1. Department of Computer Science, School of Computing, Tokyo Institute of Technology, Tokyo 152-8550, Japan
2. Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
3. Agricultural Bioinformatics Research Unit, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
4. Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo 113-8657, Japan