Departamento de Bioquímica, Instituto de Química, UFRJ, 21941-909, Rio de Janeiro, RJ, Brazil.
Appl Microbiol Biotechnol. 2011 Apr;90(2):697-704. doi: 10.1007/s00253-010-3053-x. Epub 2011 Jan 18.
The fermentation process offers a wide variety of stressors for yeast, such as temperature, aging, and ethanol. To evaluate a possible beneficial effect of trehalose on ethanol production, we used mutant strains of Saccharomyces cerevisiae possessing different deficiencies in the metabolism of this disaccharide: in synthesis, tps1; in transport, agt1; and in degradation, ath1 and nth1. According to our results, the tps1 mutant, the only strain tested unable to synthesize trehalose, showed the lowest fermentation yield, indicating that this sugar is important to improve ethanol production. At the end of the first fermentation cycle, only the strains deficient in transport and degradation maintained a significant level of the initial trehalose. The agt1, ath1, and nth1 strains showed the highest survival rates and the highest proportions of non-petites. Accumulation of petites during fermentation has been correlated to low ethanol production. When recycled back for a subsequent fermentation, those mutant strains produced the highest ethanol yields, suggesting that trehalose is required for improving fermentative capacity and longevity of yeasts, as well as their ability to withstand stressful industrial conditions. Finally, according to our results, the mechanism by which trehalose improves ethanol production seems to involve mainly protection against protein oxidation.
发酵过程为酵母提供了各种各样的应激因素，如温度、老化和乙醇。为了评估海藻糖对乙醇生产的可能有益影响，我们使用了具有不同二糖代谢缺陷的酿酒酵母突变株：在合成中，tps1；在运输中，agt1；在降解中，ath1 和 nth1。根据我们的结果，tps1 突变株，即唯一不能合成海藻糖的测试菌株，表现出最低的发酵产率，表明这种糖对提高乙醇生产很重要。在第一个发酵周期结束时，只有缺乏运输和降解的菌株保持了初始海藻糖的显著水平。agt1、ath1 和 nth1 菌株表现出最高的存活率和最高比例的非小菌落。发酵过程中小菌落的积累与低乙醇产量有关。当这些突变株被回收用于后续发酵时，它们产生了最高的乙醇产量，这表明海藻糖对于提高酵母的发酵能力和寿命以及它们耐受工业压力条件的能力是必需的。最后，根据我们的结果，海藻糖提高乙醇产量的机制似乎主要涉及对蛋白质氧化的保护。
