Production of 16.5% v/v ethanol from seagrass seeds

Ethanol fermentation on seeds of seagrass Zostera marina was studied. The seeds were collected from the annual plant colony of Z. marina at Hinase Bay, Okayama. The seeds contained 83.5% carbohydrates including 48.1% crude starch on a dry weight basis, which is comparable to cereals such as wheat flour and corns. The seeds were saccharified with glucoamylase (50°C, 96 h) and 103.4 g/l concentration of glucose juice was obtained. The glucose juice was further fermented (23°C–35°C, 15 days) with Saccharomyces cerevisiae strains NBRC10217T and Kyokai 7-go, and ethanol was obtained at a 65.0 g/l (82.3 ml/l) level by monographic double-fermentation and at a 130.4 g/l (165.1 ml/l) level by parallel double-fermentation. Fermented products of seagrass seeds containing such a high ethanol concentration as the present study have potential to be utilized not only for biofuel but also for foods and beverages in the future. Culturing of seagrass seeds as a crop may enable development of a new marine fermentation industry.