Ibeas J I, Jimenez J
Departamento de Genetica, Facultad de Ciencias, Universidad de Malaga, Spain.
Appl Environ Microbiol. 1997 Jan;63(1):7-12. doi: 10.1128/aem.63.1.7-12.1997.
Saccharomyces flor yeasts proliferate at the surface of sherry wine, which contains over 15% (vol) ethanol. Since ethanol is a powerful inducer of respiration-deficient mutants, this alcohol has been proposed to be the source of the high diversity found in the mitochondrial genomes of flor yeasts and other wine yeasts. Southern blot analysis suggests that mitochondrial DNA (mtDNA) polymorphic changes are due to minor lesions in the mitochondrial genome. As determined in this work by pulsed-field gel electrophoresis, restriction analysis, and Southern blot analysis, ethanol-induced petite mutants completely lack mtDNA (rho zero). Ethanol-induced changes in the mitochondrial genome that could explain the observed mtDNA polymorphism in flor yeasts were not found. The transfer of two different mtDNA variants from flor yeasts to a laboratory strain conferred in both cases an increase in ethanol tolerance in the recipient strain, suggesting that mtDNAs are probably subjected to positive selection pressure concerning their ability to confer ethanol tolerance.
弗洛酵母（Saccharomyces flor）在雪利酒表面增殖，雪利酒含有超过15%（体积）的乙醇。由于乙醇是呼吸缺陷型突变体的强大诱导剂，因此有人提出这种酒精是弗洛酵母和其他葡萄酒酵母线粒体基因组中高多样性的来源。Southern印迹分析表明，线粒体DNA（mtDNA）多态性变化是由于线粒体基因组中的微小损伤所致。如本研究通过脉冲场凝胶电泳、限制性分析和Southern印迹分析所确定的，乙醇诱导的小菌落突变体完全缺乏mtDNA（rho零）。未发现乙醇诱导的线粒体基因组变化能够解释弗洛酵母中观察到的mtDNA多态性。将弗洛酵母的两种不同mtDNA变体转移到实验室菌株中，在两种情况下均使受体菌株的乙醇耐受性增加，这表明mtDNA可能因其赋予乙醇耐受性的能力而受到正选择压力。
