Abstract: In industrial fermentation processes,Saccharomyces cerevisiae is commonly used for ethanol production,but it lacks the ability to ferment pentose sugars like D -xylose.Heterologous expression of a xylose isomerase (XI) would enable yeast cells to metabolize xylose.However,many attempts to express a prokaryotic XI with high activity in S.cerevisiae have failed so far.The present work is on functionally expressing xylose isomerase (XI) of plant origin in Saccharomyces cerevisiae.The Arabidopsis thaliana XI exhibited high specific XI activity (0.51 U/mg protein) in S.cerevisiae.The A. thaliana XI has low sequence similarities (50; -53; ) to the XIs previously functionally expressed in S.cerevisiae.The Km of the A.thaliana XI is 46.08 mM.Importantly,the A.thaliana XI is less inhibited by xylitol ( Ki,13.21mM),a side product during xylose fermentation.This work provides a promising starting point for further improvement of xylose fermentation in yeast strains.

摘要： 酿酒酵母是工业上乙醇发酵的首选目标微生物,但是不能代谢木糖等五碳糖.通过导入外源木糖异构酶基因,可以赋予酵母利用木糖的能力.但是长期的研究发现很难将细菌木糖异构酶转入酿酒酵母得到活性表达.研究成功的在酿酒酵母里表达了拟南芥木糖异构酶,其活性可达到0.51 U/(mg·protein).拟南芥木糖异构酶与成功在酵母里表达的真菌木糖异构酶相比更加耐受木糖醇抑制(Ki=13.21 mM).本研究为改善酵母利用木糖提供了新的可用的木糖异构酶.