The Timing of Nitrogen Addition Impacts Yeast Genes Expression and the Production of Aroma Compounds During Wine Fermentation

Abstract

Among the different compounds present in the must, nitrogen is an essential nutrient for the management of fermentation kinetics but also plays an important role in the synthesis of fermentative aromas. To address the problems related to nitrogen deficiencies, nitrogen additions during alcoholic fermentation have been implemented. The consequences of such additions on the main reaction are well known. However, their impact on aromas synthesis is still poorly understood. So, the main objective of this study was to determine the impact of nitrogen addition during the stationary phase on both the fermentation kinetics and aroma synthesis. To reach this goal, we used a transdisciplinary approach combining statistical modeling (Box-Behnken design and response surface modeling) and gene expression study (transcriptomic analysis). Our results indicated that nitrogen metabolism, central carbon metabolism (CCM), fermentation kinetics and aroma production were significantly impacted by nitrogen addition. The most remarkable point was the different regulation of the bioconversion of higher alcohols into acetate esters on one hand and of fatty acids into ethyl esters on the other hand. We highlighted that the conversion of higher alcohols into acetate esters was maximum when nitrogen was added at the beginning of the stationary phase. Conversely, the highest conversion of acids into ethyl esters was reached when nitrogen was added close to the end of the stationary phase. Moreover, even if the key element in the production of these two ester families appeared to be the enzymatic activity responsible for their production, rather than the availability of the corresponding precursors, these enzymatic activities were differently regulated. For acetate esters, the regulation occurred at gene level: the ATF2 gene was overexpressed following nitrogen addition during the stationary phase. On the opposite, no induction of gene expression was noted for ethyl esters; it seemed that there was an allosteric regulation.

Modelling the physiological status of yeast during wine fermentation enables the prediction of secondary metabolism

“…This recent dataset offers the possibility to validate or invalidate some of the modelling assumptions described in this work. In this respect, consistent with the observations of Godillot et al ( 2022 ) our model predicts that the addition of nitrogen results in an increase in the final amount of PEA. However, the same authors did not observe the effect on the production of isoamyl alcohol that we predicted with our model.…”

“…Recently, Godillot et al ( 2022 ) investigated the aroma composition of wines with varying initial nitrogen (amino acids with diphosphate ammonia), added nitrogen and the timing of nitrogen addition. This recent dataset offers the possibility to validate or invalidate some of the modelling assumptions described in this work.…”

Analysis of volatile compounds production kinetics: A study of the impact of nitrogen addition and temperature during alcoholic fermentation

“…The production kinetics of isoamyl acetate, whether in liquid or in terms of total production, are impacted by the interaction of the three factors studied. These interactions are particularly important and mask some effects previously reported in the literature, such as the simple effect of initial nitrogen concentration (Hernandez-Orte et al, 2006;Rollero et al, 2015;Seguinot et al, 2018;Godillot et al, 2022). Indeed, depending on the concentration of added nitrogen or fermentation temperature, a high concentration of initial nitrogen is not necessarily associated to a very important 10.3389/fmicb.2023.1124970 isoamyl acetate production.…”

“…To overcome nitrogen deficiencies in musts, nitrogen addition during fermentation has become a regular method. In addition to reducing fermentation duration, it promotes the synthesis of acetate esters and propanol ( Seguinot et al, 2018 ; Godillot et al, 2022 ). Indeed, it was recently shown that nitrogen addition at the beginning of the stationary phase of fermentation activated the ATF2 gene that codes for one of the isoenzymes responsible for the synthesis of acetate esters ( Godillot et al, 2022 ).…”

“…In addition to reducing fermentation duration, it promotes the synthesis of acetate esters and propanol ( Seguinot et al, 2018 ; Godillot et al, 2022 ). Indeed, it was recently shown that nitrogen addition at the beginning of the stationary phase of fermentation activated the ATF2 gene that codes for one of the isoenzymes responsible for the synthesis of acetate esters ( Godillot et al, 2022 ). This overexpression resulted in maximizing the synthesis of this aromatic family.…”