v/v) HMF at 24 h were 380%, 22%, 28%, 22%, and 35%, respectively, which were higher than that of the control strain. The survival rates of P. acidilactici (pZY36e-mraY) incubated for 2 h with 1.5 g/L vanillin, 10 g/L 4-hydroxybenzaldehyde, 2.5 g/L syringaldehyde, 1.8% (v/v) furfural, and 1.2% (v/v) HMF were significantly increased by 6.2, 9.9, 2.4, 6.5, and 6.0 folds, respectively. Additionally, the recombinant P. acidilactici strains could tolerate the presence of pretreated liquor from corn cob, thus promoting lactic acid production. Overexpression of murG and mraY induced high tolerance in Lactococcus lactis. The TEM images showed that the cell wall of Lactococcus lactis (pZY36e-mraY) was less damaged in the presence of inhibitors. Overall, this strategy can be employed to improve the tolerance of other gram-positive bacteria against various inhibitors. [Display omitted] •A novel strategy for improving tolerance to inhibitors was proposed.•First report on enhanced tolerance to inhibitors by murG and mraY overexpression.•MraY plays a key role in improving tolerance to lignocellulose-derived inhibitors.