1. Laboratory of Microbial Physiology, Research Faculty of Agriculture, Hokkaido University, Kita-9 Nishi-9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
2. Present address: Faculty of Agriculture, Setsunan University, 45-1 Nagaotouge-cho, Hirakata-shi, Osaka 573-0101, Japan