1. Department of Biosciences, Teikyo University, 1-1 Toyosatodai, Utsunomiya 320-8551, Japan
2. Advanced Instrumental Analysis Center, Teikyo University, 1-1 Toyosatodai, Utsunomiya 320-8551, Japan
3. Division of Microbiology, National Institute of Health Sciences, Kanagawa 210-9501, Japan