1. Department of Applied Microbiology and Food Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, Canada S7N 5A8.
2. Corresponding author. Phone: 306/966-5030. Fax: 306/966-8898. E-mail: wangs@skyfox.usask.ca
3. Saskatchewan Research Council, 15 Innovation Boulevard, Saskatoon, SK, Canada S7N 2X8.
4. Department of Crop Science and Plant Ecology, University of Saskatchewan, SK, Saskatchewan.