Abstract
Auxotrophic marker genes have widely used for genetic engineering in
yeast. However, the effects of auxotrophic strains that are deficient in
synthesis of amino acids or nucleotides on the growth and production are
rarely reported. In this study, a total of eight auxotrophic strains
with single knockout of selective markers were obtained to evaluate cell
growth and free fatty acid (FFA) production in Saccharomyces cerevisiae
with supplementing different concentrations of amino acids or
nucleotides. Generally, except for gene ADE2, most auxotrophic strains
possessed decreased cell growth and FFA production, which could be
remedied by the higher concentrations of supplements. leu2Δ damaged both
growth and production even with supplementation of 1000 mg/L leucine.
Therefore, this study shows that auxotrophs compromise the metabolic
engineering endeavor and provides a guidance in supplementing amino
acids or nucleotides during fermentations for maximizing
bio-productions.