The synergistic effects of ammonium and phosphorus on higher alcohol biosynthesis in Zygosaccharomyces mellis LGL-1 and its application for wampee/grape winemaking.

For wine, higher alcohols are double-edged swords, which benefit flavors in appropriate amount but cause negative effects on aromas as well as side-effects for consumers in excessive amount. In this study, five kinds of ammonium salts were tested to reduce higher alcohols produced by Zygosaccharomyces mellis LGL-1 (LGL-1), among which, (NH4)2HPO4 exhibited most excellent effects with higher alcohols reduced by 32.79 %. Both NH4+ and HPO42- demonstrated individual capacities to reduce higher alcohol levels and transcriptome analysis was employed to investigate the synergistic mechanism. Results showed that both NH4+ and HPO42- could regulate higher alcohol biosynthesis, but with different regulators, Cat8 for the synergistic effect of NH4+ and HPO42-, and Ino80 for HPO42- specifically. Meanwhile, HPO42- reduced the activity of BCAT2, specifically and NH4+ increased the activity of BCAT1 particularly, the combination of which led to the reduction of higher alcohol biosynthesis. Both Gtr1 and TorC1 were downregulated with HPO42- or NH4+ addition, with more pronounced downregulations under their combination. Collectively, the synergistic effects of ammonium and phosphorus on higher alcohol biosynthesis in LGL-1 were existed. To amplify this effect, the molar ratio of nitrogen to phosphorus was optimized and a mole ratio of 1:1 was applied for wampee/grape winemaking with higher alcohols reduced by 24.99 %-26.76 % but with the content of ethanol, esters and organic acid unchanged significantly. Data above suggested that the combined addition of NH4+ and HPO42- could play synergistic effects on higher alcohol biosynthesis, which was an effective strategy to reduce higher alcohols in wines for improved qualities.