State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, and School of Life Sciences, Hubei University, Wuhan 430062, China.
Zhejiang Huakang Pharmaceutical Co., Ltd., Kaihua County, Zhejiang, China.
Bioresour Technol. 2022 Apr;349:126878. doi: 10.1016/j.biortech.2022.126878. Epub 2022 Feb 19.
Inhibitors in lignocellulosic hydrolysates are toxic to Zymomonas mobilis and reduce its bioethanol production. This study revealed cysteine supplementation enhanced furfural tolerance in Z. mobilis with a 2-fold biomass increase. Transcriptomic study illustrated that cysteine biosynthesis pathway was down-regulated while cysteine catabolism was up-regulated with cysteine supplementation. Mutants for genes involved in cysteine metabolism were constructed, and metabolites in cysteine metabolic pathway including methionine, glutathione, NaHS, glutamate, and pyruvate were supplemented into media. Cysteine supplementation boosted glutathione synthesis or HS release effectively in Z. mobilis leading to the reduced accumulation of reactive oxygen species (ROS) induced by furfural, while pyruvate and glutamate produced in the HS generation pathway promoted cell growth by serving as the carbon or nitrogen source. Finally, cysteine supplementation was confirmed to enhance Z. mobilis tolerance against ethanol, acetate, and corncob hydrolysate with an enhanced ethanol productivity from 0.38 to 0.55 g∙L∙h.
木质纤维素水解物中的抑制剂对运动发酵单胞菌有毒，降低了其生物乙醇产量。本研究表明，半胱氨酸的添加增强了运动发酵单胞菌对糠醛的耐受性，使其生物量增加了 2 倍。转录组研究表明，半胱氨酸生物合成途径下调，而半胱氨酸分解代谢途径上调。构建了参与半胱氨酸代谢的基因缺失突变体，并向培养基中补充了半胱氨酸代谢途径中的代谢物，包括蛋氨酸、谷胱甘肽、NaHS、谷氨酸和丙酮酸。半胱氨酸的添加有效地促进了谷胱甘肽的合成或 HS 的释放，从而减少了糠醛诱导的活性氧（ROS）的积累，而 HS 生成途径中产生的丙酮酸和谷氨酸则作为碳源或氮源促进了细胞生长。最后，确认了半胱氨酸的添加增强了运动发酵单胞菌对乙醇、乙酸和玉米芯水解物的耐受性，使乙醇生产率从 0.38 提高到 0.55 g∙L∙h。
