1. Laboratory of Food Microbiology and Food Safety; Department of Health and Environmental Sciences; School of Veterinary Medicine; Rakuno Gakuen University; 582 Bunkyoudai-Midorimachi, Ebetsu, 069-8501 Japan
2. Department of Microbiology; Sapporo Medical University School of Medicine; S1 W17, Chuo-ku, Sapporo, 060-8556 Japan
3. Laboratory of Animal Health; Department of Health and Environmental Sciences; School of Veterinary Medicine; Rakuno Gakuen University; Ebetsu 069-8501 Japan