Saccharomyces cerevisiae HAU-1, a time tested industrial yeast possesses most of the desirable fermentation
characteristics like fast growth and fermentation rate, osmotolerance, high ethanol tolerance, ability to
ferment molasses, and to ferment at elevated temperatures etc. However, this yeast was found to be sensitive
against the killer strains of Saccharomyces cerevisiae. In the present study, killer trait was introduced into
Saccharomyces cerevisiae HAU-1 by protoplast fusion with Saccharomyces cerevisiae MTCC 475, a killer
strain. The resultant fusants were characterized for desirable fermentation characteristics. All the
technologically important characteristics of distillery yeast Saccharomyces cerevisiae HAU-1 were retained
in the fusants, and in addition the killer trait was also introduced into them. Further, the killer activity was
found to be stably maintained during hostile conditions of ethanol fermentations in dextrose or molasses, and
even during biomass recycling.
