Metabolic Engineering of Four GATA Factors to Reduce Urea and Ethyl Carbamate Formation in a Model Rice Wine System

Urea is the most important precursor of ethyl carbamate (EC), a harmful carcinogenic product, in fermented wines. In this study, the effects of four GATA transcriptional factors (Gln3p, Gat1p, Dal80p ,and Gzf3p) on extracellular urea and EC formation and transcriptional changes in urea degradation related genes (DUR1,2 and DUR3) were examined. Compared to the WT strain, the Delta gzf3 mutant showed 18.7% urea reduction and exhibited synergistic effects with over-expressed Gln3p(1-653) and Gat1p(1-375) on extracellular urea reduction. Moreover, Delta gzf3+Gln3p(1-653) and Delta gzf3+Gat1p(1-375) showed significant 38.7% and 43.7% decreases in urea concentration and 41.7% and 48.5% decreases in EC concentration, respectively, in a model rice wine system. These results provide a promising way to reduce urea and EC formation during wine fermentation and raise some cues for the regulations of the four GATA transcriptional factors on the expression of individual nitrogen catabolite repression sensitive genes and their related metabolism pathway.