Abstract:
In the wine industry, it is standard practice to ferment white and rosé wines at low temperature (10-15ºC). However, low temperatures increase the fermentation duration and the risk of sluggish or stuck ferments, which can lead to significant product and profit loss. The primary objective of this research was to identify Saccharomyces cerevisiae genes, from a prior list of candidates, linked to the duration of the fermentation lag phase at temperatures (15ºC) relevant to white winemaking. Secondly, this work aimed to further explore the genetic basis of the individual candidate genes linked to fermentation lag phase identified during the first objective. This step determined whether the influence on lag phase is temperature-specific by comparing the relative lag at 12.5ºC compared to 25ºC. In this project, the lag phase of 28 S. cerevisiae BY4743 gene deletion strains was screened using fermentations in synthetic grape medium at 15ºC. Gene deletants identified that differed in lag phase duration were selected and these candidate genes were deleted in S288C and RM11-1a. Reciprocal hemizygosity analysis (RHA) was used to confirm the genetic linkage of one of these genes, CGI121, to lag phase. The gene sequence of CGI121 alleles of RM11-1a and S288C were compared to determine whether CGI121 allelic variants could be a target for breeding commercial wine yeast with altered fermentation lag times.