title: Protozoan grazing reduces the current output of microbial fuel cells.
abstract: Several experiments were conducted to determine whether protozoan grazing can reduce current output from sediment microbial fuel cells. When marine sediments were amended with eukaryotic inhibitors, the power output from the fuel cells increased 2-5-fold. Quantitative PCR showed that Geobacteraceae sequences were 120 times more abundant on anodes from treated fuel cells compared to untreated fuel cells, and that Spirotrichea sequences in untreated fuel cells were 200 times more abundant on anode surfaces than in the surrounding sediments. Defined studies with current-producing biofilms of Geobacter sulfurreducens and pure cultures of protozoa demonstrated that protozoa that were effective in consuming G. sulfurreducens reduced current production up to 91% when added to G. sulfurreducens fuel cells. These results suggest that anode biofilms are an attractive food source for protozoa and that protozoan grazing can be an important factor limiting the current output of sediment microbial fuel cells.
authors.affiliation: Department of Microbiology, University of Massachusetts, Amherst, MA, United States; Department of Physical and Biological Sciences, Western New England University, Springfield, MA, United States. Electronic address: dholmes@microbio.umass.edu.
authors.forename: Dawn E
authors.initials: DE
authors.lastname: Holmes
authors.affiliation: Department of Microbiology, University of Massachusetts, Amherst, MA, United States.
authors.forename: Kelly P
authors.initials: KP
authors.lastname: Nevin
authors.affiliation: Department of Microbiology, University of Massachusetts, Amherst, MA, United States.
authors.forename: Oona L
authors.initials: OL
authors.lastname: Snoeyenbos-West
authors.affiliation: Department of Microbiology, University of Massachusetts, Amherst, MA, United States.
authors.forename: Trevor L
authors.initials: TL
authors.lastname: Woodard
authors.affiliation: Department of Microbiology, University of Massachusetts, Amherst, MA, United States.
authors.forename: Justin N
authors.initials: JN
authors.lastname: Strickland
authors.affiliation: Department of Microbiology, University of Massachusetts, Amherst, MA, United States.
authors.forename: Derek R
authors.initials: DR
authors.lastname: Lovley
mesh_terms: D001674:Bioelectric Energy Sources / Q000382:microbiology*; D018441:Biofilms; D004560:Electricity; D004566:Electrodes / Q000382:microbiology; D056890:Eukaryota / Q000502:physiology*; D045302:Geobacter / Q000502:physiology; D019015:Geologic Sediments / Q000382:microbiology
keywords: Anaerobic protozoa; Geobacteraceae; Sediment fuel cell