School of Bioengineering, Dalian University of Technology, Dalian 116024, China.
Ningbo Research Institute, Dalian University of Technology, Ningbo 315000, China.
Int J Mol Sci. 2022 Mar 21;23(6):3406. doi: 10.3390/ijms23063406.
Bioethanol from lignocellulosic biomass is a promising and sustainable strategy to meet the energy demand and to be carbon neutral. Nevertheless, the damage of lignocellulose-derived inhibitors to microorganisms is still the main bottleneck. Developing robust strains is critical for lignocellulosic ethanol production. An evolved strain with a stronger tolerance to formate and acetate was obtained after adaptive laboratory evolution (ALE) in the formate. Transcriptional analysis was conducted to reveal the possible resistance mechanisms to weak acids, and coding for formate dehydrogenase was selected as the target to verify whether it was related to resistance enhancement in F3. Engineered FA with overexpression exhibited boosted tolerance to both formate and acetate, but the resistance mechanism to formate and acetate was different. When formate exists, it breaks down by formate dehydrogenase into carbon dioxide (CO) to relieve its inhibition. When there was acetate without formate, FDH1 converted CO from glucose fermentation to formate and ATP and enhanced cell viability. Together, overexpression alone can improve the tolerance to both formate and acetate with a higher cell viability and ATP, which provides a novel strategy for robustness strain construction to produce lignocellulosic ethanol.
从木质纤维素生物质中生产生物乙醇是一种很有前途且可持续的策略，可以满足能源需求并实现碳中和。然而，木质纤维素衍生抑制剂对微生物的损害仍然是主要的瓶颈。开发具有较强耐受力的菌株对于木质纤维素乙醇生产至关重要。经过在甲酸盐中的适应性实验室进化（ALE），获得了一种对甲酸盐和乙酸盐具有更强耐受性的进化菌株。进行了转录分析以揭示对弱酸的可能抗性机制，并选择甲酸脱氢酶的编码作为目标，以验证其是否与 F3 中的增强抗性有关。过表达的工程 FA 表现出对甲酸盐和乙酸盐的耐受性增强，但对甲酸盐和乙酸盐的抗性机制不同。当甲酸盐存在时，它会被甲酸脱氢酶分解成二氧化碳（CO）以缓解其抑制作用。当没有甲酸盐但有乙酸盐时，FDH1 将来自葡萄糖发酵的 CO 转化为甲酸盐和 ATP，从而提高细胞活力。总之，单独过表达可以提高对甲酸盐和乙酸盐的耐受性，同时具有更高的细胞活力和 ATP，为生产木质纤维素乙醇的稳健菌株构建提供了一种新策略。
