Cascade bioethanol productions from glucose and mannitol in saccharified kombu Laminariaceae by anaerobic and aerobic fermentations with two kinds of yeast

In this paper, cascade bioethanol productions from glucose and mannitol in the saccharified kombu (Laminariaceae) by two kinds of yeast were examined respectively. Mannitol exists as monosaccharide and glucose is polymerized to polysaccharides膨ellulose, hemicellulose, and laminaran in brown algae. There have been only a few reports about ethanol production from mannitol by yeasts. Therefore, screening of mannitol-fermenting yeasts was carried out from both coastal waters and culture collections of the research institute in Japan. All sixteen NBRC strains of Saccharomyces paradoxus were found to produce 22-35 g/L of bioethanol aerobically from 100 g/L of mannitol at 30 ｰC for 5-7 days. Thus, the cascade bioethanol production system was constructed from the saccharified solution of kombu with anaerobic fermentation with marine-derived Saccharomyces cerevisiae C-19 (Takagi et al., 2015; Obara et al., 2015; Takagi et al., 2012a) followed with aerobic fermentation with S. paradoxus NBRC10553. In this system, 1.1 g/L of bioethanol was produced with the strain C-19 in the first step and 7.9 g/L of bioethanol was produced with the strain NBRC10553 in the second step from the saccharified kombu.