The High-Capacity Specific Fructose Facilitator ZrFfz1 Is Essential for the Fructophilic Behavior of Zygosaccharomyces rouxii CBS 732T

Abstract

ABSTRACTZygosaccharomyces rouxiiis a fructophilic yeast that consumes fructose preferably to glucose. This behavior seems to be related to sugar uptake. In this study, we constructedZ. rouxiisingle-, double-, and triple-deletion mutants in the UL4 strain background (aura3strain derived from CBS 732T) by deleting the genes encoding the specific fructose facilitatorZ. rouxiiFfz1 (ZrFfz1), the fructose/glucose facilitator ZrFfz2, and/or the fructose symporter ZrFsy1. We analyzed the effects on the growth phenotype, on kinetic parameters of fructose and glucose uptake, and on sugar consumption profiles. No growth phenotype was observed on fructose or glucose upon deletion ofFFZgenes. Deletion of ZrFFZ1drastically reduced fructose transport capacity, increased glucose transport capacity, and eliminated the fructophilic character, while deletion of ZrFFZ2had almost no effect. The strain in which bothFFZgenes were deleted presented even higher consumption of glucose than strain Zrffz1Δ, probably due to a reduced repressing effect of fructose. This study confirms the molecular basis of theZ. rouxiifructophilic character, demonstrating that ZrFfz1 is essential forZ. rouxiifructophilic behavior. The gene is a good candidate to improve the fructose fermentation performance of industrialSaccharomyces cerevisiaestrains.