1. Department of Microbiology, Faculty of Medicine, Kagawa University, 1750-1 Miki-cho, Kita-gun, Kagawa 761-0793, Japan
2. Department of Food and Nutritional Sciences, College of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
3. Department of Human Nutrition, Faculty of Contemporary Life Science, Chugokugakuen University, 83 Niwase, Kita-ku, Okayama 701-0197, Japan