Studies on growth and metabolism of Oenococcus oeni on sugars and sugar mixtures

To study the effect of sugars and sugar mixtures on the growth kinetics of Oenococcus oeni NCIMB 11648 in batch culture with the aim of producing a high cell productivity system for starter cultures.

The growth of O. oeni was investigated on single sugars (glucose, fructose or sucrose) and their mixtures (glucose-fructose, glucose-sucrose or fructose-sucrose). Better growth was obtained on sugar mixtures compared with growth on a single sugar. The production system of O. oeni biomass was investigated in batch culture with or without pH control with respect to kinetics, specific growth rate and biomass yield. The effect of pH and substrate concentration on fermentation balances and ATP yield were determined. The optimal growth of O. oeni was achieved on the glucose-fructose mixture (9 g l(-1), 1 : 1) at pH 4.5 and 25 degrees C with pH control, with highest cell volumetric productivity (7.9 mg cell l(-1) h(-1)), biomass yield (0.041 g cell g(-1) sugar) and specific growth rate (0.066 h(-1)).

The limitations to the growth of O. oeni were pH and inhibition by end product resulting in poor utilization of the medium with low cell yields. The cell productivity of the system can be improved by the appropriate use of mixed sugar growth medium.

This study uniquely showed that appropriate sugar mixtures with the correct environmental conditions can significantly improve the productivity of O. oeni cultures.