TY - CONF A1 - Wurzler, Nina A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Kunte, Hans-Jörg A1 - Özcan Sandikcioglu, Özlem T1 - Chemical interaction mechanisms of metal reducing bacteria on steel surfaces N2 - Metal reducing bacteria (MRB) are able to utilize various materials such as iron, uranium and manganese as well as many organic compounds as electron acceptors. This process leads to the conversion of Fe(III) containing passive film species to soluble Fe(II) oxides and hydroxides. The reduction process triggers the acceleration of general and local corrosion processes. Electron transfer mechanisms are not yet fully understood. In literature it has been controversially discussed to which extend secreted electron shuttles contribute to the extracellular electron transfer (EET). To understand the chemical and electrochemical interaction mechanisms of MRB with steel surfaces this project combines a variety of in-situ techniques. The changes in oxide chemistry on Fe/steel surfaces in the presence of biomolecules and MRB are under investigation using a newly designed electrochemical cell for in situ XANES (x-ray absorption near edge structure) spectroscopy. Electrochemical quartz crystal microbalance (eQCM) studies support the spectroscopic investigations to gain information about the kinetics of attachment processes and changes in biofilm viscosity. The biofilm structure and composition as well as cell viability are investigated by complementary ex situ spectroscopic and microscopic analysis. Combining spectroscopic techniques and eQCM data with electrochemical measurements, biological processes and the resulting degradation of steel surfaces can be observed in a non-destructive manner. Selecting model systems and a defined biological medium allows the determination of individual effects of diverse surface and environmental parameters. The fundamental understanding of bacterial attachment mechanisms and initial steps of biofilm formation will contribute to the development of new antifouling strategies. T2 - 12th International Conference on Biology and Synchrotron Radiation CY - San Francisco, CA, USA DA - 21.08.2016 KW - Microbially influenced corrosion (MIC) KW - Metal reducing bacteria KW - XANES KW - Electrochemistry PY - 2016 AN - OPUS4-37238 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wurzler, Nina A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Kunte, Hans-Jörg A1 - Özcan Sandikcioglu, Özlem T1 - Investigation of the mechanisms of microbially induced corrosion on Fe/steel surfaces N2 - The role of metal reducing bacteria (MRB) in corrosion is being controversially discussed in the literature. They can utilize metals including iron, uranium and manganese as well as many organic compounds as electron acceptors. The reduction of Fe(III) compounds to soluble Fe(II) species leads to the destruction of passive films on steel, resulting in acceleration of general and local corrosion processes. Recent research shows that the secretion of electron shuttles like riboflavins also contribute to the extracellular electron transfer (EET). The aim of this project is to understand the chemical and electrochemical interaction mechanisms of MRB with steel surfaces by means of combined in situ techniques. An electrochemical XANES (x-ray absorption near edge spectroscopy) cell has been designed to study the changes of passive film chemistry in the presence of biomolecules and MRB. Electrochemical quartz crystal microbalance (eQCM) is used for studying the kinetics of bacterial cell attachment and diffusion of biomolecules in model biofilms. In situ investigations are complemented by ex situ spectroscopic and microscopic analysis to investigate the biofilm structure, composition and cell viability. Via the combination of electrochemical methods with spectroscopic techniques and QCM we are able to follow biological processes and resulting degradation of steel surfaces in a non-destructive manner. The selection of model systems and a defined biological medium allows the identification of the effects of individual surface and environmental parameters. The fundamental understanding of bacterial attachment mechanisms and initial steps of biofilm formation will contribute to the development of new antifouling strategies. T2 - Electrochemistry 2016 CY - Goslar, Germany DA - 26.09.2016 KW - MIC KW - Microbiologically influenced corrosion KW - XANES KW - Electrochemistry PY - 2016 AN - OPUS4-38199 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wurzler, Nina A1 - Wagner, Ralph A1 - Schutter, Jan David A1 - Das, Chayanika A1 - Dimper, Matthias A1 - An, Biwen A1 - Koerdt, Andrea A1 - Lützenkirchen-Hecht, Dirk A1 - Özcan Sandikcioglu, Özlem T1 - Effect of cultivation conditions on the electrochemical activity of metal reducing bacteria (mrb) on stainless steel surfaces N2 - Investigation of the electrochemical activity of two cultures grown with and without abundance of Fe(III) and their different ability to reduce and therefore dissolve iron oxides in steel and model iron thin films. T2 - Eurocorr2019 CY - Sevilla, Spain DA - 09.09.2019 KW - X-ray spectroscopic techniques KW - Microbiologically influenced corrosion KW - MIC KW - XANES KW - Metal reducing bacteria KW - In situ PY - 2019 AN - OPUS4-49692 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wurzler, Nina A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Kunte, Hans-Jörg A1 - Özcan Sandikcioglu, Özlem T1 - Changes in the passive film chemistry on stainless steels during microbiologically influenced corrosion: A combined electrochemistry and XANES study N2 - Metal reducing bacteria (MRB) are capable of utilizing different metals, such as iron, chromium, manganese or uranium as well as many organic compounds, as electron acceptors for their metabolism. Via direct and indirect electron transfer processes MRB are able to convert insoluble passive film species like Fe(III)-oxides to soluble Fe(II)-oxides and hydroxides. This weakening of the passive film not only leads to an acceleration of the general corrosion processes, but also increases the susceptibility of stainless steels to pitting corrosion. Electron transfer mechanisms are not yet fully understood and the role of bacteria in corrosion processes is controversially discussed in the literature. Moreover, recent research indicates that the secretion of electron shuttles like riboflavins by MRB also contributes to the extracellular electron transfer. This project aims at clarifying the chemical and electrochemical interaction mechanisms of MRB with stainless steel surfaces. To investigate the changes in the oxide chemistry on the stainless steel surface in the presence of biomolecules and MRB a new flow cell has been designed and constructed which enables the collection of XANES (X-ray Absorption Near Edge Structure) spectra in fluorescence mode at the Fe K-edge and electrochemical analysis. Availability of oxygen and the pre-exposure of the MRB to Fe(III) during cultivation have been investigated as parameters with significant effect on the corrosion rates. XANES analysis is supplemented by ex-situ X-Ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRRAS) to complete the surface characterisation in terms of the oxide chemistry and the composition of organic residues. Complementary electrochemical quartz crystal microbalance (e-QCM) measurements have been performed to quantify the kinetics of bacterial attachment and biofilm formation. Together with the frequency shift, the evolution of the dissipation signal has been analyzed to investigate the changes in viscosity and structure of the biofilm from initial stages up to maturation. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) has been used to study the structure and viscoelastic properties of the biofilms after e-QCM experiments. The presentation will summarize our results on the effects of individual surface and environment related parameters on the chemical/electrochemical interaction mechanisms of MRB leading to passive film degradation on stainless steel surfaces and provide useful insights from a fundamental aspect for the development of novel mitigation strategies for microbiologically influenced corrosion. T2 - EUROCORR 2017 & 20thICC CY - Prague, Czech Republic DA - 04.09.2017 KW - Microbiologically influenced corrosion (MIC) KW - XANES KW - Stainless steel KW - Corrosion PY - 2017 AN - OPUS4-43407 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -