Influence of individual HXT transporters in xylose fermentation by recombinant Saccharomyces cerevisiae strains

Davi Ludvig Gonçalves,Margareth Patiño Lagos,Boris Stambuk,Akinori Matsushika,Belisa Bordin De Sales,Tetsuya Goshima

doi:10.1186/1753-6561-8-s4-p209

Abstract

Background Lignocellulosic biomass is an attractive raw material for bioethanol production since it is an abundant and renewable feedstock that does not compete with food and feed production [1]. Xylose is the most abundant pentose present on these feedstocks, and although S. cerevisiae cannot readily ferment this sugar, the overexpression of the genes for xylose reductase (XR) and xylitol dehidrogenase (XDH) from P. stiptis and xylulokinase (XK) from S. cerevisiae allows the utilization of xylose [2]. However S. cerevisiae also lacks specific transporters for this sugar and thus the uptake of xylose is carried out by native hexose transporters encoded by the HXT1-HXT7 genes [3]. In the present report we analyzed the impact of individual HXT transporters on xylose fermentation by recombinant S. cerevisiae yeast strains overexpressing the genes for XR, XDH and XK [4].

Highlights

Lignocellulosic biomass is an attractive raw material for bioethanol production since it is an abundant and renewable feedstock that does not compete with food and feed production [1]
Cultivations were perfomed in rich (YP) or synthetic complete (SC) medium containing the required sugars and when necessary, 2% Bacto agar, 0.5 mg/l aureobasidin A and 200 mg/l Geneticin were added to the medium
The deletion of individual HXT genes had no detectable effect on glucose fermentations, but these knockout strains ferment xylose poorly, even under glucose plus xylose conditions

Summary

Introduction

Lignocellulosic biomass is an attractive raw material for bioethanol production since it is an abundant and renewable feedstock that does not compete with food and feed production [1]. Methods Cultivations were perfomed in rich (YP) or synthetic complete (SC) medium containing the required sugars and when necessary, 2% Bacto agar, 0.5 mg/l aureobasidin A and 200 mg/l Geneticin were added to the medium. The chromosome-integrative plasmid pAURXKXDHXR [4] containing PGK promoters for overexpression of XR, XDH and XK was digested with BsiWI and chromosomally integrated into the AUR1 locus of the yeast strains.

Results

Conclusion