Transcriptomic and metabolomic analysis reveals genes related to stress tolerance in high gravity brewing.

The fermentation performance of yeast is the key of beer production. High gravity brewing is a commonly used technique in industrial lager beer production and it is environmentally friendly. Therefore, there has been extensive effort toward improving high gravity brewing. In this study, through transcriptomic and metabolomic analysis of two homologous lager yeasts, genes that relate to stress tolerance in high gravity brewing were screened. The results showed EMP pathway and multiple amino acid metabolism pathway were the most enriched pathways, and pyruvate might be the core metabolite. Overexpression and knockdown strains were constructed to verify the genes' functions. The overexpression of MAN2, PCL1 and PFK26 genes were beneficial to fermentation without significantly changes in flavor profiles. The relative intracellular ATP levels can help us understand the change of metabolic flux such as enhancement of sugar consumption. This work is helpful to reveal the stress tolerance mechanism of high gravity brewing and breed yeast strains with improved performance.