초록
<P>Spent Sulfite Liquor (SSL) from wood pulping facilities is a sugar rich effluent that can be used as feedstock for ethanol production. However, depending on the pulping process conditions, the release of monosaccharides also generates a range of compounds that negatively affect microbial fermentation. In the present study, we investigated whether endogenous yeasts in SSL-based ethanol plant could represent a source of <I>Saccharomyces cerevisiae</I> strains with a naturally acquired tolerance towards this inhibitory environment. Two isolation processes were performed, before and after the re-inoculation of the plant with a commercial baker’s yeast strain. The isolates were clustered by DNA fingerprinting and a recurrent <I>Saccharomyces cerevisiae</I> strain, different from the inoculated commercial baker’s yeast strain, was isolated. The strain, named TMB3720, flocculated heavily and presented high furaldehyde reductase activity. During fermentation of undiluted SSL, TMB3720 displayed a 4-fold higher ethanol production rate and 1.8-fold higher ethanol yield as compared to the commercial baker’s yeast. Another non-<I>Saccharomyces cerevisiae</I> species, identified as the pentose utilizing <I>Pichia galeiformis</I>, was also recovered in the last tanks of the process where the hexose to pentose sugar ratio and the inhibitory pressure are expected to be the lowest.</P>