In mixed cultures, yeast growth was determined by plate counting
on 2 different agar media. Samples were withdrawn throughout fermentation
and diluted appropriately. Non-Saccharomyces cells were
counted using a specific agar medium (NS): YPDA (1% yeast extract,
1% peptone, 2% dextrose, 2% agar; pH 4.8) supplemented with 1 μg/mL
cycloheximide to promote the growth of T. delbrueckii Alpha and inhibit
that of S. cerevisiae X5. The number of S. cerevisiae was given as the difference
between the total plate count using YPDAmediumand the plate
count using NS medium. Yeast growth in single cultures was determined
using only the YPDA medium. Plates were incubated at 24 °C
for 4 days before counting.
The level of yeast population was only measured for experiments
carried out in laboratory.