1. Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
2. Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
3. Graduate School of Science, Osaka City University, 3-3-138, Sugimoto,
Sumiyoshi-ku, Osaka-shi, Osaka 558-8585, Japan