Different studies have been carried out in order
to obtain S. cerevisiae strains with greater salt and temperature
tolerance. For example, Morimura et al. (1997) developed
by protoplast fusion and manipulating culture
conditions, flocculating strains capable of growing at
35 C and at molasses concentration of 22% (w/v). Under
these conditions and using repeated-batch cultures at laboratory
scale, ethanol concentration of 91 g/L and productivities
of 2.7 g/(L h) were obtained. However, the
principal approach for avoiding the negative influence of salts and other compounds on the fermentation is through
the conditioning of molasses by the addition of different
compounds neutralizing the inhibitory effects of the medium
components. In addition, molasses should be supplemented
with nutritional factors promoting the yeast
growth.