不同食品酵母对葡萄糖的流加强度和热激压力的生理响应

微生物在发酵过程中往往会面临一系列诸如高温、高渗透压、乙醇等压力。该研究探究了4种食品酵母对葡萄糖的流加强度和热激压力的生理响应差异性。结果表明,Pichia kudriavzevii和Saccharomyces cerevisiae的生长几乎没有受到升温压力的影响。高速流加的葡萄糖和梯度升温抑制了Cyberlindnera fabianii的还原糖消耗,而对其他酵母没有影响。P.kudriavzevii和S.cerevisiae的胞内海藻糖表现为对葡萄糖的流加和低压力热激(35、37℃)高度敏感,C.fabianii的胞内海藻糖均表现出低敏感性,而Candida tropicalis的胞内海藻糖仅在严重压力下(>39℃)才开始积累。在所有酵母中,P.kudriavzevii的海藻糖含量在发酵调控后变化最显著,增长了3.7倍。此外,除C.fabianii外,高速流加的葡萄糖有利于P.kudriavzevii、S.cerevisiae和C.tropicalis乙醇的积累,特别是P.kudriavzevii的乙醇含量最高,达到48 g/L。该研究结果可以用于高耐受性菌株的筛选,为生物乙醇和酿造食品的应用提供指导。

Physiological responses of different food yeasts to glucose feeding strength and heating stress

Yeast cells often face a series of stress during the fermentation process,such as high temperature,high osmotic stress and ethanol.This work investigated the physiological responses of four food yeasts to glucose feeding strength and gradient heating stress.The results showed that the growth of Pichia kudriavzevii and Saccharomyces cerevisiae were hardly affected by gradient heating stress.High-speed feeding of glucose(400 mL/h)and gradient heating inhibited the reducing sugar consumption of Cyberlindner fabianii,but had no effect on other yeasts.The trehalose accumulation of P.kudriavzevii and S.cerevisiae were highly sensitive to glucose feeding and low stress heating(35,37℃),C.fabianii showed low sensitivity to both glucose feeding and gradient heating stress,while Candida tropicalis intracellular trehalose only began to accumulate under severe heating stress(above 39℃).The trehalose content of P.kudriavzevii increased most significantly(3.7 times)after fermentation regulation among all yeasts.Meanwhile,other than C.fabianii,high-speed feeding of glucose was beneficial to ethanol accumulation in P.kudriavzevii,S.cerevisiae and C.tropicalis,especially P.kudriavzevii,which had the highest ethanol content of 48 g/L.These results could guide the selection of high tolerance strains and the application of bioethanol and fermented food.