In countries where ethanol is produced in large scale by-product utilization has become an important issue in making ethanol
production less polluting and more profitable. Among these byproducts, fusel oil obtained from distillation of fermented agricultural products is currently used as raw material for the production
of the amyl and butyl alcohols. However, a great portion of fusel oil
has generally been discarded . Main components of fusel oil are ethanol (13%), butanol (15%), and amyl alcohols (51%). Remaining constituents are small proportions of other
secondary alcohols and water (15%). The yeast Williopsis saturnus
can convert higher alcohols into the corresponding acetates , for example the concentration of isoamyl acetate can
be increased by addition of fusel oil as a cheap source of higher
alcohols to fermentation medium.