Yeasts capable of fermenting both o-xylose and cellobiose
to ethanol were screened. Of 213 species of yeasts surveyed, Kluyveromyces cellobiovorus sp. nov.. a new species belonging to genus of Kluyveromyces, was selected as the sole strain. This strain accumulated 32, 22, and 19 g/L of ethanol from WO glucose, 0-xylose, and cellobiose. respectively. It was also shown that this strain produced ethanol from the enzymatic bagasse hydrolysate containing hexoses and pentoses more efficiently than Saccharomyces cerevisiae.
JNTRODUCTlON
Renewable cellulosic biomass contains three major components: lignin, cellulose, and hemicellulose. The hemicellulose as well as the cellulose fraction must be utilized to develop an economic process for the production of ethanol from the biomass. The main hydrolysis product of the hemicellulose is Dxylose, which the current industrial alcoholic yeasts such as Saccharomyces cannot ferment. It would thus be interesting to obtain a yeast strain able to ferment not only glucose but also Dxylose.
Until fairly recently, yeasts have been considered unable to ferment Dxylose to ethanol, even though many yeasts are known to assimilate Dxylose oxidatively.'' Since 1981, however, promising studies have been reported regarding the fermentation of Dxylose to ethanol, under semiaerobic conditions, by the yeast Pachysofen tannophifusss and Candida tropicalis6 and aerobically by a mutant strain of Candida sp.' .' and Kluyveromyces rnar~ianus.~