Whole-cell gene and protein expression profilings of saccharomyces cerevisiae grown under different gravity environments

二氧化碳（CO2）的失衡一直被认为是全球变暖的主要原因。人们提出了许多减少二氧化碳排放的方法。用乙醇代替部分汽油是一种很有前途的方法。对现有的乙醇生产工艺稍加修改，就可以使用高糖含量的底物。然而，饲喂含糖量高的底物并不能保证乙醇产量高，反而会导致酵母细胞死亡。这种不良结果归因于高糖浓度的渗透作用和高乙醇浓度的抑制作用的综合作用。造成这种不良后果的具体原因尚不清楚。2005年全球乙醇产量接近140亿升。乙醇产量每提高1%就能带来数千万美元的利润。因此，高乙醇产量的生产工艺是受欢迎的。

Imbalance of carbon dioxide (CO2) has been considered as the major cause of global warming. Many approaches to reducing CO2 emission have been proposed. Using ethanol to replace a portion of gasoline is one of the promising approaches. With a slight modification of the existing ethanol production process, using a high sugar-content substrate becomes possible. However, feeding with a high sugar-content substrate does not guarantee high ethanol yield, but would lead to yeast cell death. Such an adverse result is attributed to a combined osmotic effect due to high sugar concentration and inhibitory effect due to high ethanol level. The detailed cause of such an adverse outcome is still unclear. The global ethanol production in 2005 was nearly 14 billion liters. A one-percent increase in ethanol productivity would translate to tens of million of dollars in profit. Thus a high ethanol-yield production process is welcome.