Effect of ‘loss of function’ mutation in <i> SER1 </i> in wine yeast: fermentation outcomes in co-inoculation with non-<i>Saccharomyces </i>

In wine fermentation, improved complexity and sensorial properties can arise from the use of non-Saccharomyces yeast. Generally less alcohol tolerant, such strains often do not finish therefore requiring a second inoculation with more robust Saccharomyces cerevisiae, usually added on Day 3. This sequential approach affords time to make an impact before being overtaken by S. cerevisiae. However, two inoculations are inconvenient; identification slow growing cerevisiae strain that be used in single co-inoculation yeast is highly attractive. this study we investigated naturally occurring ‘loss function’ SER1 variant, identified Sake yeast, for purposes carrying out co-inoculated fermentations. The SER1-232(G > C; G78R) change was introduced into commonly strain, EC1118, via CRISPR/Cas9 editing. chemically defined grape juice medium, SER1(G78R) mutant grew fermented slowly increased acetic acid, succinic acid glycerol concentrations. Simultaneous slower-growing Metschnikowia pulcherrima or Lachancea thermotolerans sterile Sauvignon blanc resulted differences compounds, most likely derived presence yeasts. EC1118 (G78R) completed fermentation M. pulcherrima, MP2, fact viability MP2 compared when it as monoculture. also promoted both growth SO2-sensitive L. Viniflora® Concerto™, high SO2 its subsequent dominance during fermentation. co-fermentations wild-type Concerto™ population substantially reduced no significant changes properties. research adds our understanding novel slow-growing fermentations strains.