State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi Jiangsu 214122, China.
J Biotechnol. 2019 Apr 20;296:7-13. doi: 10.1016/j.jbiotec.2019.01.026. Epub 2019 Mar 7.
Xylitol is a sugar alcohol that is used as a sweetener in food and confections. Industrially, xylitol is manufactured by chemical hydrogenation of d-xylose, which requires expensive separation and purification steps as well as high pressure and temperature. The microbial production of xylitol has been examined as an alternative to the chemical process. In this study, a xylitol over-producing strain is breeded by mutagenesis of a newly isolated yeast Candida tropicalis with a new mutation breeding system named atmospheric and room temperature plasma. The highest yield strain T31 was screened among more than 200 mutants with a xylitol yield of 0.61 g/g, which represents a yield increase of 22%. Furthermore, a two-stage dissolved oxygen supply strategy was used in a fermentation process resulting the maximum xylitol yield 0.79 g/g, which makes it a promising candidate for xylitol production. Further biochemical analysis indicating the relative gene expression and the enzyme activity of xylose reductase were higher in mutants than those in the original strain, which partly explained the high yield of xylitol. Thus, this study provides a new strategy to breed the over-producing strains for the xylitol industry.
木糖醇是一种糖醇，用作食品和糖果中的甜味剂。工业上，木糖醇通过 d-木糖的化学氢化来制造，这需要昂贵的分离和纯化步骤以及高压和高温。微生物生产木糖醇已被视为替代化学过程的一种方法。在这项研究中，通过使用一种名为大气压和室温等离子体的新诱变育种系统对新分离的酵母热带假丝酵母进行诱变，选育出了一种木糖醇高产菌株。在 200 多个突变体中筛选出最高产菌株 T31，其木糖醇产量为 0.61 g/g，产量提高了 22%。此外，在发酵过程中采用了两段式溶解氧供应策略，使木糖醇的最大产量达到 0.79 g/g，这使其成为生产木糖醇的有前途的候选者。进一步的生化分析表明，突变体中木糖还原酶的相对基因表达和酶活性高于原始菌株，这部分解释了木糖醇的高产。因此，本研究为木糖醇工业提供了一种新的选育高产菌株的策略。
