The seagrass seeds were collected with the kind cooperation of former chief executive officer of the late Kazushi Honda and members of Hinase-cho Fisheries Cooperative Association. This study was supported by a fund (Suisan-biomass no Shigenka-gijutsu Kaihatsu-jigyo, the fund for developing technology for utilization of fisheries biomass resources) from the Fisheries Agency, Japan. The authors are grateful to Dr. Yasufumi Mishima for giving opportunities at times to discuss on strategy for bioethanol production from seaweeds.