Steiner Peter, Sauer Uwe
Institute of Biotechnology, ETH Zürich, CH-8093 Zürich, Switzerland.
Biotechnol Bioeng. 2003 Oct 5;84(1):40-4. doi: 10.1002/bit.10741.
Elevated concentrations of cytotoxic acetate are found in many environmental niches, and few species are relatively resistant to acetate. In particular the high-level acetate resistance of so-called acetic acid bacteria that occurs in industrial settings must be constantly selected for. To investigate the nature of such high-level resistance, we grew the moderately acetate-resistant Acetobacter aceti wild-type and acetate-sensitive Escherichia coli in long-term continuous cultures with increasing acetate concentrations at near neutral pH. While E. coli did not acquire any significant resistance after 125 generations of selection, A. aceti evolved the capability to grow at acetate concentrations exceeding 50 g/L within 240 generations. This phenotype was found to be stable for several generations in the absence of selective pressure, hence must be genetically determined. Intracellular acetate concentrations were significantly lower in evolved A. aceti, when compared to wild-type A. aceti and E. coli, indicating that cytoplasmatic anion accumulation is an important component of acetate toxicity.
在许多环境生态位中都发现了细胞毒性乙酸盐的浓度升高，而且很少有物种对乙酸盐具有相对抗性。特别是在工业环境中出现的所谓乙酸细菌对高浓度乙酸盐的抗性必须不断地进行选择。为了研究这种高抗性的本质，我们在近中性pH值下，用不断增加乙酸盐浓度的长期连续培养法培养了中度耐乙酸的醋化醋杆菌野生型菌株和对乙酸敏感的大肠杆菌。虽然大肠杆菌在经过125代选择后没有获得任何显著的抗性，但醋化醋杆菌在240代内进化出了在乙酸盐浓度超过50 g/L时生长的能力。在没有选择压力的情况下，这种表型在几代中都是稳定的，因此一定是由基因决定的。与野生型醋化醋杆菌和大肠杆菌相比，进化后的醋化醋杆菌细胞内乙酸盐浓度显著降低，这表明细胞质阴离子积累是乙酸盐毒性的一个重要组成部分。
