Department of Biotechnology, Engineering College of Lorena, University of São Paulo, Estrada Municipal do Campinho s/n, 12602-810, Lorena, SP, Brazil.
J Ind Microbiol Biotechnol. 2011 Jan;38(1):71-8. doi: 10.1007/s10295-010-0830-6. Epub 2010 Sep 5.
The inhibitory action of acetic acid, ferulic acid, and syringaldehyde on metabolism of Candida guilliermondii yeast during xylose to xylitol bioconversion was evaluated. Assays were performed in buffered and nonbuffered semidefined medium containing xylose as main sugar (80.0 g/l), supplemented or not with acetic acid (0.8-2.6 g/l), ferulic acid (0.2-0.6 g/l), and/or syringaldehyde (0.3-0.8 g/l), according to a 2(3) full factorial design. Since only individual effects of the variables were observed, assays were performed in a next step in semidefined medium containing different concentrations of each toxic compound individually, for better understanding of their maximum concentration that can be present in the fermentation medium without affecting yeast metabolism. It was concluded that acetic acid, ferulic acid, and syringaldehyde are compounds that may affect Candida guilliermondii metabolism (mainly cell growth) during bioconversion of xylose to xylitol. Such results are of interest and reveal that complete removal of toxic compounds from the fermentation medium is not necessary to obtain efficient conversion of xylose to xylitol by Candida guilliermondii. Fermentation in buffered medium was also considered as an alternative to overcome the inhibition caused by these toxic compounds, mainly by acetic acid.
评估了乙酸、阿魏酸和丁香醛对木糖到木糖醇生物转化过程中毕赤酵母代谢的抑制作用。在含有木糖（80.0g/L）作为主要糖的缓冲和非缓冲半限定培养基中进行了测定，根据 2(3)完全析因设计，培养基中添加或不添加乙酸（0.8-2.6g/L）、阿魏酸（0.2-0.6g/L）和/或丁香醛（0.3-0.8g/L）。由于仅观察到变量的单独影响，因此在下一步的半限定培养基中进行了测定，其中单独含有不同浓度的每种有毒化合物，以便更好地了解它们在不影响酵母代谢的情况下可存在于发酵培养基中的最大浓度。结果表明，乙酸、阿魏酸和丁香醛是可能影响毕赤酵母代谢（主要是细胞生长）的化合物，在木糖到木糖醇的生物转化过程中。这些结果很有趣，表明不需要从发酵培养基中完全去除有毒化合物即可获得毕赤酵母对木糖到木糖醇的有效转化。缓冲介质中的发酵也被认为是克服这些有毒化合物（主要是乙酸）引起的抑制的一种替代方法。
