1. Department of Microbiology, Faculty of Medicine, Kagawa University, Takamatsu, Kagawa 761‑0793, Japan
2. Division of Biology, Hyogo College of Medicine, Nishinomiya, Hyogo 663‑8501, Japan
3. Faculty of Nursing, Shikoku University, Ohjin, Tokushima 771‑1192, Japan
4. Laboratory for Oral Health Science, Tokyo 103‑0012, Japan