Torulaspora quercuum shows great potential for bioethanol production from macroalgal hydrolysate

Yeast fermenting galactose (Gal) to ethanol are key to develop bioethanol production from galactan-rich red algal feedstock. To improve Gal -based bioethanol production, the potential of non-Saccharomyces yeast was investigated with screening Gal -fermenting yeast from environment in this study. Isolates, Torulaspora quercuum strains KRT82 and KRT85 were successfully effectively produced 54.77 +/- 2.18 and 59.92 +/- 2.18 g L-1 ethanol, respectively, from 200 g L-1 Gal as the carbon source in modified yeast-malt broth. The ethanol yield reached nearly corresponding to the theoretical yield. The isolates produced 8-10 g L-1 ethanol from Gelidiaceae hydrolysate containing approximately 20 g L-1 Gal and 10-13 g L-1 glucose, with an ethanol yield of 54%-57%. The cells flocculated. During repeated batch fermentation, the ethanol yield were reached to 38 g L -1 -working volume for 39 h, and the productivity of ethanol reached 0.98 g L-1 working volume h-1.