Application of co-cultures of engineered Saccharomyces cerevisiae strains to reduce byproduct formation during anaerobic ethanol fermentation

Glycerol is the major organic byproduct of industrial ethanol production with the yeast Saccharomyces cerevisiae. Improved ethanol yields can be achieved with S. cerevisiae strains in which heterologous pathways replace glycerol formation as major NADH redox-cofactor-balancing mechanism. In one such strategy, introduction of phosphoribulokinase (PRK) and ribulose-1,5-bisphosphate carboxylase (RuBisCO) couples conversion of glucose to ethanol to a net oxidation of NADH. In another, introduction of a heterologous acetylating acetaldehyde dehydrogenase (A-ALD) couples NADH re-oxidation to ethanol production from acetate. The present study explores potential advantages of co-cultivating PRK-RuBisCO-based strain and A-ALD-based strains.