1. Institute of Microbial Chemistry, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan, Showa Pharmaceutical University, 3-3165 Higashitamagawa-gakuen, Machida-shi, Tokyo 194-8543, Japan, and TaKaRa Agri Co., Ltd., 2257 Noji-cho, Kusatsu-shi, Shiga 525-0055, Japan