Spencer Jennifer, Phister Trevor G, Smart Katherine A, Greetham Darren
School of Biosciences, University of Nottingham, Loughborough, Leics LE12 5RD, UK.
BMC Res Notes. 2014 Mar 17;7:151. doi: 10.1186/1756-0500-7-151.
Bioethanol fermentations follow traditional beverage fermentations where the yeast is exposed to adverse conditions such as oxidative stress. Lignocellulosic bioethanol fermentations involve the conversion of pentose and hexose sugars into ethanol. Environmental stress conditions such as osmotic stress and ethanol stress may affect the fermentation performance; however, oxidative stress as a consequence of metabolic output can also occur. However, the effect of oxidative stress on yeast with pentose utilising capabilities has yet to be investigated.
Assaying for the effect of hydrogen peroxide-induced oxidative stress on Candida, Pichia and Scheffersomyces spp. has demonstrated that these yeast tolerate hydrogen peroxide-induced oxidative stress in a manner consistent with that demonstrated by Saccharomyces cerevisiae. Pichia guillermondii appears to be more tolerant to hydrogen peroxide-induced oxidative stress when compared to Candida shehatae, Candida succiphila or Scheffersomyces stipitis.
Sensitivity to hydrogen peroxide-induced oxidative stress increased in the presence of minimal media; however, addition of amino acids and nucleobases was observed to increase tolerance. In particular adenine increased tolerance and methionine reduced tolerance to hydrogen peroxide-induced oxidative stress.
生物乙醇发酵遵循传统的饮料发酵方式，在此过程中酵母会面临诸如氧化应激等不利条件。木质纤维素生物乙醇发酵涉及将戊糖和己糖转化为乙醇。环境应激条件，如渗透应激和乙醇应激，可能会影响发酵性能；然而，作为代谢产物的氧化应激也可能发生。然而，氧化应激对具有戊糖利用能力的酵母的影响尚未得到研究。
检测过氧化氢诱导的氧化应激对念珠菌属、毕赤酵母属和休哈塔假丝酵母属的影响，结果表明这些酵母耐受过氧化氢诱导的氧化应激的方式与酿酒酵母一致。与嗜杀假丝酵母、嗜糖假丝酵母或树干毕赤酵母相比，季也蒙毕赤酵母似乎对过氧化氢诱导的氧化应激更具耐受性。
在基本培养基存在的情况下，对过氧化氢诱导的氧化应激的敏感性增加；然而，观察到添加氨基酸和核苷碱基可提高耐受性。特别是腺嘌呤提高了耐受性，而甲硫氨酸降低了对过氧化氢诱导的氧化应激的耐受性。
