CSIR-Institute of Microbial Technology, Sector-39A, Chandigarh 160036, India.
CSIR-Institute of Microbial Technology, Sector-39A, Chandigarh 160036, India.
Bioresour Technol. 2013 Nov;147:449-455. doi: 10.1016/j.biortech.2013.08.065. Epub 2013 Aug 20.
Debaryomyces hansenii is one of the most promising natural xylitol producers. As the conversion of xylitol to xylulose mediated by NAD(+) cofactor dependent xylitol dehydrogenase (XDH) reduces its xylitol yield, xylitol dehydrogenase gene (DhXDH)-disrupted mutant of D. hansenii having potential for xylose assimilating pathway stopping at xylitol, was used to study the effects of co-substrates, xylose and oxygen availability on xylitol production. Compared to low cell growth and xylitol production in cultivation medium containing xylose as the only substrate, XDH disrupted mutants grown on glycerol as co-substrate accumulated 2.5-fold increased xylitol concentration over those cells grown on glucose as co-substrate. The oxygen availability, in terms of volumetric oxygen transfer coefficient, kLa (23.86-87.96 h(-1)), affected both xylitol productivity and yield, though the effect is more pronounced on the former. The addition of extra xylose at different phases of xylitol fermentation did not enhance xylitol productivity under experimental conditions.
德巴利酵母汉逊氏是最有前途的天然木糖醇生产菌之一。由于依赖 NAD(+)辅因子的木糖醇脱氢酶（XDH）介导的木糖醇向木酮糖的转化会降低木糖醇的产量，因此使用木糖醇脱氢酶基因（DhXDH）缺失突变株德巴利酵母汉逊氏来研究共底物、木糖和氧气供应对木糖醇生产的影响。与仅含有木糖作为唯一底物的培养介质中细胞生长和木糖醇产量低相比，以甘油作为共底物的 XDH 缺失突变株积累的木糖醇浓度比以葡萄糖作为共底物的细胞高 2.5 倍。以体积氧传递系数 kLa（23.86-87.96 h(-1)) 表示的氧气供应，影响木糖醇的生产力和产率，尽管对前者的影响更为显著。在实验条件下，在木糖醇发酵的不同阶段添加额外的木糖并没有提高木糖醇的生产力。
