A study of the yeast mycobiota in stored timber was conducted. Heartwood, sapwood, and bark samples of American-basswood, black- cherry, black-locust, red-oak, soft-maple, and white-poplar logs scheduled for processing at a sawmill in West Virginia were collected at various times during a year and analyzed for yeasts and yeast like fungi. The overall concentrations of yeasts and yeast like fungi ranged up to 10(8) colony forming units per gram. The concentrations were much higher during the summer than during the winter months. The highest concentrations were found in American- basswood, followed by black-locust, soft-maple, red-oak, black- cherry, and white-poplar in that order. Across all species the highest yeast concentrations were found in the sapwood, followed by the bark and heartwood which had similar concentrations. Pichia (Hansenula) was the major yeast species identified. It was found primarily in timber samples taken in August and sapwood from American-basswood, black-locust, and black-cherry. Candida-sake, Rhodotorula-glutinis, Cryptococcus-laurentii, and Cryptococcus- albidus were other major yeast species identified. The authors conclude that high concentrations of yeasts which could be major components of aerosols generated during lumber processing may be found in stored timber logs. These could be responsible, at least in part, for pulmonary disorders that have been observed in sawmill workers.
Biodeterioration and Biodegradation 8: Proceedings of the 8th International Biodeterioration and Biodegradation Symposium, Windsor, Ontario, Canada