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首页> 外文期刊>Journal of bacteriology >Saccharomyces cerevisiae does not accumulate ethanol against a concentration gradient.
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Saccharomyces cerevisiae does not accumulate ethanol against a concentration gradient.

机译：酿酒酵母不会针对浓度梯度积聚乙醇。

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It has been reported that yeast cells accumulate ethanol against a concentration gradient. We initiated a study of the mechanism involved in this phenomenon. However, we found that this accumulation does not occur and that ethanol permeates the yeast cell plasma membrane by simple diffusion. The following evidence supports this conclusion. (i) Uptake and outflow of ethanol in yeast cells followed first-order kinetics and were insensitive to the presence of structural analogs of ethanol, to drastic pH changes, and to the action of reagents of amino and thiol groups. These results strongly suggest that ethanol permeates the yeast cell plasma membrane without involvement of any carrier. (ii) The outflow rate of ethanol seems greater than the ability of this organism to produce ethanol, indicating that intracellular accumulation of ethanol is not possible. (iii) The intracellular concentration of ethanol found was similar to the concentration in culture media in all tested conditions. With the available information, it is difficult to ascertain the reasons for the discrepancy between our results and those previously reported by other authors. However, the inadequacy of the cell-sampling procedure and of the chromatographic conditions used by those authors suggests that the discrepancy may be due to artifacts in the measurements of ethanol.
机译：据报道，酵母细胞针对浓度梯度积累乙醇。我们开始研究这种现象的发生机理。但是，我们发现这种积累不会发生，并且乙醇通过简单的扩散渗透到酵母细胞的质膜中。以下证据支持这一结论。 （i）酵母细胞中乙醇的吸收和流出遵循一级动力学，并且对乙醇的结构类似物的存在，pH的剧烈变化以及氨基和硫醇基试剂的作用不敏感。这些结果强烈表明乙醇在没有任何载体参与的情况下渗透酵母细胞质膜。 （ii）乙醇的流出速率似乎大于该生物体生产乙醇的能力，这表明不可能在细胞内积累乙醇。 （iii）在所有测试条件下，发现的细胞内乙醇浓度类似于培养基中的浓度。利用现有的信息，很难确定我们的结果与先前其他作者所报告的结果之间存在差异的原因。但是，这些作者所使用的细胞采样程序和色谱条件均不足，这表明差异可能是由于乙醇测量中的伪影所致。

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