• flow cytometry;
  • fluorescent antibodies;
  • malolactic fermentation;
  • Oenococcus;
  • wine


Aims:  To monitor in real-time the changes in microbial populations and chemistry of grape juice simultaneously inoculated with Saccharomyces cerevisiae and Oenococcus oeni.

Methods and Results:  Viable populations of S. cerevisiae and O. oeni in Chardonnay fermentations were identified and quantified using fluorescent dyes and fluorescently labelled antibodies in a flow cytometric assay. Fermentation chemistry was monitored using Fourier transform infrared (FTIR) spectroscopy, except for malic acid which was measured enzymatically. Malic acid utilization by O. oeni was greatest in the presence of the yeast Cepage. Growth of O. oeni was substantially slower in the presence of the yeast VL1. The three yeasts had similar fermentation rates in the presence and absence of O. oeni.

Conclusions:  Viable and nonviable yeast and bacterial populations can be rapidly discriminated in simultaneous malolactic-alcoholic wine fermentations using antibodies, fluorescent dyes and flow cytometry.

Significance and Impact of the Study:  This is the first study using fluorescently labelled antibodies to discriminate and monitor yeast and bacterial populations in wine fermentations and offers a new approach to investigating microbial interactions in wine fermentations.