1. Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
2. Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen Street, Sault Ste. Marie, ON P6A 5M7, Canada.
3. Department of Wood Science, Faculty of Forestry, University of British Columbia, 4035-2424 Main Mall, Vancouver, BC V6T 1Z4, Canada.