Functional and Evolutionary Characterization of Diastatic Brewing Yeast Strains. Saccharomyces cerevisiae

Diastatic strains of Saccharomyces cerevisiae are of particular interest to brewers, yeast distributors, and industrial sectors for their unique ability to release glucose from non-fermentable polysaccharides. While this phenotype can be harnessed to produce distinct beer styles or bioethanol from dextrin-rich substrates, these strains are also considered spoilage risks for brewers. Here, we screened a panel of 96 brewing strains for the presence of STA genes, annotated open reading frame and promoter variants, and measured diastatic functional activity at the strain and allelic levels. Additionally, we compared promoter strengths, induction kinetics, and strain-promoter compatibility between relevant strains. Using high quality genome assemblies derived from combined short (Illumina) and long (Oxford Nanopore) reads, we identified conserved allelic variations, generated phylogenetic trees, and proposed a conceptual model for the evolutionary history of the STA gene family.