Biohydrogen production from beet molasses by sequential dark and photofermentation

E. Özgür, A.E. Mars, B. Peksel, A. Louwerse, M. Yücel, U. Gündüz, P.A.M. Claassen, I. Eroglu

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187 Citations (Scopus)


Biological hydrogen production using renewable resources is a promising possibility to generate hydrogen in a sustainable way. In this study, a sequential dark and photofermentation has been employed for biohydrogen production using sugar beet molasses as a feedstock. An extreme thermophile Caldicellulosiruptor saccharolyticus was used for the dark fermentation, and several photosynthetic bacteria (Rhodobacter capsulatus wild type, R. capsulatus hup- mutant, and Rhodopseudomonas palustris) were used for the photofermentation. C. saccharolyticus was grown in a pH-controlled bioreactor, in batch mode, on molasses with an initial sucrose concentration of 15 g/L. The influence of additions of NH4+ and yeast extract on sucrose consumption and hydrogen production was determined. The highest hydrogen yield (4.2 mol of H2/mol sucrose) and maximum volumetric productivity (7.1 mmol H2/Lc.h) were obtained in the absence of NH4+. The effluent of the dark fermentation containing no NH4+ was fed to a photobioreactor, and hydrogen production was monitored under continuous illumination, in batch mode. Productivity and yield were improved by dilution of the dark fermentor effluent (DFE) and the additions of buffer, iron-citrate and sodium molybdate. The highest hydrogen yield (58% of the theoretical hydrogen yield of the consumed organic acids) and productivity (1.37 mmol H2/Lc.h) were attained using the hup- mutant of R. capsulatus. The overall hydrogen yield from sucrose increased from the maximum of 4.2 mol H2/mol sucrose in dark fermentation to 13.7 mol H2/mol sucrose (corresponding to 57% of the theoretical yield of 24 mol of H2/mole of sucrose) by sequential dark and photofermentation.
Original languageEnglish
Pages (from-to)511-517
JournalInternational Journal of Hydrogen Energy
Issue number2
Publication statusPublished - 2010


  • rhodobacter-sphaeroides ou001
  • ethanol-type fermentation
  • hydrogen-production
  • caldicellulosiruptor-saccharolyticus
  • anaerobic fermentation
  • photo-fermentation
  • capsulatus
  • bioreactor
  • pathway
  • reactor


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