Physiological characterization of glucose repression in the strains with SNF1 and SNF4 genes deleted

We investigated the effect of Snf1 kinase and its regulatory subunit Snf4 on the regulation of glucose and galactose metabolism in the yeast Saccharomyces cerevisiae by physiologically characterizing Δsnf1, Δsnf4 and Δsnf1Δsnf4 in CEN.PK background in glucose and glucose–galactose-mixture batch cultivations. The main result of this study showed that delayed induction of galactose catabolism was SNF1 or SNF4 gene deletion specific. In comparison to the reference strain, growth delay on galactose was found to last 2.4 times (7 h), 3.1 times (10.5 h) and 9.6 times (43 h) longer for the Δsnf4, Δsnf1 and Δsnf1Δsnf4 strains, respectively. The maximum specific growth rates on galactose were determined to be two to three times lower for the recombinant strains compared to the reference strain (0.13 h−1) and were found to be 0.07, 0.08 and 0.04 h−1 for the Δsnf1, Δsnf4 and Δsnf1Δsnf4 strains, respectively. The study showed that Snf1 kinase was not solely responsible for the derepression of galactose metabolism.