Auxotrophs compromise cell growth and fatty acid production in Saccharomyces cerevisiae

Auxotrophic marker genes have been widely used for genetic engineering in yeast. However, the effects of amino acids or nucleotides deficiency in auxotrophic strains on cell growth and product synthesis were rarely reported. In this study, a total of eight auxotrophic strains of Saccharomyces cerevisiae with single knockout of selection markers were obtained. Cell growth and free fatty acid (FFA) production of these auxotrophic strains were evaluated with supplementation of different concentrations of amino acids or nucleotides. Generally, except ade2 Delta mutants, most auxotrophic strains showed decreased cell growth and FFA production, which could be recovered by adding higher concentrations of supplements. LEU2 deletion (leu2 Delta) damaged both cell growth and FFA production even with supplementation of 1000 mg L-1 leucine. This study shows that growth and product biosynthesis of auxotrophs could be limited by insufficient supplementation of amino acids or nucleotides, and provides guidance on supplementation of these nutrients during fermentation to maximize cell growth and product biosynthesis.

Automated summary

This study found that the deficiency of amino acids and nucleotides has effects on cell growth and product synthesis in yeast. These effects can be restored by adding appropriate supplementation of amino acids or nucleotides.