1. Central Research Institutes, Taiyo Kagaku Co., Mie 510, Yokkaichi, Japan
2. Frontier Research Program, Laboratory for Intestinal Flora, RIKEN, Wako, Saitama, 351-01, Japan
3. Department of Biotechnology, Fukuyama University, Fukuyama City, 729-02, Japan
4. Faculty of Agriculture, The University of Tokyo, Tokyo, 113, Japan
5. The Institute of Physical & Chemical Research, Wako, Saitama, 351-01, Japan