The yeast Torulaspora quercuum efficiently produced ethanol with yield up to 59.9 g L−1 from 200 g L−1 galactose.
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T. quercuum isolates KRT82 and KRT85 flocculated well in agar- and red seaweed-hydrolysate.
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Efficient ethanol production from red-algal-hydrolysate was demonstrated by KRT85 during repeated batch fermentation.
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The productivity reached 0.98 g L−1 working volume h−1 during repeated batch culture.
Abstract
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.
