1. Department of Microbiology, Faculty of Pharmaceutical Sciences; Okayama University; Okayama Okayama 700-8530 Japan
2. Laboratory of Pathogenic Microbiology, Department of Biological Pharmacy, School of Pharmacy; Shujitsu University; Okayama Okayama 703-8516 Japan
3. Department of Pharmacognosy, Faculty of Pharmaceutical Sciences; Okayama University; Okayama Okayama 700-8530 Japan