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, (NH 4 ) 2 HPO 4 exhibited most excellent effects with higher alcohols reduced by 32.79%. Both NH 4 + and HPO 4 2- demonstrated individual capacities to reduce higher alcohol levels and transcriptome analysis was employed to investigate the synergistic mechanism. Results showed that both NH 4 + and HPO 4 2- could regulate higher alcohol biosynthesis, but with different regulators, Cat8 for the synergistic effect of NH 4 + and HPO 4 2- , and Ino80 for HPO 4 2- specifically. Meanwhile, HPO 4 2- reduced the activity of BCAT2, specifically and NH 4 + 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 HPO 4 2- or NH 4 + 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 NH 4 + and HPO 4 2- could play synergistic effects on higher alcohol biosynthesis, which was an effective strategy to reduce higher alcohols in wines for improved qualities.