title: Abundance of the multiheme c-type cytochrome OmcB increases in outer biofilm layers of electrode-grown Geobacter sulfurreducens.
abstract: When Geobacter sulfurreducens utilizes an electrode as its electron acceptor, cells embed themselves in a conductive biofilm tens of microns thick. While environmental conditions such as pH or redox potential have been shown to change close to the electrode, less is known about the response of G. sulfurreducens to growth in this biofilm environment. To investigate whether respiratory protein abundance varies with distance from the electrode, antibodies against an outer membrane multiheme cytochrome (OmcB) and cytoplasmic acetate kinase (AckA) were used to determine protein localization in slices spanning ∼25 µm-thick G. sulfurreducens biofilms growing on polished electrodes poised at +0.24 V (vs. Standard Hydrogen Electrode). Slices were immunogold labeled post-fixing, imaged via transmission electron microscopy, and digitally reassembled to create continuous images allowing subcellular location and abundance per cell to be quantified across an entire biofilm. OmcB was predominantly localized on cell membranes, and 3.6-fold more OmcB was detected on cells 10-20 µm distant from the electrode surface compared to inner layers (0-10 µm). In contrast, acetate kinase remained constant throughout the biofilm, and was always associated with the cell interior. This method for detecting proteins in intact conductive biofilms supports a model where the utilization of redox proteins changes with depth.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America.
authors.forename: Camille S
authors.initials: CS
authors.lastname: Stephen
authors.affiliation: BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, United States of America.
authors.forename: Edward V
authors.initials: EV
authors.lastname: LaBelle
authors.affiliation: Department of Geosciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Brantley
authors.affiliation: BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, United States of America; Department of Microbiology, University of Minnesota, St. Paul, Minnesota, United States of America.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Bond
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D001674:Bioelectric Energy Sources; D018441:Biofilms / Q000254:growth & development*; D004566:Electrodes; D004579:Electron Transport; D045302:Geobacter / Q000235:genetics*; D010084:Oxidation-Reduction
chemical_list: D001425:Bacterial Outer Membrane Proteins; C436968:OmcB protein, bacteria
references.citation: J Bacteriol. 2003 Apr;185(7):2096-103
references.pmid: 12644478
references.citation: Biochemistry. 2012 Apr 3;51(13):2747-56
references.pmid: 22417533
references.citation: J Bacteriol. 1998 Feb;180(3):505-13
references.pmid: 9457851
references.citation: J Bacteriol. 1996 May;178(9):2479-88
references.pmid: 8626312
references.citation: Biochem Biophys Res Commun. 1995 Nov 22;216(3):1013-7
references.pmid: 7488173
references.citation: Biochem J. 2001 Oct 1;359(Pt 1):147-52
references.pmid: 11563978
references.citation: Chemphyschem. 2011 Aug 22;12(12):2235-41
references.pmid: 21671335
references.citation: Biotechnol Bioeng. 2008 Aug 1;100(5):872-81
references.pmid: 18551519
references.citation: Environ Sci Technol. 2008 Dec 1;42(23):8773-7
references.pmid: 19192796
references.citation: J Bacteriol. 2005 Jul;187(13):4505-13
references.pmid: 15968061
references.citation: Appl Environ Microbiol. 2003 Mar;69(3):1548-55
references.pmid: 12620842
references.citation: J Bacteriol. 2004 Jun;186(12):4042-5
references.pmid: 15175321
references.citation: Microbiol Rev. 1991 Jun;55(2):259-87
references.pmid: 1886521
references.citation: ChemSusChem. 2012 Jun;5(6):1106-18
references.pmid: 22581467
references.citation: Biotechnol Bioeng. 2008 Dec 15;101(6):1214-22
references.pmid: 18980182
references.citation: Anal Biochem. 1976 May 7;72:248-54
references.pmid: 942051
references.citation: Appl Environ Microbiol. 2008 Dec;74(23):7348-55
references.pmid: 18836002
references.citation: Biotechnol Bioeng. 2012 Oct;109(10):2651-62
references.pmid: 22549331
references.citation: Science. 2002 May 10;296(5570):1066-8
references.pmid: 12004117
references.citation: J Bacteriol. 2011 Mar;193(5):1023-33
references.pmid: 21169487
references.citation: FEMS Microbiol Lett. 2000 Apr 15;185(2):205-11
references.pmid: 10754249
references.citation: Appl Microbiol Biotechnol. 2012 Jan;93(1):41-8
references.pmid: 22072194
references.citation: Trends Ecol Evol. 1993 Jun;8(6):213-7
references.pmid: 21236151
references.citation: J Bacteriol. 2009 Sep;191(18):5669-79
references.pmid: 19592588
references.citation: Microbiology (Reading). 2005 Jun;151(Pt 6):1761-1767
references.pmid: 15941985
references.citation: BMC Microbiol. 2007 Mar 08;7:16
references.pmid: 17346345
references.citation: Appl Environ Microbiol. 2004 Sep;70(9):5183-9
references.pmid: 15345398
references.citation: ISME J. 2010 Apr;4(4):509-19
references.pmid: 20033069
references.citation: PLoS One. 2009 May 20;4(5):e5628
references.pmid: 19461962
references.citation: Biochem J. 2003 Jan 1;369(Pt 1):153-61
references.pmid: 12356333
references.citation: ChemSusChem. 2012 Jun;5(6):1047-53
references.pmid: 22577055
references.citation: J Bacteriol. 2008 May;190(10):3670-80
references.pmid: 18359807
references.citation: Environ Sci Technol. 2008 Apr 15;42(8):2999-3004
references.pmid: 18497157
references.citation: Bioelectrochemistry. 2008 Jun;73(1):70-5
references.pmid: 18538641
references.citation: Biochim Biophys Acta. 2006 Jul;1764(7):1198-206
references.pmid: 16797259
references.citation: Funct Integr Genomics. 2007 Jul;7(3):229-55
references.pmid: 17406915
references.citation: Proc Natl Acad Sci U S A. 2012 Sep 18;109(38):15467-72
references.pmid: 22955881
references.citation: mBio. 2013 Jan 15;4(1):
references.pmid: 23322638
references.citation: Appl Environ Microbiol. 1994 Oct;60(10):3752-9
references.pmid: 7527204
references.citation: Appl Environ Microbiol. 2007 Sep;73(18):5797-808
references.pmid: 17675441
references.citation: Appl Environ Microbiol. 2010 Jun;76(12):3999-4007
references.pmid: 20400562
references.citation: J Bacteriol. 2006 Dec;188(24):8469-78
references.pmid: 17041036
references.citation: J Bacteriol. 2004 Aug;186(16):5543-6
references.pmid: 15292160
references.citation: J Bacteriol. 1990 Apr;172(4):2150-9
references.pmid: 2108132
references.citation: Biochem Biophys Res Commun. 1998 Oct 29;251(3):744-7
references.pmid: 9790980
references.citation: Mol Microbiol. 2010 Oct;78(2):519-32
references.pmid: 20807196
references.citation: Biochim Biophys Acta. 2008 Dec;1784(12):1935-41
references.pmid: 18638577
references.citation: ChemSusChem. 2012 Jun;5(6):1092-8
references.pmid: 22577044
references.citation: Angew Chem Int Ed Engl. 2013 Jan 14;52(3):925-8
references.pmid: 23184838
references.citation: Appl Environ Microbiol. 2008 Feb;74(3):615-23
references.pmid: 18065612
references.citation: Environ Microbiol Rep. 2011 Apr;3(2):211-7
references.pmid: 23761253
references.citation: ChemSusChem. 2012 Jun;5(6):1099-105
references.pmid: 22615023
references.citation: FEMS Microbiol Lett. 2008 Sep;286(1):39-44
references.pmid: 18616590
references.citation: J Ind Microbiol. 1995 Feb;14(2):85-93
references.pmid: 7766214
references.citation: Appl Environ Microbiol. 2008 Dec;74(23):7329-37
references.pmid: 18849456
references.citation: FEMS Microbiol Rev. 2010 Jan;34(1):3-17
references.pmid: 19895647
references.citation: J Bacteriol. 2006 Apr;188(8):2792-800
references.pmid: 16585740
references.citation: J Bacteriol. 2009 Jul;191(13):4207-17
references.pmid: 19395486
references.citation: Environ Microbiol. 2006 Oct;8(10):1805-15
references.pmid: 16958761
references.citation: J Bacteriol. 2006 Apr;188(8):3138-42
references.pmid: 16585776
references.citation: Gene. 2006 Dec 15;384:73-95
references.pmid: 17014972
references.citation: FEMS Microbiol Lett. 2007 Dec;277(1):21-7
references.pmid: 17986080
references.citation: J Biol Chem. 1951 Nov;193(1):265-75
references.pmid: 14907713
references.citation: Microb Cell Fact. 2010 Nov 22;9:90
references.pmid: 21092215
references.citation: Appl Environ Microbiol. 2005 Dec;71(12):8634-41
references.pmid: 16332857