1. Department of Microbiology and Infection; Faculty of Medicine; Kochi University; Kochi; Japan
2. Research Institute of Molecular Genetics; Kochi University; Kochi; Japan
3. Department of Oral Microbiology; Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences; Okayama; Japan
4. Science Research Center; Kochi University; Kochi; Japan