Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, 769 008, Odisha, India.
Appl Microbiol Biotechnol. 2023 Jun;107(11):3355-3374. doi: 10.1007/s00253-023-12529-w. Epub 2023 Apr 24.
Acid-tolerant bacteria such as Streptococcus mutans, Acidobacterium capsulatum, Escherichia coli, and Propionibacterium acidipropionici have developed several survival mechanisms to sustain themselves in various acid stress conditions. Some bacteria survive by minor changes in the environmental pH. In contrast, few others adapt different acid tolerance mechanisms, including amino acid decarboxylase acid resistance systems, mainly glutamate-dependent acid resistance (GDAR) and arginine-dependent acid resistance (ADAR) systems. The cellular mechanisms of acid tolerance include cell membrane alteration in Acidithiobacillus thioxidans, proton elimination by F-F-ATPase in Streptococcus pyogenes, biofilm formation in Pseudomonas aeruginosa, cytoplasmic urease activity in Streptococcus mutans, synthesis of the protective cloud of ammonia, and protection or repair of macromolecules in Bacillus caldontenax. Apart from cellular mechanisms, there are several acid-tolerant genes such as gadA, gadB, adiA, adiC, cadA, cadB, cadC, speF, and potE that help the bacteria to tolerate the acidic environment. This acid tolerance behavior provides new and broad prospects for different industrial applications and the bioremediation of environmental pollutants. The development of engineered strains with acid-tolerant genes may improve the efficiency of the transgenic bacteria in the treatment of acidic industrial effluents. KEY POINTS: • Bacteria tolerate the acidic stress by methylating unsaturated phospholipid tail • The activity of decarboxylase systems for acid tolerance depends on pH • Genetic manipulation of acid-tolerant genes improves acid tolerance by the bacteria.
耐酸细菌，如变形链球菌、荚膜拟杆菌、大肠杆菌和丙酸丙酸杆菌，已经开发出几种生存机制来在各种酸应激条件下维持自身。一些细菌通过环境 pH 值的微小变化而存活。相比之下，少数细菌适应不同的耐酸机制，包括氨基酸脱羧酶酸抗性系统，主要是谷氨酸依赖的酸抗性 (GDAR) 和精氨酸依赖的酸抗性 (ADAR) 系统。耐酸的细胞机制包括嗜酸硫杆菌细胞膜的改变、酿脓链球菌中 F-F-ATP 酶的质子消除、铜绿假单胞菌生物膜的形成、变形链球菌细胞质脲酶活性、氨的保护性云的合成以及 Bacillus caldontenax 中大分子的保护或修复。除了细胞机制外，还有几种耐酸基因，如 gadA、gadB、adiA、adiC、cadA、cadB、cadC、speF 和 potE，它们有助于细菌耐受酸性环境。这种耐酸行为为不同的工业应用和环境污染物的生物修复提供了新的广阔前景。具有耐酸基因的工程菌株的开发可以提高转基因细菌在处理酸性工业废水方面的效率。关键点：
细菌通过甲基化不饱和磷脂酰尾来耐受酸性应激。
脱羧酶系统的酸耐受活性取决于 pH 值。
细菌耐酸基因的遗传操作可提高其耐酸能力。
