osmotolerant yeasts can grow; it was the case for Z. rouxii,
while the other osmotolerant yeast, C. pelliculosa, showed only
a weak growth after more than two days of culture (Fig. 1b).
Examination of Fig. 2 clearly shows that nitrogen was the
limiting substrate, since it was completely exhausted at the
end of growth, namelyafter about 42hof culture. Indeed, itwas
the case for the three yeasts for 174.0±0.2 kgm3 sugar content
in the medium (Fig. 2a) and only for Z. rouxii in the case of
358.0 ± 1.0 kgm3 sugar content in the medium (Fig. 2b).
As expected, there was a clear link between sugars consumption
and growth since both parameters followed similar
trends, namely a higher consumption was recorded for the
lowest amount of sugars (174.0 ± 0.2 kg m3) if compared to
358.0 ± 1.0 kg m3 (Table 1). For the non-inhibitory sugar
amount (174.0 ± 0.2 kg m3), a high yield of sugars consumption
was observed for the three yeasts after three days culture,
namely 94, 71 and 67% for S. cerevisiae, C. pelliculosa and Z.
rouxii respectively (Table 1).
The production of the main metabolites was also and as
expected linked to growth, since both ethanol and glycerol
productions were observed for the three yeasts for a sugar
content of 174.0 ± 0.2 kg m3 in the culture medium (Table 1);
while in the presence of 358.0 ± 1.0 kgm3 sugar content in the
medium, metabolites production was only observed for Z.
rouxii. It should be observed that the highest ethanol production
was observed for S. cerevisiae (Table 1), in agreement with