We evaluated the consumption of hydrogen gas at the anode of a microbial electrolysis cell (MEC) and characterized the significance of new interactions between anode respiring bacteria (ARB) and homo-acetogens. We demonstrated the significance of biofilm limitation for direct consumption of H2 over acetate by ARB, using the deep biofilm model. Selective inhibition of the major competing hydrogen sink at the biofilm anode, methanogenesis, resulted in significant increase in electron recovery as electric current (∼10–12 A/m2). The presence of acetate at high concentration in the anode compartment and detection of formate, a known intermediate of the acetyl-CoA pathway, provide evidence towards the role of homoacetogenic bacteria. We also assessed the activity of homoacetogens with reverse transcription quantitative PCR targeting formyltetrahydrofolate synthetase (FTHFS) transcripts, and observed a comparable decrease in the FTHFS transcript numbers with current density and acetate concentrations as we decreased the HRT below 4.5 h. The biofilm anode community was predominated by Deltaproteobacteria (70% of total readouts) along with a fraction of the homoacetogenic genus, Acetobacterium (4% of total readouts), established by pyrosequencing targeting the V6 region of the 16S rRNA. Homoacetogens seem to play a major role as syntrophic members of the biofilm anode community when electron recovery is high.
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Research Article|
January 01 2012
The role of homoacetogenic bacteria as efficient hydrogen scavengers in microbial electrochemical cells (MXCs) Available to Purchase
Prathap Parameswaran;
1Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, Tempe, AZ 85287-5701, USA
E-mail: [email protected]
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César I. Torres;
César I. Torres
1Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, Tempe, AZ 85287-5701, USA
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Dae-Wook Kang;
Dae-Wook Kang
1Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, Tempe, AZ 85287-5701, USA
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Bruce E. Rittmann;
Bruce E. Rittmann
1Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, Tempe, AZ 85287-5701, USA
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Rosa Krajmalnik-Brown
Rosa Krajmalnik-Brown
1Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, Tempe, AZ 85287-5701, USA
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Water Sci Technol (2012) 65 (1): 1–6.
Article history
Received:
October 21 2010
Accepted:
January 10 2011
Citation
Prathap Parameswaran, César I. Torres, Dae-Wook Kang, Bruce E. Rittmann, Rosa Krajmalnik-Brown; The role of homoacetogenic bacteria as efficient hydrogen scavengers in microbial electrochemical cells (MXCs). Water Sci Technol 1 January 2012; 65 (1): 1–6. doi: https://doi.org/10.2166/wst.2011.519
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