Alterations in d-amino acid concentrations and microbial community structures during the fermentation of red and white wines

Alterations in d-amino acid concentrations and microbial community structures during the fermentation of red and white wines were analyzed to clarify the relationship between the occurrence of d-amino acids and the actions of fermentative microorganisms. Relatives of Saccharomyces cerevisiae and Oenococcus oeni were detected in red wine samples, and relatives of S. cerevisiae, O. oeni, and Gluconacetobacter saccharivorans were detected in white wine samples. The S. cerevisiae relatives were detected throughout the fermentation process, whereas the O. oeni relatives were detected at the late stage of fermentation in both the red and white wine samples. The G. saccharivorans relative was detected in the early stage of fermentation. The amino acid analysis showed that d-alanine, d-glutamic acid, and d-lysine were present in both the red and white wine samples. The concentrations of these d-amino acids increased as the fermentation continued, especially from the malolactic fermentation stage to the end of the fermentation processes. These increases seem to be linked to the presence of O. oeni relatives.