Nitrogen utilization diversity in Torulaspora delbrueckii isolates relevant to food and beverage fermentations

Nitrogen metabolism plays a crucial role in the growth, fermentation performance, and aroma production of yeasts during alcoholic fermentation. While this process is well-understood in Saccharomyces cerevisiae (Sc), knowledge remains limited regarding non-Saccharomyces yeasts. These yeasts, like T. delbrueckii (Td), are gaining popularity in winemaking due to their ability to enhance the wine's organoleptic properties, including improving aroma complexity and mouthfeel, and reducing volatile acidity. To address the limited understanding of the variability in amino acid utilization linked to genomic diversity within Td, we investigated growth patterns, and key gene repertoire of fifteen Td strains under various nitrogen conditions, comparing them to a commercial Sc strain. The results evidenced varied growth profiles and nitrogen preferences, particularly pronounced for cysteine. Intraspecies diversity was evident in metabolic activity and efficiency of adaptation to the different nitrogen conditions. Unlike Sc, Td displays the ability to grow on cysteine and generally exhibits a shorter lag phase across nitrogen sources. Td's genomic analysis revealed that some specific nitrogen transporter genes (ATF1-2, HIP1, TAT1-2) were absent, while others were duplicated (YCT1, SAM3). These variations likely shape Td's unique nitrogen uptake patterns. For instance, despite lacking specific branched-chain amino acid transporters, Td utilized these amino acids, likely through broader-specificity transporters, although it exhibits differential preferences for leucine versus valine. Overall, this work highlights important genotypic and phenotypic differences between Sc and Td, along with high intraspecific diversity within Td, emphasizing nitrogen nutrition's crucial role in growth and its implications for winemaking strain selection programs and co-culture strategies.