FIG 6.

The concentrations of nine yeast-derived aroma compounds in the beers fermented with the variant strains relative to those fermented with the wild-type strains Y1 (A), Y2 (B), Y3 (C), and Y4 (D). Values are means from two independent fermentations, and asterisks depict a significant difference in the variant compared to the wild-type, as determined by two-tailed Student's t test (*, P < 0.05; **, P < 0.01; ***, P < 0.001). The black lines depict the concentrations produced by the wild-type strains. The compounds are displayed by type: higher alcohols, esters, and vicinal diketones (VDK). The types are colored by whether the compounds are generally considered undesirable (red) or desirable (green) in lager beer (34). Me, methyl.