Abstract
Three continuous stirred-tank reactors (CSTRs) were used for H(2) production from molasses wastewater at influent pH of 6.0-6.5 (reactor A), 5.5-6.0 (reactor B), or 4.0-4.5 (reactor C). After operation for 28 days, the microbial community formed ethanol type (C), propionate type (A) and ethanol-butyrate-mixed type (B) fermentation. The H(2) production rate was the highest for ethanol type fermentation, 0.40 l (g VSS)(-1) day(-1) or 0.45 l H(2) (g COD removed)(-1). Microbial community dynamics and diversity were analysed using double-gradient denaturing gradient gel electrophoresis (DG-DGGE). Denaturing gradient gel electrophoresis profiles indicated that the community structures changed quickly in the first 14 days. Phylogenetic analysis indicated that the dominant bacterial groups were low G+C Gram-positive bacteria, Bacteroides, gamma-Proteobacteria and Actinobacteria; alpha-Proteobacteria, beta-Proteobacteria, delta-Proteobacteria and Spirochaetes were also presented as minor groups in the three reactors. H(2)-producing bacteria were affiliated with Ethanoligenens, Acetanaerobacterium, Clostridium, Megasphaera, Citrobacter and Bacteroides. An ethanol-based H(2)-producing bacterium, Ethanoligenens harbinense CGMCC1152, was isolated from reactor C and visualized using fluorescence in situ hybridization (FISH) to be 19% of the eubacteria in reactor C. In addition, isoenzyme activity staining for alcohol dehydrogenase (ADH) supported that the majority of ethanol-producing bacteria were affiliated with Ethanoligenens in the microbial community.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacteria, Anaerobic / classification
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Bacteria, Anaerobic / metabolism*
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Bioreactors
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Conservation of Energy Resources / methods*
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DNA Fingerprinting
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Ecosystem*
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Ethanol / metabolism*
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Fermentation
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Food-Processing Industry
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Hydrogen / metabolism*
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Hydrogen-Ion Concentration
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In Situ Hybridization, Fluorescence
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Molasses / microbiology*
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Molecular Sequence Data
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Phylogeny
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RNA, Ribosomal, 16S / classification
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Waste Disposal, Fluid / methods
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Water Pollutants, Chemical / metabolism*
Substances
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RNA, Ribosomal, 16S
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Water Pollutants, Chemical
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Ethanol
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Hydrogen
Associated data
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