1. Laboratory of Food Biotechnology, Department of Bioscience and Biotechnology, Division of Bioresource and Bioenviromental Science, Graduate School of Kyushu University, Fukuoka 812-8581, Japan, and School of Bioresources, Hiroshima Prefectural University, 562 Nanatsuka-cho, Shobara, Hiroshima 727-0023, Japan