title: Critical analysis of hydrogen production from mixed culture fermentation under thermophilic condition (60 °C).
abstract: Bio-hydrogen production from mixed culture fermentation (MCF) of glucose was studied by conducting a comprehensive product measurement and detailed mass balance analysis of their contributions to the final H2 yield. The culture used in this study was enriched on glucose at 60 °C through a sequential batch operation consisting of daily glucose feeds, headspace purging and medium replacement every third day in serum bottles for over 2 years. 2-Bromoethanesulfonate (BES) was only required during the first three 3-day cycles to permanently eliminate methanogenic activity. Daily glucose feeds were fully consumed within 24 h, with a persistent H2 yield of 2.7 ± 0.1 mol H2/mol glucose, even when H2 was allowed to accumulate over the 3-day cycle. The measured H2 production exceeded by 14 % the theoretical production of H2 associated with the fermentation products, dominated by acetate and butyrate. Follow-up experiments using acetate with a (13)C-labelled methyl group showed that the excess H2 production was not due to acetate oxidation. Chemical formula analysis of the biomass showed a more reduced form of C5H11.8O2.1N1.1 suggesting that the biomass formation may even consume produced H2 from fermentation.
authors.affiliation: Centre for Solid Waste Bioprocessing, School of Civil Engineering, The University of Queensland, Brisbane, 4072, Queensland, Australia.|School of Earth Sciences, The University of Queensland, Brisbane, 4072, Queensland, Australia.
authors.forename: Hang
authors.initials: H
authors.lastname: Zheng
authors.affiliation: CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei, 230026, China. rzeng@ustc.edu.cn.
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Zeng
authors.affiliation: Centre for Solid Waste Bioprocessing, School of Civil Engineering, The University of Queensland, Brisbane, 4072, Queensland, Australia.|CSIRO Agriculture, Underwood Ave, Floreat, WA, Australia.
authors.forename: Cathryn
authors.initials: C
authors.lastname: O'Sullivan
authors.affiliation: Centre for Solid Waste Bioprocessing, School of Civil Engineering, The University of Queensland, Brisbane, 4072, Queensland, Australia. william.clarke@uq.edu.au.
authors.forename: William P
authors.initials: WP
authors.lastname: Clarke
mesh_terms: D000085:Acetates / Q000378:metabolism; D017738:Alkanesulfonic Acids / Q000737:chemistry; D000693:Anaerobiosis; D061249:Batch Cell Culture Techniques; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D002087:Butyrates / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry*; D004269:DNA, Bacterial / Q000302:isolation & purification; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006358:Hot Temperature; D006859:Hydrogen / Q000378:metabolism*; D007218:Industrial Microbiology; D008962:Models, Theoretical; D017422:Sequence Analysis, DNA; D046950:Thermoanaerobacterium / Q000378:metabolism
chemical_list: D000085:Acetates; D017738:Alkanesulfonic Acids; D002087:Butyrates; D003470:Culture Media; D004269:DNA, Bacterial; D002245:Carbon Dioxide; C018853:2-bromoethanesulfonic acid; D006859:Hydrogen; D005947:Glucose
keywords: Bio-hydrogen; Biomass formation; Excess H2 production; Mixed culture fermentation; Stable isotope