Comparison of ethanol productivity among yeast strains using three different seaweeds

This study compared the ethanol productivity of different yeast strains using three different seaweed species as fermentation feedstocks. Each seaweed was saccharified by treatment with 3 % (v/v) sulfuric acid and cellulase. Ulva spp., Gracilaria spp. and Costaria costata yielded 0.22, 0.16, and 0.10 g of reducing sugars per 1 g of dried seaweed powder, respectively. Among the yeast strains tested, the marine-derived C-19 had maximum ethanol productivity, with production of 0.15, 0.08, and 0.05 g of ethanol from saccharified solutions containing 1 g of Ulva spp., Gracilaria spp., and C. costata powder, respectively. By the optimization of pretreatment, saccharification and fermentation conditions, C-19 yeast became capable of producing 0.09 g of ethanol from the alginate-extracted residue of C. costata. Finally, to evaluate the robustness of our measurements, we performed scale-up saccharification and fermentation using a jar fermentor. The productivity of both saccharification and fermentation were similar across both scales. Thus, we confirmed that the ethanol fermentation conditions from seaweeds powders in this study are appropriate even at larger scales.