A study into the role of L-aspartic acid on the metabolism of L-malic acid and D-glucose by Oenococcus oeni.

AIMS

The purpose of this work was to study the effect of L-aspartic acid concentration on bacterial growth, D-glucose fermentation and L-malic acid consumption of Oenococcus oeni NCFB 1707.

METHODS AND RESULTS

Bacterial cultures were performed in synthetic media. Bacterial growth, D-glucose fermentation and L-malic acid consumption were reduced when L-aspartic acid concentration became excessive. This inhibitory effect of high concentrations of L-aspartic acid on bacterial growth was also observed with several Oenococcus oeni strains, except O. oeni BL01. The L-aspartic acid inhibitory effect on bacterial growth could be reduced by increasing the concentration of L-glutamic acid. L-glutamic acid transport was found to be competitively inhibited by L-aspartic acid. In addition, an excessive amount of L-aspartic acid modified D-glucose metabolism, with an overproduction of acetic acid and reduced ethanol production.

CONCLUSION

Since L-glutamic acid is an essential amino acid for the bacterial strain used, the L-aspartic acid inhibitory effect on bacterial growth could be linked to its involvement in an antagonistic interaction with L-glutamic acid.

SIGNIFICANCE AND IMPACT OF THE STUDY

Such antagonistic interactions between amino acids in O. oeni strains could be another explanation for the difficulties of inducing malolactic fermentation in wines.