We sought to investigate how far the growth of Saccharomyces cerevisiae under full anaerobiosis is dependent on the widely used anaerobic growth factors (AGF) ergosterol and oleic acid. A continuous cultivation setup was employed and, even forcing ultrapure N2 gas through an O2 trap upstream of the bioreactor, neither cells from S. cerevisiae CEN.PK113-7D (a lab strain) nor from PE-2 (an industrial strain) washed out after an aerobic-to-anaerobic switch in the absence of AGF. S. cerevisiae PE-2 seemed to cope better than the laboratory strain with this extremely low O2 availability, since it presented higher biomass yield, lower specific rates of glucose consumption and CO2 formation, and higher survival at low pH. Lipid (fatty acid and sterol) composition dramatically altered when cells were grown anaerobically without AGF: saturated fatty acid, squalene and lanosterol contents increased, when compared to either cells grown aerobically or anaerobically with AGF. We concluded that these lipid alterations negatively affect cell viability during exposure to low pH or high ethanol titers.

中文翻译：

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永远喘气和永远成长：在没有麦角固醇和不饱和脂肪酸的情况下，酿酒酵母在极低的氧气利用率下的生理状况。

我们试图研究在完全厌氧条件下酿酒酵母的生长取决于广泛使用的厌氧生长因子（AGF）麦角固醇和油酸的程度。采用连续培养设置，甚至迫使超纯氮气通过生物反应器上游的O2捕集阱，啤酒酵母CEN.PK113-7D（实验室菌株）和PE-2（工业菌株）的细胞均未洗出。在没有AGF的情况下从好氧转换为厌氧之后。啤酒酵母PE-2似乎比实验室菌株具有更好的O2利用率，因为它呈现出更高的生物量产量，更低的葡萄糖消耗率和CO2形成率以及在低pH下的更高存活率。当细胞在无AGF的条件下厌氧生长时，脂质（脂肪酸和固醇）的组成发生了巨大变化：饱和脂肪酸，与需氧或需氧厌氧培养的细胞相比，角鲨烯和羊毛甾醇含量增加。我们得出的结论是，这些脂质变化在暴露于低pH或高乙醇滴度时会对细胞活力产生负面影响。