title: Changes in protein expression across laboratory and field experiments in Geobacter bemidjiensis.
abstract: Bacterial extracellular metal respiration, as carried out by members of the genus Geobacter, is of interest for applications including microbial fuel cells and bioremediation. Geobacter bemidjiensis is the major species whose growth is stimulated during groundwater amendment with acetate. We have carried out label-free proteomics studies of G. bemidjiensis grown with acetate as the electron donor and either fumarate, ferric citrate, or one of two hydrous ferric oxide mineral types as electron acceptor. The major class of proteins whose expression changes across these conditions is c-type cytochromes, many of which are known to be involved in extracellular metal reduction in other, better-characterized Geobacter species. Some proteins with multiple homologues in G. bemidjiensis (OmcS, OmcB) had different expression patterns than observed for their G. sulfurreducens homologues under similar growth conditions. We also compared the proteome from our study to a prior proteomics study of biomass recovered from an aquifer in Colorado, where the microbial community was dominated by strains closely related to G. bemidjiensis. We detected an increased number of proteins with functions related to motility and chemotaxis in the Colorado field samples compared to the laboratory samples, suggesting the importance of motility for in situ extracellular metal respiration.
authors.affiliation: Signature Sciences and Technology Division, and ‡Biological Sciences Division, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Merkley
authors.forename: Kelly C
authors.initials: KC
authors.lastname: Wrighton
authors.forename: Cindy J
authors.initials: CJ
authors.lastname: Castelle
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Anderson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wilkins
authors.forename: Vega
authors.initials: V
authors.lastname: Shah
authors.forename: Tyler
authors.initials: T
authors.lastname: Arbour
authors.forename: Joseph N
authors.initials: JN
authors.lastname: Brown
authors.forename: Steven W
authors.initials: SW
authors.lastname: Singer
authors.forename: Richard D
authors.initials: RD
authors.lastname: Smith
authors.forename: Mary S
authors.initials: MS
authors.lastname: Lipton
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D018533:Biomass; D002853:Chromatography, Liquid; D045302:Geobacter / Q000378:metabolism*; D060587:Groundwater / Q000382:microbiology; D016014:Linear Models; D053719:Tandem Mass Spectrometry
chemical_list: D001426:Bacterial Proteins
keywords: Geobacter bemidjiensis; c-type cytochromes; electron acceptors; proteomics