1. Division of Oral Biological Sciences, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan
2. Department of Microbiology, Saga Medical School, Saga 849-8501, Japan
3. Department of Molecular Enzymology, Kumamoto University Graduate School of Medical Sciences, Kumamoto 860-8556, Japan
4. Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan
5. Department of Microbiology, Solution Oriented Research for Science and Technology, Kinki University School of Medicine, Osaka-Sayama, Osaka 589-8511, Japan