1. Department of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe 657-8501, Japan
2. Graduate School of Medicine, Mie University, Tsu 514-8507, Japan
3. Department of Microbiology, School of Biological Sciences, Southern Illinois University, Carbondale, Illinois 62901, United States
4. Faculty of Science, Ibaraki University, Mito 310-8512, Japan