Genetic determinants for enhanced glycerol growth of Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae generally shows a low natural capability to utilize glycerol as the sole source of carbon, particularly when synthetic medium is used and complex supplements are omitted. Nevertheless, wild type isolates have been identified that show a moderate growth under these conditions. In the current study we made use of intraspecies diversity to identify targets suitable for reverse metabolic engineering of the non-growing laboratory strain CEN.PK113-1A. A genome-wide genetic mapping experiment using pooled-segregant whole-genome sequence analysis was conducted, and one major and several minor genetic loci were identified responsible for the superior glycerol growth phenotype of the previously selected S. cerevisiae strain CBS 6412-13A. Downscaling of the major locus by fine-mapping and reciprocal hemizygosity analysis allowed the parallel identification of two superior alleles (UBR2CBS 6412-13A and SSK1CBS 6412-13A). These alleles together with the previously identified GUT1CBS 6412-13A allele were used to replace the corresponding alleles in the strain CEN.PK113-1A. In this way, glycerol growth could be established reaching a maximum specific growth rate of 0.08h(-1). Further improvement to a maximum specific growth rate of 0.11h(-1) could be achieved by heterologous expression of the glycerol facilitator FPS1 from Cyberlindnera jadinii.