Disruption of GAL1 Gene in Saccharomyces cerevisiae Leads to Higher Ethanol Production

Document Type : Research Paper


1 Faculty of Medical Sciences, Tarbiat Modarres University, Tehran, I.R. Iran,

2 Microbial Metabolic Engineering Research Units, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Taejon, South Korea.


GAL gene family is a set of structural and regulatory genes that enables cells to utilize galactose as a carbon
source in Saccharomyces cerevisiae. Phosphorylation of intracellular galactose can be catalyzed by
galactokinase (encoded by GAL1 gene). In this study role of GAL1 gene on ethanol production by S. cerevisiae
together with physiological characterization of GAL1 mutant strain was studied. Aerobic cultivation was carried out with wild-type strain and the GAL1 mutant. The GAL1 mutant strain displayed fermentative growth in early exponential phase. Deletion of the GAL1 gene was shown to have a major impact on biomass and ethanol formation. The GAL1 mutant exhibited a decrease in growth rate and increased ethanol production. Furthermore the results showed that glucose consumption by GAL1 mutants did not favor biomass formation, rather cause excessive respiro-fermentative metabolism, with whereas could linear increase in ethanol  production.