东方伊萨酵母降解木糖醇发酵抑制物研究

Biodegradation of Xylitol Fermentation Inhibitors by Issatchenkia orientalis

关键词:  东方伊萨酵母  发酵  生物降解  抑制物  木糖醇

Key words:  Issatchenkia orientalis  fermentation  biodegradation  inhibitor  xylitol

摘要:

选择存在于半纤维素水解物中6种主要微生物代谢抑制物,用HPLC-DAD建立检测方法,分析东方伊萨酵母对这些抑制物的降解活性、代谢途径,以及生物脱毒处理对热带假丝酵母木糖醇发酵性能的影响。结果表明,东方伊萨酵母能直接利用醋酸,将芳香醛还原为相应的醇,含有裂解芳香环,最终将其彻底降解的复杂酶系。东方伊萨酵母对抑制物:醋酸4000 m g·L^-1、糠醛400 m g·L^-1、香草醛90 m g·L^-1、对羟基苯甲酸40 m g·L^-1、阿魏酸100 m g·L^-1和愈创木酚30 m g·L^-1脱毒发酵80h的降解率分别为100%,100%,100%,14.3%、65.8%、78.6%,木糖醇发酵性能得到显著改善。经生物脱毒处理之后的醋酸、糠醛、愈创木酚、阿魏酸培养基,再用热带假丝酵母进行木糖醇发酵的产物生成速率(木糖醇g·L^-1.h^-1)分别为2.67,2.66,2.72,2.66,基本达到了商品木糖培养基的木糖醇生成速率水平(2.79)。

Abstract:

An analytic method of HPLC-DAD for determining six main inhibitors in hemicellulose hydrolysate for microbial metabolism was established. Using this method, we analyzed the degradation activities and metabolic pathway of Issatchenkia orientalis utilizing these inhibitors, and measured the effect of biological detoxification on xylitol fermentation ability by Candida tropicalis. The results showed that Issatchenkia orientalis could directly utilize acetic acid, reduce aromatic aldehydes to its corresponding alcohol, and have a series of enzymes cleaving aromatic ring, and entirely degrading aromatic compounds eventually. After biological detoxification by Issatchenkia orientalis fermentation for 80h, the biodegrading percentages of the six inhibitors in each medium were 100, 100, 100, 14.3, 65.8 and 78.6 on each initial concentration (m g·L^-1) of acetic acid at 4000, furfural 400, vanillin 90, hydroxybenzoic acid 40, guaiacol 30, ferulic acid 100, respectively, the fermentation ability of these media were effectively improved. Among these inhibitor media treated by Issatchenkia orientalis, the productivity (xylitol g·L^-1·h^-1) of acetic acid, furfural, guaiacol, ferulic acid media was 2.67, 2.66, 2.72, 2.66, respectively, in xylitol fermentation by Candida tropicalis, and almost reach the same productivity (xylitol 2.79 g·L^-1·h^-1) of commercial xylose medium.