Xylan-degrading activity in yeasts: growth on xylose, xylan and hemicelluloses.

The ability to grow in liquid media with D-xylose, xylan from decidous trees, and hemicelluloses from conifers was tested in 95 strains of 35 genera of yeasts and yeast-like organisms. Of 54 strains thriving on xylose, only 13 (genera Aureobasidium, Cryptococcus and Trichosporon) utilized xylan and hemicelluloses as growth substrates. The árowth media of these strains were found to contain xylan-degrading enzymes splitting the substrate to xylose and a mixture of xylose oligosaccharides. The ability of these yeasts to utilize the wood components (hitherto unknown in the genus Crytococcus) makes them potential producers of microbial proteins from industrial wood wastes containing xylose oligosaccharides, xylan, and hemicelluloses as the major saccharide components without previous saccharification.