ABSTRACT
In order to compare the characteristics of ethano l production, a serie s respiratory deficient mutants (rho -) of Saccharomyces cerevisiae and the ir wil d parent strain (rho +) were assayed for ethanol yield, ethanol fermentation ki netics, ethanol tolerance, and activities of ethanol-dehydrogenase. The data i nd icated that: Though the average amount of ethanol produced by mutants rho - a nd by wild rho + strains were similar, some mutants produced a little more amount of ethanol than wild type. The kinetics curve of ethanol fermentation suggested t h at rho - mutants had a little higher ethanol fermenting speeds than wild type . Th e activity of ethanol-dehydrogenase per unit weight of protein of rho - mutan ts c ells were higher than that of wild strain rho +; the activity of ethanol-dehyd rogenase per unit volume of fermentation medium of rho + were higher than that rho - mutants,mainly due to the higher biomass of rho + were higher than that of rho - mutan ts. Some rho - mutants could tolerate higher ethanol concentration than wild rh o + stra in, but some not. If higher ethanol tolerance and higher ethanol yield rho - mu tants were used in fermenting process,higher ethanol yield would be expected,but some problems such as that rho - mutants grew slowly should be considered.