不同宿主来源的重组酿酒酵母混合糖代谢比较

Comparison of glucose/xylose cofermentation in recombinant Saccharomyces cerevisiae strains using different hosts

摘要:

【目的】研究不同工业酿酒酵母宿主背景对重组酵母木糖利用效率的影响。【方法】将木糖利用途径的木糖还原酶(XR)、木糖醇脱氢酶(XDH)和木酮糖激酶(XK)编码基因串联后分别转入3株不同的工业酿酒酵母中，得到重组酵母ZQ1、ZQ5和ZQ7。分别对3个木糖途径代谢基因的表达水平、酶活和重组菌株的木糖发酵效率进行比较。【结果】重组菌株在木糖代谢基因转录、酶活性和木糖利用性能方面有很大差异，其中ZQ5木糖代谢能力最强，ZQ7其次，ZQ1木糖利用能力最弱。ZQ7在初始木糖浓度为20 g/L时木糖利用速率快于ZQ5，表明木糖浓度对重组菌发酵性能评价具有影响。【结论】不同菌株的遗传背景和木糖浓度对重组菌木糖利用的影响很大，评价重组酵母的木糖利用需考虑宿主的遗传背景和底物浓度的影响。

Abstract:

[Objective] This study aims to investigate the influence of different genetic backgrounds of Saccharomyces cerevisiae on xylose utilization of the recombinant yeast strains. [Methods] Three xylose recombinant strains designated as ZQ1, ZQ5 and ZQ7 were constructed by employing xylose reductase (XR), xylitol dehydrogenase (XDH) and xylulose kinase (XK) encoding genes via chromosome integration, and in the meantime, transcription levels of three genes and their corresponding enzyme activities as well as sugar mixture fermentation were also investigated. [Results] Gene expression levels and enzyme activities were significantly different in the three recombinant strains; in addition, xylose utilization capabilities of the three strains also varied. ZQ5 showed the highest ability in both gene expression and fermentation capability, which was followed by ZQ7, whereas ZQ1 showed the poorest xylose utilization efficiency. However, xylose utilization rate of ZQ7 outperformed ZQ5 when initial xylose concentration was 20 g/L. [Conclusion] Genetic background and initial xylose concentration exert control on xylose utilization in the recombinant strains, which should be considered in evaluation of the performance of recombinant strains.