Factors Affecting Sugar Utilization and Rate of Fermentation During Vinification

In this grant year we have: 1) successfully developed the technology for the analysis of HXT gene expression; 2) developed methodology yielding high quantities of high quality mRNA from strains of Saccharomyces during grape juice fermentation; 3) begun profiling of H’XT gene expression during grape juice fermentation conducted by commercial strains; 4) confirmed the critical role of HXT2 in non-proliferative phase fermentation of glucose and fructose in grape juice; 5) defined the pathway by which the HXT2 transporter is degraded in response to nitrogen limitations. Further, we have shown that HXTl and HXT3 are expressed early during the fermentation of grape juice, with a shift to HXT2 and HXT3 upon entry into stationary phase of growth during the fermentation. We are now poised to undertake a more thorough investigation of expression of the remainder of the HXT genes during grape juice fermentation.