The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, People's Republic of China.
Appl Biochem Biotechnol. 2023 Oct;195(10):6003-6019. doi: 10.1007/s12010-023-04353-9. Epub 2023 Feb 4.
Acetic acid bacteria have a remarkable capacity to cope with elevated concentrations of cytotoxic acetic acid in their fermentation environment. In particular, the high-level acetate tolerance of Acetobacter pasteurianus that occurs in vinegar industrial settings must be constantly selected for. However, the improved acetic acid tolerance is rapidly lost without a selection pressure. To understand genetic and molecular biology of this acquired acetic acid tolerance in A. pasteurianus, we evolved three strains A. pasteurianus CICIM B7003, CICIM B7003-02, and ATCC 33,445 over 960 generations (4 months) in two initial acetic acids of 20 g·L and 30 g·L, respectively. An acetic acid-adapted strain M20 with significantly improved specific growth rate of 0.159 h and acid productivity of 1.61 g·L·h was obtained. Comparative genome analysis of six evolved strains revealed that the genetic variations of adaptation were mainly focused on lactate metabolism, membrane proteins, transcriptional regulators, transposases, replication, and repair system. Among of these, lactate dehydrogenase, acetolactate synthase, glycosyltransferase, ABC transporter ATP-binding protein, two-component regulatory systems, the type II toxin-antitoxin system (RelE/RelB/StbE), exodeoxyribonuclease III, type I restriction endonuclease, tRNA-uridine 2-sulfurtransferase, and transposase might collaboratively contribute to the improved acetic acid tolerance in A. pasteurianus strains. The balance between repair factors and transposition variations might be the basis for genomic plasticity of A. pasteurianus strains, allowing the survival of populations and their offspring in acetic acid stress fluctuations. These observations provide important insights into the nature of acquired acetic acid tolerance phenotype and lay a foundation for future genetic manipulation of these strains.
醋酸菌具有显著的应对发酵环境中细胞毒性乙酸浓度升高的能力。特别是在醋工业环境中，巴氏醋酸杆菌（Acetobacter pasteurianus）具有高水平的耐乙酸能力，这种能力必须不断进行选择。然而，如果没有选择压力，这种提高的乙酸耐受性会迅速丧失。为了了解巴氏醋酸杆菌获得耐乙酸能力的遗传和分子生物学特性，我们在两种初始乙酸浓度分别为 20 g·L 和 30 g·L 的条件下，经过 960 代（4 个月）的进化，得到了三株巴氏醋酸杆菌 CICIM B7003、CICIM B7003-02 和 ATCC 33,445。我们获得了一株具有显著提高的比生长速率（0.159 h）和产酸速率（1.61 g·L·h）的乙酸适应菌株 M20。对 6 株进化菌株的比较基因组分析表明，适应的遗传变异主要集中在乳酸代谢、膜蛋白、转录调控因子、转座酶、复制和修复系统。其中，乳酸脱氢酶、乙酰乳酸合酶、糖基转移酶、ABC 转运蛋白 ATP 结合蛋白、双组分调控系统、II 型毒素-抗毒素系统（RelE/RelB/StbE）、核酸外切酶 III、I 型限制内切酶、tRNA-尿嘧啶 2-硫基转移酶和转座酶可能共同有助于提高巴氏醋酸杆菌的耐乙酸能力。修复因子和转座变异之间的平衡可能是巴氏醋酸杆菌菌株基因组可塑性的基础，使种群及其后代能够在乙酸胁迫波动中生存。这些观察结果为获得性耐乙酸表型的本质提供了重要的见解，并为未来对这些菌株进行遗传操作奠定了基础。
