Nitrogen Preferences during Alcoholic Fermentation of Different Non-Saccharomyces Yeasts of Oenological Interest

Abstract

Non-Saccharomyces yeasts have long been considered spoilage microorganisms. Currently, oenological interest in those species is increasing, mostly due to their positive contribution to wine quality. In this work, the fermentative capacity and nitrogen consumption of several non-Saccharomyces wine yeast (Torulaspora delbrueckii, Lachancea thermotolerans, Starmerella bacillaris, Hanseniaspora uvarum, and Metschnikowia pulcherrima) were analyzed. For this purpose, synthetic must with three different nitrogen compositions was used: a mixture of amino acids and ammonium, only organic or inorganic nitrogen. The fermentation kinetics, nitrogen consumption, and yeast growth were measured over time. Our results showed that the good fermentative strains, T. delbrueckii and L. thermotolerans, had high similarities with Saccharomyces cerevisiae in terms of growth, fermentation profile, and nitrogen assimilation preferences, although L. thermotolerans presented an impaired behavior when only amino acids or ammonia were used, being strain-specific. M. pulcherrima was the non-Saccharomyces strain least affected by the nitrogen composition of the medium. The other two poor fermentative strains, H. uvarum and S. bacillaris, behaved similarly regarding amino acid uptake, which occurred earlier than that of the good fermentative species in the absence of ammonia. The results obtained in single non-Saccharomyces fermentations highlighted the importance of controlling nitrogen requirements of the wine yeasts, mainly in sequential fermentations, in order to manage a proper nitrogen supplementation, when needed.

Isotopic Tracers Unveil Distinct Fates for Nitrogen Sources during Wine Fermentation with Two Non-Saccharomyces Strains

“…This has to be considered with respect to the lower anabolic requirement of M. pulcherrima (final biomass content: 1.6 g/L) compared to T. delbrueckii (4.1 g/L). This lower biomass production by M. pulcherrima during fermentation was also observed by Roca-Mesa et al [ 29 ]. Furthermore, while T .…”

Modulating Wine Aromatic Amino Acid Catabolites by Using Torulaspora delbrueckii in Sequentially Inoculated Fermentations or Saccharomyces cerevisiae Alone

“…Therefore, using T. delbrueckii as a starting culture in winemaking should not influence the growth and the metabolic activity of S. cerevisiae (Figure 2) too badly. Generally, the results about the three amino acids' consumption during fermentation are in accordance with the literature [9,15,16,24,31], since their concentration decreased quickly mainly during the logarithmic phase of cell growth ( Figure 2) by covering the needs of the yeasts in nitrogen. Finally, chardonnay must fermented by S. cerevisiae QA and RF showed an increase of PHE and NIC concentrations in the last part of fermentation (Table S2 and Figures S3 and S4).…”

“…In addition, in QA and RF fermentations, the amino acids were consumed much faster than in samples sequentially inoculated with T. delbrueckii and S. cerevisiae QA23, with a trend similar as the one of TRP in Figure 5 (see also Table S2 and Figures S2-S4). The preference of Td for ammonium sulphate and then for amino acids as nitrogen sources [31] might explain this data. These results could be a positive indication that T. delbrueckii has different orders of nitrogen preference compared to S. cerevisiae, and so its impact on sequentially fermentation is not so competitive as far as nitrogen consumption is concerned.…”

The Genus Metschnikowia in Enology

“…These studies, which examined both single and mixed fermentations employing M. pulcherrima and S. cerevisiae , reported that at the end of the fermentation a significant amount (up to 40%) of the studied NAS had not been consumed when single cultures of the non-S accharomyces species were used, whereas Saccharomyces consumed all the nitrogen sources present in the media, including in mixed cultures [ 49 ]. In a recent study, M. pulcherrima is the least influenced yeast species by the must nitrogen composition [ 50 ].…”

“…According to several works, the decrease in volatile acidity when M. pulcherrima is used varies between 10% and 75% [ 40 , 41 , 50 ], indicating that the reduction of volatile acidity in such conditions seems to be a trend. However, other studies have reported equal quantities of acetic acid when sequential fermentation was employed [ 21 , 26 ], or even an increase of around 20% [ 29 ].…”