1. Laboratory of Biochemistry, Department of Biological and Chemical Engineering, Hachinohe National College of Technology, Hachinohe, 039-1192 Japan.
2. Corresponding author. E-mail: yama-c@hachinohe-ct.ac.jp.
3. A part of this work was presented at the Annual Meeting of the Japan Society for Bioscience and Biotechnology and Agrochemistry, Tokyo, April 1999.
4. Present address: Mitsubishi Chemicals Co. Ltd.