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

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.

Key words:Saccharomyces cerevisiae, Xylose utilization, Genetic background of the host strains, Chromosome integration