title: Hydrogen consumption in microbial electrochemical systems (MXCs): the role of homo-acetogenic bacteria.
abstract: Homo-acetogens in the anode of a microbial electrolysis cell (MEC) fed with H(2) as sole electron donor allowed current densities similar to acetate-fed biofilm anodes (∼10 A/m(2)). Evidence for homo-acetogens included accumulation of acetate at high concentrations (up to 18 mM) in the anode compartment; detection of formate, a known intermediate during reductive acetogenesis by the acetyl-CoA pathway; and detection of formyl tetrahydrofolate synthetase (FTHFS) genes by quantitative real-time PCR. Current production and acetate accumulation increased in parallel in batch and continuous mode, while both values decreased simultaneously at short hydraulic retention times (1h) in the anode compartment, which limited suspended homo-acetogens. Acetate produced by homo-acetogens accounted for about 88% of the current density of 10A/m(2), but the current density was sustained at 4A/m(2) at short hydraulic retention time because of a robust partnership of homo-acetogens and anode respiring bacteria (ARB) in the biofilm anode.
authors.affiliation: Center for Environmental Biotechnology, The Biodesign Institute at Arizona State University, PO Box 875701, Tempe, AZ 85287-5701, USA. prathap@asu.edu
authors.forename: Prathap
authors.initials: P
authors.lastname: Parameswaran
authors.forename: César I
authors.initials: CI
authors.lastname: Torres
authors.forename: Hyung-Sool
authors.initials: HS
authors.lastname: Lee
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Rittmann
authors.forename: Rosa
authors.initials: R
authors.lastname: Krajmalnik-Brown
mesh_terms: D000085:Acetates / Q000378:metabolism; D000105:Acetyl Coenzyme A / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism*; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D018441:Biofilms / Q000254:growth & development; D019069:Cell Respiration; D004560:Electricity; D004566:Electrodes / Q000382:microbiology; D004572:Electrolysis; D005574:Formate-Tetrahydrofolate Ligase / Q000235:genetics / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D000085:Acetates; D000105:Acetyl Coenzyme A; D006859:Hydrogen; D005574:Formate-Tetrahydrofolate Ligase