Identification of molecular markers for early detection of slug- 2 gish fermentation associated with heat-shock during alcoholic 3 fermentation

Abstract

Problematic fermentations frequently drive economic losses and logistic problems in the winemaking industry. Previous studies have determined thermal conditions leading to problematic fermentations, selecting two contrasting yeast strains for further transcriptomic analysis. Saccharomyces cerevisiae SBB11 showed strong thermosensitivity towards heat shock, while S. cerevisiae PDM was found to be thermotolerant. The aim of this study was to select genes with significantly upregulated expression to be later used as biomarkers for early detection of sluggish fermentation associated with heat shock. Candidate genes were selected from previously obtained RNA-seq data. Alcoholic fermentations were conducted with 4 S. cerevisiae strains SBB11, PDM, M2 and ICV D21. Heat shocks on day 3 of alcoholic fermentation were applied at 36 and 40 °C for 16 h. S. cerevisiae cells were collected at different times after heat shock onset for qPCR analysis of candidate gene expression over time. Three genes showed promising results; SSA1, MGA1 and OPI10 significantly increased expression with respect to the control. The selected genes showed increased expression during the first 9 h post heat shock and are proposed for early detection of sluggish fermentations associated with heat shock.