Komagataeibacter hansenii HDM1-3 (K. hansenii HDM1-3) has been widely applied for producing bacterial cellulose (BC). The yield of BC has been frequently limited by the acidification during sugar metabolism, due to the generation of organic acids such as acetic acid. In this study, the acid resistance mechanism of K. hansenii HDM1-3 has been investigated from the aspect of metabolic adaptability of cell membrane fatty acids. Firstly, we observed that the survival rate of K. hansenii HDM1-3 was decreased with lowered pH values (adjusted with acetic acids), accompanied by increased leakage rate. Secondly, the cell membrane adaptability in response to acid stress was evaluated, including the variations of cell membrane fluidity and fatty acid composition. The proportion of unsaturated fatty acids was increased (especially, C18-1w9c and C19-Cyc), unsaturation degree and chain length of fatty acids were also increased. Thirdly, the potential molecular regulation mechanism was further elucidated. Under acid stress, the fatty acid synthesis pathway was involved in the structure and composition variations of fatty acids, which was proved by the activation of both fatty acid dehydrogenase (des) and cyclopropane fatty acid synthase (cfa) genes, as well as the addition of exogenous fatty acids. The fatty acid synthesis of K. hansenii HDM1-3 may be mediated by the activation of two-component sensor signaling pathways in response to the acid stress. The acid resistance mechanism of K. hansenii HDM1-3 adds to our knowledge of the acid stress adaptation, which may facilitate the development of new strategies for improving the industrial performance of this species under acid stress.

中文翻译：

---

汉逊Komagataeibacter Hanmii HDM1-3的细胞膜脂肪酸的代谢适应性变化改善了耐酸性和在酸性环境中的存活率。

汉氏Komagataeibacter HDM1-3（K. hansenii HDM1-3）已被广泛用于生产细菌纤维素（BC）。由于有机酸（例如乙酸）的产生，糖代谢过程中的酸化作用经常限制了BC的产量。在这项研究中，已从细胞膜脂肪酸的代谢适应性方面研究了汉逊氏酵母HDM1-3的耐酸机理。首先，我们观察到随着pH值的降低（用乙酸调节），汉森氏假单胞菌HDM1-3的存活率降低，同时泄漏率增加。其次，评估了细胞膜对酸胁迫的适应性，包括细胞膜流动性和脂肪酸组成的变化。不饱和脂肪酸的比例有所增加（尤其是C18-1w9c和C19-Cyc），脂肪酸的不饱和度和链长也增加。第三，进一步阐明了潜在的分子调控机制。在酸胁迫下，脂肪酸的合成途径参与了脂肪酸的结构和组成变化，这通过脂肪酸脱氢酶（des）和环丙烷脂肪酸合酶（cfa）基因的激活以及添加来证明。外源脂肪酸。汉逊氏酵母HDM1-3的脂肪酸合成可以通过响应于酸胁迫的两组分传感器信号传导途径的活化来介导。K.hansenii HDM1-3的抗酸机理增加了我们对酸胁迫适应性的认识，这可能有助于开发新的策略以改善该物种在酸胁迫下的工业性能。