Dong Shi-Jun, Yi Chen-Feng, Li Hao
Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, People's Republic of China.
Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, People's Republic of China.
Int J Biochem Cell Biol. 2015 Dec;69:196-203. doi: 10.1016/j.biocel.2015.10.025. Epub 2015 Oct 26.
During bioethanol fermentation process, Saccharomyces cerevisiae cell membrane might provide main protection to tolerate accumulated ethanol, and S. cerevisiae cells might also remodel their membrane compositions or structure to try to adapt to or tolerate the ethanol stress. However, the exact changes and roles of S. cerevisiae cell membrane components during bioethanol fermentation still remains poorly understood. This study was performed to clarify changes and roles of S. cerevisiae cell membrane components during bioethanol fermentation. Both cell diameter and membrane integrity decreased as fermentation time lasting. Moreover, compared with cells at lag phase, cells at exponential and stationary phases had higher contents of ergosterol and oleic acid (C18:1) but lower levels of hexadecanoic (C16:0) and palmitelaidic (C16:1) acids. Contents of most detected phospholipids presented an increase tendency during fermentation process. Increased contents of oleic acid and phospholipids containing unsaturated fatty acids might indicate enhanced cell membrane fluidity. Compared with cells at lag phase, cells at exponential and stationary phases had higher expressions of ACC1 and HFA1. However, OLE1 expression underwent an evident increase at exponential phase but a decrease at following stationary phase. These results indicated that during bioethanol fermentation process, yeast cells remodeled membrane and more changeable cell membrane contributed to acquiring higher ethanol tolerance of S. cerevisiae cells. These results highlighted our knowledge about relationship between the variation of cell membrane structure and compositions and ethanol tolerance, and would contribute to a better understanding of bioethanol fermentation process and construction of industrial ethanologenic strains with higher ethanol tolerance.
在生物乙醇发酵过程中，酿酒酵母细胞膜可能提供主要保护以耐受积累的乙醇，并且酿酒酵母细胞也可能重塑其膜组成或结构以试图适应或耐受乙醇胁迫。然而，在生物乙醇发酵过程中酿酒酵母细胞膜成分的确切变化和作用仍知之甚少。本研究旨在阐明生物乙醇发酵过程中酿酒酵母细胞膜成分的变化和作用。随着发酵时间的延长，细胞直径和膜完整性均降低。此外，与延滞期的细胞相比，指数期和稳定期的细胞麦角固醇和油酸（C18:1）含量较高，但十六烷酸（C16:0）和棕榈油酸（C16:1）含量较低。在发酵过程中，大多数检测到的磷脂含量呈增加趋势。油酸和含有不饱和脂肪酸的磷脂含量增加可能表明细胞膜流动性增强。与延滞期的细胞相比，指数期和稳定期的细胞ACC1和HFA1表达较高。然而，OLE1表达在指数期明显增加，但在随后的稳定期下降。这些结果表明，在生物乙醇发酵过程中，酵母细胞重塑了膜，更具变化性的细胞膜有助于酿酒酵母细胞获得更高的乙醇耐受性。这些结果突出了我们对细胞膜结构和组成变化与乙醇耐受性之间关系的认识，并将有助于更好地理解生物乙醇发酵过程以及构建具有更高乙醇耐受性的工业产乙醇菌株。
