Lairón-Peris M, Routledge S J, Linney J A, Alonso-Del-Real J, Spickett C M, Pitt A R, Guillamón J M, Barrio E, Goddard A D, Querol A
Food Biotechnology Department, Institute of Agrochemistry and Food Technology, CSIC, Valencia, Spain.
College of Health and Life Sciences, Aston University, Birmingham, United Kingdom.
Appl Environ Microbiol. 2021 May 26;87(12):e0044021. doi: 10.1128/AEM.00440-21.
Saccharomyces cerevisiae is an important unicellular yeast species within the biotechnological and the food and beverage industries. A significant application of this species is the production of ethanol, where concentrations are limited by cellular toxicity, often at the level of the cell membrane. Here, we characterize 61 S. cerevisiae strains for ethanol tolerance and further analyze five representatives with various ethanol tolerances. The most tolerant strain, AJ4, was dominant in coculture at 0 and 10% ethanol. Unexpectedly, although it does not have the highest noninhibitory concentration or MIC, MY29 was the dominant strain in coculture at 6% ethanol, which may be linked to differences in its basal lipidome. Although relatively few lipidomic differences were observed between strains, a significantly higher phosphatidylethanolamine concentration was observed in the least tolerant strain, MY26, at 0 and 6% ethanol compared to the other strains that became more similar at 10%, indicating potential involvement of this lipid with ethanol sensitivity. Our findings reveal that AJ4 is best able to adapt its membrane to become more fluid in the presence of ethanol and that lipid extracts from AJ4 also form the most permeable membranes. Furthermore, MY26 is least able to modulate fluidity in response to ethanol, and membranes formed from extracted lipids are least leaky at physiological ethanol concentrations. Overall, these results reveal a potential mechanism of ethanol tolerance and suggest a limited set of membrane compositions that diverse yeast species use to achieve this. Many microbial processes are not implemented at the industrial level because the product yield is poorer and more expensive than can be achieved by chemical synthesis. It is well established that microbes show stress responses during bioprocessing, and one reason for poor product output from cell factories is production conditions that are ultimately toxic to the cells. During fermentative processes, yeast cells encounter culture media with a high sugar content, which is later transformed into high ethanol concentrations. Thus, ethanol toxicity is one of the major stresses in traditional and more recent biotechnological processes. We have performed a multilayer phenotypic and lipidomic characterization of a large number of industrial and environmental strains of to identify key resistant and nonresistant isolates for future applications.
酿酒酵母是生物技术以及食品和饮料行业中一种重要的单细胞酵母物种。该物种的一个重要应用是乙醇生产，然而乙醇浓度会受到细胞毒性的限制，这种毒性通常作用于细胞膜水平。在此，我们对61株酿酒酵母菌株的乙醇耐受性进行了表征，并进一步分析了五株具有不同乙醇耐受性的代表性菌株。耐受性最强的菌株AJ4在0%和10%乙醇浓度的共培养中占主导地位。出乎意料的是，尽管MY29没有最高的非抑制浓度或最低抑菌浓度，但它在6%乙醇浓度的共培养中却是优势菌株，这可能与其基础脂质组的差异有关。尽管在菌株之间观察到的脂质组差异相对较少，但在0%和6%乙醇浓度下，耐受性最差的菌株MY26中磷脂酰乙醇胺的浓度明显高于其他菌株，而在10%乙醇浓度下其他菌株之间的磷脂酰乙醇胺浓度变得更为相似，这表明这种脂质可能与乙醇敏感性有关。我们的研究结果表明，AJ4在乙醇存在的情况下最能够使细胞膜适应并变得更具流动性，并且AJ4的脂质提取物也能形成渗透性最强的膜。此外，MY26在响应乙醇时最不能调节膜的流动性，并且由提取的脂质形成的膜在生理乙醇浓度下泄漏最少。总体而言，这些结果揭示了乙醇耐受性的潜在机制，并表明不同酵母物种用于实现这一机制的膜组成有限。许多微生物过程未在工业层面实施，因为与化学合成相比，其产品产量较低且成本更高。众所周知，微生物在生物加工过程中会表现出应激反应，而细胞工厂产品产量不佳的一个原因是生产条件最终对细胞有毒性。在发酵过程中，酵母细胞会遇到高糖含量的培养基，随后培养基会转化为高乙醇浓度。因此，乙醇毒性是传统及现代生物技术过程中的主要应激因素之一。我们对大量工业和环境菌株进行了多层表型和脂质组学表征，以鉴定未来应用中的关键抗性和非抗性分离株。
