MIG1 Glucose Repression in Metabolic Processes of Saccharomyces cerevisiae: Genetics to Metabolic Engineering

Abstract

Background: Although Saccharomyces cerevisiae has several industrial applications, there are still fundamental problems associated with sequential use of carbon sources. As such, glucose repression effect can direct metabolism of yeast to preferably anaerobic conditions. This leads to higher ethanol production and less efficient production of recombinant products. The general glucose repression system is constituted by MIG1, TUP1 and SSN6 factors. The role of MIG1 is known in glucose repression but the evaluation of effects on aerobic/anaerobic metabolism by deletion of MIG1 and constructing an optimal strain brand remains unclear and an objective to be explored.

Methods: To find the impact of MIG1 in induction of glucose-repression, the Mig1 disruptant strain (ΔMIG1) was produced for comparing with its congenic wild-type strain (2805). The analysis approached for changes in the rate of glucose consumption, biomass yield, cell protein contents, ethanol and intermediate metabolites production. The MIG1 disruptant strain exhibited 25% glucose utilization, 12% biomass growth rate and 22% protein content over the wild type. The shift to respiratory pathway has been demonstrated by 122.86 and 40% increase of glycerol and pyruvate production, respectively as oxidative metabolites, while the reduction of fermentative metabolites such as acetate 35.48 and ethanol 24%.

Results: Results suggest that ΔMIG1 compared to the wild-type strain can significantly present less effects of glucose repression.

Conclusion: The constructed strain has more efficient growth in aerobic cultivations and it can be a potential host for biotechnological recombinant yields and industrial interests.

Keywords: Homologous recombination; Metabolic pathways; Saccharomyces cerevisiae; Yeasts.

Figure 1.

Amplified N fragment (400 bp) and C fragment (600 bp) of MIG1 chromosomal gene of Saccharomyces Cerevisiae next to the size marker. The size marker (SM) contains of bands for each equals to 100 bp.

Figure 2.

Concentration of A) glucose, B) cell mass, C) ethanol, and D) cell protein in batch cultivations of wild strains 2805(■) and ΔMIG1 (MIG1 disrupted mutant) (▲) on a medium with glucose control conditions. The data achieved of three independent experiences and calculated mean values have been demonstrated for each amount on the related graph, (n=3), p<0.05, significantly different characteristics of mutant strain from respective wild strain.

Figure 3.

Different production ratio (Percent variation Δ%) of metabolite parameter (Acetic acid, Glycerol, Pyruvic acid) in batch cultivations of wild strains 2805 (■) and ΔMIG1(MIG1 disrupted mutant) (■) on a medium with glucose control conditions.