1. Bioscience Education and Research Center, Akita University, 1-1-1, Hondo, Akita 010-8543, Japan
2. Department of Microbiology, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo 060-8556, Japan
3. Department of Chemistry, University of Guelph, Guelph, ON, Canada N1G 2W1