title: Use of SWATH mass spectrometry for quantitative proteomic investigation of Shewanella oneidensis MR-1 biofilms grown on graphite cloth electrodes.
abstract: Quantitative proteomics from low biomass, biofilm samples is not well documented. In this study we show successful use of SWATH-MS for quantitative proteomic analysis of a microbial electrochemically active biofilm. Shewanella oneidensis MR-1 was grown on carbon cloth electrodes under continuous anodic electrochemical polarizations in a bioelectrochemical system (BES). Using lactate as the electron donor, anodes serving as terminal microbial electron acceptors were operated at three different electrode potentials (+0.71 V, +0.21 V & -0.19 V vs. SHE) and the development of catalytic activity was monitored by measuring the current traces over time. Once maximum current was reached (usually within 21-29 h) the electrochemical systems were shut off and biofilm proteins were extracted from the electrodes for proteomic assessment. SWATH-MS analysis identified 704 proteins, and quantitative comparison was made of those associated with tricarboxcylic acid (TCA) cycle. Metabolic differences detected between the biofilms suggested a branching of the S. oneidensis TCA cycle when grown at the different electrode potentials. In addition, the higher abundance of enzymes involved in the TCA cycle at higher potential indicates an increase in metabolic activity, which is expected given the assumed higher energy gains. This study demonstrates high numbers of identifications on BES biofilm samples can be achieved in comparison to what is currently reported. This is most likely due to the minimal preparation steps required for SWATH-MS.
authors.affiliation: The University of Queensland, Advanced Water Management Centre, St. Lucia, QLD 4072, Australia. Electronic address: c.grobbler@uq.edu.au.
authors.forename: Christy
authors.initials: C
authors.lastname: Grobbler
authors.affiliation: The University of Queensland, Centre for Microbial Electrosynthesis, St. Lucia, QLD 4072, Australia.
authors.forename: Bernardino
authors.initials: B
authors.lastname: Virdis
authors.affiliation: The University of Queensland, School of Chemical and Molecular Biosciences, St. Lucia, QLD 4072, Australia.
authors.forename: Amanda
authors.initials: A
authors.lastname: Nouwens
authors.affiliation: Department of Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Harnisch
authors.affiliation: Laboratory of Microbial Ecology and Technology, Faculty of Bioscience Engineering, Coupure Links 653, B-9000 Ghent, Belgium.
authors.forename: Korneel
authors.initials: K
authors.lastname: Rabaey
authors.affiliation: The University of Queensland, Advanced Water Management Centre, St. Lucia, QLD 4072, Australia; The University of Queensland, School of Chemical and Molecular Biosciences, St. Lucia, QLD 4072, Australia. Electronic address: phil.bond@awmc.uq.edu.au.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Bond
mesh_terms: D001674:Bioelectric Energy Sources; D018441:Biofilms / Q000254:growth & development*; D004560:Electricity; D004566:Electrodes / Q000382:microbiology*; D004579:Electron Transport; D006108:Graphite; D007773:Lactates / Q000378:metabolism; D013058:Mass Spectrometry; D053858:Metabolic Networks and Pathways; D020543:Proteome / Q000032:analysis*; D040901:Proteomics; D020592:Shewanella / Q000737:chemistry* / Q000502:physiology*
chemical_list: D007773:Lactates; D020543:Proteome; D006108:Graphite
keywords: Bioelectrochemical system; Electroactive biofilms; Proteomics; SWATH-MS; Shewanella oneidensis MR1