Sterols are essential components of the yeast membrane and their synthesis requires oxygen. Yet, Saccharomyces cerevisiae has developed the ability to take up sterols from the medium under anaerobiosis. Here we investigated sterol uptake efficiency and the expression of genes related to sterol import in Saccharomyces and non-Saccharomyces wine yeast species fermenting under anaerobic conditions. The sterol uptake efficiency of 39 strains was evaluated by flow cytometry (with 25-NBD Cholesterol, a fluorescent cholesterol probe introduced in the medium) and we found an important discrepancy between Saccharomyces and non-Saccharomyces wine yeast species that we correlated to a lower final cell population and a lower fermentation rate. A high uptake of sterol was observed in the various Saccharomyces strains. Spot tests performed on 13 of these strains confirmed the differences between Saccharomyces and non-Saccharomyces strains, suggesting that the presence of the sterol uptake transporters AUS1 and PDR11 could cause these discrepancies. Indeed, we could not find any homologue to these genes in the genome of Hanseniaspora uvarum, H. guillermondii, Lachancea thermotolerans, Torulaspora delbreueckii, Metschnikowia pulcherrima, or Starmarella bacillaris species. The specialization of sterol import function for post genome-duplication species may have favored growth under anaerobiosis.

中文翻译：

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酵母菌和非酵母菌葡萄酒酵母菌种的甾醇摄取分析

甾醇是酵母膜的重要组成部分，它们的合成需要氧气。然而，酿酒酵母已经发展出在厌氧条件下从培养基中吸收甾醇的能力。在这里，我们研究了在厌氧条件下发酵的酵母菌和非酵母菌葡萄酒酵母物种中甾醇的摄取效率和与甾醇输入相关的基因的表达。通过流式细胞术（使用 25-NBD 胆固醇，一种在培养基中引入的荧光胆固醇探针）评估 39 株菌株的甾醇摄取效率，我们发现酵母菌和非酵母菌葡萄酒酵母物种之间存在重要差异，我们将其与较低的最终结果相关联细胞群和较低的发酵速率。在各种酵母菌菌株中观察到甾醇的高摄取。对这些菌株中的 13 种进行的现场测试证实了酵母属和非酵母属菌株之间的差异，这表明甾醇摄取转运蛋白 AUS1 和 PDR11 的存在可能导致这些差异。事实上，我们在 Hanseniaspora uvarum、H. guillermondii、Lachancea thermotolerans、Torulaspora delbreueckii、Metschnikowia pulcherrima 或 Starmarella bacillaris 物种的基因组中找不到与这些基因的任何同源物。基因组复制后物种的甾醇输入功能的专门化可能有利于厌氧条件下的生长。我们在 Hanseniaspora uvarum、H. guillermondii、Lachancea thermotolerans、Torulaspora delbreueckii、Metschnikowia pulcherrima 或 Starmarella bacillaris 物种的基因组中找不到与这些基因的任何同源物。基因组复制后物种的甾醇输入功能的专门化可能有利于厌氧条件下的生长。我们在 Hanseniaspora uvarum、H. guillermondii、Lachancea thermotolerans、Torulaspora delbreueckii、Metschnikowia pulcherrima 或 Starmarella bacillaris 物种的基因组中找不到与这些基因的任何同源物。基因组复制后物种的甾醇输入功能的专门化可能有利于厌氧条件下的生长。