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Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) in offshore industries, such as the oil and gas pipelines, due to the high concentrations of sulfate in the seawater. SRM act upon the metal by the reactiveness of hydrogen sulfide (HS-), and by withdrawal of the available electrons (Fe --> Fe2+ + 2e-; E° = -0.47 V) in electrical contact with the metal (EMIC). However, methanogenic archaea can also cause MIC. Because they do not produce HS-, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood.
To investigate the corrosion potential of methanogens, we studied the EMIC methanogenic strains isolated from marine sediments (Methanobacterium-affiliated strain IM1) and crude oil tanks (Methanococcus maripaludis Mic1c10), in an in-house developed flow-through cell to simulate a fluctuating environment. A co-culture of M. maripaludis and D. alaskensis was also established to study the effect of syntrophic growth on metal corrosion that may occur in industrial pipelines. Results indicate that the rates of iron corrosion due to coupled methanogenesis (up to 0.4 mm/yr) are higher to that caused by the marine SRM Desulfovibrio alaskensis (0.15 mm/yr). Surface analyses of the metal showed severe pitting with high methane production. Genomic analysis of the EMIC methanogen M. maripaludis Mic1c10 will provide an insight on the mechanisms of MIC. Such knowledge and deeper understanding also from an electrokinetic point of view may not only provide further models in microbial electrophysiology, but also contribute to mitigation strategies in MIC
Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) in offshore industries, such as the oil and gas pipelines, due to the high concentrations of sulfate in the seawater. SRM act upon the metal by the reactiveness of hydrogen sulfide (HS-), and by withdrawal of the available electrons (Fe --> Fe2+ + 2e-; E° = -0.47 V) in electrical contact with the metal (EMIC). However, methanogenic archaea can also cause MIC. Because they do not produce HS-, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood.
To investigate the corrosion potential of methanogens, we studied the EMIC methanogenic strains isolated from marine sediments (Methanobacterium-affiliated strain IM1) and crude oil tanks (Methanococcus maripaludis Mic1c10), in an in-house developed flow-through cell to simulate a fluctuating environment. A co-culture of M. maripaludis and D. alaskensis was also established to study the effect of syntrophic growth on metal corrosion that may occur in industrial pipelines. Results indicate that the rates of iron corrosion due to coupled methanogenesis (up to 0.4 mm/yr) are higher to that caused by the marine SRM Desulfovibrio alaskensis (0.15 mm/yr). Surface analyses of the metal showed severe pitting with high methane production. Genomic analysis of the EMIC methanogen M. maripaludis Mic1c10 will provide an insight on the mechanisms of MIC. Such knowledge and deeper understanding also from an electrokinetic point of view may not only provide further models in microbial electrophysiology, but also contribute to mitigation strategies in MIC
Microbiologically Influenced Corrosion (MIC) is a phenomenon that is increasingly becoming a problem
for the society. MIC describes the negative effects a material can experience due to the presence of
microorganisms. In Europe, several research groups/ other industrial stakeholders are already dealing with
MIC. Unfortunately, the discussions are fragmented and the exchange of information is limited. A true
transdisciplinary approach is hardly ever experienced, although this would be logical for this
material/biology related challenge.
USA, Canada and Australia have strong networks, and develop methods, prevention measures and
standards, which Europe is forced to use, since nothing similar exists for a network and combined
knowledge to design them according to european standards. This makes Europe extremely dependent and,
in some cases, the potential measures or standards cannot been used because the suggested solutions
are prohibited by European laws (e.g. use of biocides).
Therefore, it is important to initiate a new European MIC-network. Europe needs to combine the efforts as
experts in different fields and develop prevention measures according to the European rules, in close
cooperation with industry and plant operators and owners of critical infrastructure. This COST Action will
provide the necessary interaction and communication, knowledge sharing, training of personnel and of
researchers of different disciplines. This will bring Europe to a leading role in this process, bringing ideas on
an equal level with other nations, considering the values which are important for Europe and attitudes (e.g.environmental protection) and representing greater protection for people, property and the environment.
The main aim and objective of the Action is to , in the context of MIC-research/control, encourage a
fluent/synergistic collaboration/communication, closing the gap between materials scientists, engineers,
microbiologists, chemists and integrity managers to encourage sufficient interaction between academia and
industry. This Action will create a common MIC-Network, including the important stakeholders.
As more industrial interests focusing on using salt caverns and repurposed gas or petroleum reservoirs for alternative fuel storage, i.e. CO2/H2, the question raises whether microorganisms may impact the infrastructure, gas purity and storage condition over time.
Environments with high salinity (> 1.5 Meq of NaCl) are resided by halophiles (salt-loving microorganisms). To compensate for the intensive osmotic stress, they have resorted to two main adaptation strategies: 1) production of compatible solutes and 2) accumulation of intracellular KCl. Microbial community analysis of several high salinity environments revealed a number of recurring genera, including Halomonas and Halanaerobium. However, the impact of halophiles on the overall integrity and stability of the storage facilities remain largely unknown.
To evaluate the suitability and stability of saline storage facilities, several model halophilic microorganisms, such as members of Halomonas, will be selected as testing subjects. First, the impact of halophiles on the infrastructure will be determined using an integrative approach by combining a number of techniques, including electrochemistry, TOF-SIMS, SEM/FIB/EDS and FIB-TEM. Second, the abilities of halophiles to alter the fuel composition (i.e. increase/decrease the fractions of H2) will be monitored using gas chromatography by growing them under high pressure.
As a result of climate change and the accompanying mandatory shift to renewable energy resources, microorganisms will continue to play an important role in the energy sector, both to their benefit and detriment. Thus, it is important to achieve a certain level of understanding regarding the activities and mechanisms of halophiles prior to large-scaled excursions.
Microbially influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) which act upon the metal by the reactiveness of hydrogen sulfide, and by withdrawal of the available electrons in electrical contact with the metal. Methanogenic archaea can also cause MIC by directly withdrawing electrons from the iron surface for methanogenesis. However, the mechanistic details and kinetics of the overall process are poorly understood. Precipitation of siderite, a by-product of methanogenesis, (4Fe + 5HCO3 + 5H+ 4FeCO3 + CH4 + 3H2O) can lead to an insulating layer on the metal surface and lower the corrosion rate. Still, the extent of FeCO3 precipitation may be significantly influenced by environmental conditions such as pH and advective processes.
Microbially influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) which act upon the metal by the reactiveness of hydrogen sulfide, and by withdrawal of the available electrons in electrical contact with the metal. Methanogenic archaea are supposed to cause MIC. Because they do not produce hydrogen sulfide, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood. Precipitation of siderite (4Fe + 5HCO3 + 5H+ 4FeCO3 + CH4 + 3H2O) can lead to an insulating layer on the metal surface and lower the corrosion rate. Still, the extent of FeCO3 precipitation may be significantly influenced by environmental conditions such as pH and advective processes.
Microbially influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) which act upon the metal by the reactiveness of hydrogen sulfide, and by withdrawal of the available electrons in electrical contact with the metal. Methanogenic archaea are supposed to cause MIC. Because they do not produce hydrogen sulfide, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood. Precipitation of siderite (4Fe + 5HCO3 + 5H+ 4FeCO3 + CH4 + 3H2O) can lead to an insulating layer on the metal surface and lower the corrosion rate. Still, the extent of FeCO3 precipitation may be significantly influenced by environmental conditions such as pH and advective processes.
Microbiologically influenced corrosion (MIC) is a phenomenon of increasing concern which affects various materials and sectors of society. MIC describes the effects, often negative, that a material can experience due to the presence of microorganisms. Unfortunately, although several research groups and industrial actors worldwide have already addressed MIC, discussions are fragmented, while information sharing and willingness to reach out to other disciplines is limited. A truly interdisciplinary approach, that would be logical for this material/biology/chemistry-related challenge, is rarely taken. In this review we highlight critical non-biological aspects of MIC that can sometimes be overlooked by microbiologists working on MIC but are highly relevant for an overall understanding of this phenomenon. Here, we identify gaps, methods and approaches to help solve MIC related challenges, with an emphasis on the MIC of metals. We also discuss the application of existing tools and approaches for managing MIC and propose ideas to promote an improved understanding of MIC. Furthermore, we highlight areas where the insights and expertise of microbiologists are needed to help progress this field.
Microbiologically influence corrosion (MIC) has become a big concern due the increased usage of different metals by our society. Microorganisms can use metal as an electron donor, causing unpredictable but serious damages. Nowadays it is known that besides sulfate reducing bacteria (SRB), other microorganisms including acetogens, iron oxidizers and methanogens can also induce MIC. Current studies related to methanogen-induced MIC (MI-MIC) mainly focused on environmental isolates from the oil and gas industry (e.g. Methanococcus maripaludis) with industrial materials e.g. iron. However, MI-MIC can occur in many other environments as well, including the oral cavity. Methanobrevibacter oralis is a methanogen isolated from the human oral cavity and was found more frequently in patients suffering from peri-implantitis/periodontitis. Titanium-implants removed from those patients have also showed clear signs of corrosion. The aim of our study is to establish and analyze corrosion potentials of dental metals (e.g. titanium) by oral methanogens. Periodontal pockets samples from patients suffering from periodontitis/peri-implantitis were taken for methanogenic and SRB enrichments. Stainless steel, pure titanium or Ti-6Al-4V alloy was used for corrosion studies. Corrosion rates and methane production were measured using weight-loss method and gas chromatography, respectively. Metal surfaces were visualized with scanning electron microscopy. Microbial communities in the dental pockets of healthy people and patients will be compared using 16S rRNA amplicon sequencing. Overall, this is the first study investigating the susceptibility of different dental implant materials to corrosion using human-related Archaea. The outcomes of this study can be further explored for a variety of clinical applications.
Since the early 19th century microorganisms were studied on their capabilities of causing microbiologically influenced corrosion (MIC) of metals. The most studied ones are sulfate-reducing bacteria (SRB), but others can corrode metals as well, e.g. acid-producing bacteria or methanogenic archaea (MA). However, these studies were mostly focused on metals related to the petroleum industry but metals for other industries, e.g. dentistry, are also susceptible to corrosion. The inert Titanium (Ti) is often used as an implant material, but it is a base metal. The formation of a passivating oxide layer allows Ti to be corrosion resistant at normal conditions.
Nonetheless, scanning electron microscope images on dental implants from patients with acute peri-implantitis showed clear signs of corrosion. Currently, the corrosion mechanism of dental implants is unknown, but many indications suggest that oral microorganisms, including MA (Methanobrevibacter oralis) and SRB (Desulfomicrobium orale), could be involved.
To determine if MA or SRB can corrode Ti (pure Ti or Ti-6Al-4V alloy), corrosion rate, methane and sulfide concentrations were analyzed. Electrical potential measurements using in-house developed electrochemical cells indicated a potential change on Ti in the presence of a corrosive MA strain compared to an abiotic control.
Microbial composition comparison will be analyzed using samples from dental pockets of 150 infected patients by considering the quality of the implant and 50 healthy people by means of amplicon sequencing. Enrichments and isolation of pure cultures from the dentals samples are also examined for their corrosion behavior. Overall, this is the first study investigating the susceptibility of dental implant material to corrosion using human related MA.
Pseudomonas fluorescens (Gram-negative) bacteria purchased from Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures were analyzed using high-resolution x-ray photoelectron spectroscopy at near ambient pressure conditions (NAP-XPS), 1500 Pa water vapor atmosphere. Fresh layers of P. fluorescence bacteria were grown on Luria Broth agar plates. Bacteria were taken from the agar plate with a sterile spatula and gently spread on a Si-wafer piece for NAP-XPS analysis. The NAP-XPS spectra of the bacterial envelope of P. fluorescence were obtained using monochromatic Al Kα radiation and include a survey scan and high-resolution spectra of C 1s, N 1s, P 2p, and O 1s as well. The presentation of the C 1s high-resolution spectrum includes the results of peak fitting analysis.
Surface characterisation of Escherichia coli under various conditions by near-ambient pressure XPS
(2018)
Bacteria are inherently in a hydrated state and therefore not compatible to ultra-high vacuum techniques such as XPS without prior sample preparation involving freeze drying or fast freezing.
This has changed with the development of near-ambient pressure (NAP)-XPS, which makes it possible to characterise the bacterial surface with minimal sample preparation. This paper presents NAP-XPS measurements of Escherichia coli under various NAP conditions: at 11 mbar in a humid environment, at 2 mbar after drying in the chamber, pre-dried at 4 mbar, and at 1 mbar after overnight pumping at 10^−4 mbar. The high-resolution spectra of carbon, nitrogen, and oxygen are presented and found to be in general agreement with XPS measurements from freeze-dried and fast-frozen bacteria. However, it was found that the amount of carbon components associated with polysaccharides increases relative to aliphatic carbon during drying and increases further after overnight pumping. This implies that drying has an impact on the bacterial surface.
This application note presents how EnviroESCA can be used to analyze E. coli biofilms on silicon under near ambient pressure conditions in various states of hydration. Such investigations of the outer bacterial cell surface in their hydrated state are essential for studying biological interfaces at work.
Bacteria generally interact with the environment via processes involving their cell-envelope. Thus, techniques that may shed light on their surface chemistry are attractive tools for providing an understanding of bacterial interactions. One of these tools is Al Kα-excited photoelectron spectroscopy (XPS) with its estimated information depth of <10 nm. XPS-analyses of bacteria have been performed for several decades on freeze-dried specimens in order to be compatible with the vacuum in the analysis chamber of the spectrometer. A limitation of these studies has been that the freeze-drying method may collapse cell structure as well as introduce surface contaminants. However, recent developments in XPS allow for analysis of biological samples at near ambient pressure (NAP-XPS) or as frozen hydrated specimens (cryo-XPS) in vacuum. In this work, we have analyzed bacterial samples from a reference strain of the Gram-negative bacterium Pseudomonas fluorescens using both techniques. We compare the results obtained and, in general, observe good agreement between the two techniques. Furthermore, we discuss advantages and disadvantages with the two analysis approaches and the output data they provide. XPS reference data from the bacterial strain are provided, and we propose that planktonic cells of this strain (DSM 50090) are used as a reference material for surface chemical analysis of bacterial systems.
Surface characterisation of biofilms by nearambient pressure X-ray photoelectron spectroscopy
(2018)
The XPS information depth of approximately 10 nm is in the same size range as the outer membrane of the gram-negative bacteria, which makes XPS a suitable tool for determining the elemental composition of the bacterial surface and monitor changes caused by outer stress like dehydration or exposure to antimicrobials. However, bacteria are inherently in a hydrated state, and therefore only compatible to ultra-high vacuum after extensive sample preparation, which may degrade the sample constituents. This issue is addressed by the development of near-ambient pressure (NAP)-XPS, which enables bacteria and biofilms to be characterised in their native wet state. Artificial biofilms, bacteria and biofilms of Escherichia coli have been characterised with the laboratory NAP-XPS instrument EnviroESCA from SPECS GmbH, at pressures ranging from high vacuum to 12 mbar, and in both humid and dry environment. By studying biological samples in their native wet state, new insight about composition and transport of drugs through cell membranes and the extracellular polymeric substance (EPS) of biofilms can be obtained.
The XPS information depth of approximately 10 nm is in the same size range as the outer membrane of the gram-negative bacteria, which makes XPS a suitable tool for determining the elemental composition of the bacterial surface and monitor changes caused by outer stress like dehydration or exposure to antimicrobials. However, bacteria are inherently in a hydrated state, and therefore only compatible to ultra-high vacuum after extensive sample preparation, which may degrade the sample constituents. This issue is addressed by the development of near-ambient pressure (NAP)-XPS, which enables bacteria and biofilms to be characterised in their native wet state. Artificial biofilms, bacteria and biofilms of Escherichia coli have been characterised with the laboratory NAP-XPS instrument EnviroESCA from SPECS GmbH, at pressures ranging from high vacuum to 12 mbar, and in both humid and dry environment. By studying biological samples in their native wet state, new insight about composition and transport of drugs through cell membranes and the extracellular polymeric substance (EPS) of biofilms can be obtained. In this contribution, the latest progress on biofilm characterisation by NAP-XPS will be presented, and measurement capabilities and limitations will be discussed.
A presentation held for the seminar "Ausgewählte analytische Methoden der Physik" hosted by Prof. Birgit Kanngießer at TU Berlin. The first part focus on depth-dependent XPS-measurements (XPS, synchrotron HAXPES) to obtain a concentration profile of iodine in an artificial biofilm. In the second part, NAP-XPS measurements of various bacterial samples are presented.
X-ray photoelectron spectroscopy (XPS) provides elemental and chemical information from the outermost ~10 nm of the sample surface. This is in the same order of magnitude as the thickness of the outer bacterial membrane of gram-negative bacteria, as well as outer membrane molecules as exopolysaccharides and lipopolysaccharides, commonly attached to the cell surface. With the development of near-ambient pressure (NAP)-XPS, bacteria can be analysed with minimal sample preparation.
EnviroESCA is a laboratory based NAP-XPS instrument, equipped with a monochromated Al Kα radiation source and a differentially pumped energy analyser connected to an exchangeable sample environment. It allows for measurements in various gas-atmospheres, including water vapor, which makes it possible to characterise bacteria and other biological samples close to their natural, hydrated state. Artificial model-biofilms of exopolysaccharides, planktonic Pseudomonas Fluorescens and biofilms of Escherichia Coli have been characterised in hydrated and dried state.
High-resolution XPS-spectra from carbon, oxygen, nitrogen and phosphorous can be assigned to carbohydrates, lipids and proteins in general agreement with literature. Especially the carbon 1s peak is of interest. A series of measurements of an E. coli biofilm from 11 mbar in humid environment to 1 mbar air reveal changes in the C1s peak, which suggests that the bacterial surface undergo substantial Change.