4 Material und Umwelt
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Organisationseinheit der BAM
- 4.1 Biologische Materialschädigung und Referenzorganismen (55) (entfernen)
Eingeladener Vortrag
- nein (15)
Microbiologically influenced corrosion (MIC) is the deterioration of metals due to the metabolic activities of microorganisms. Microorganisms can take electrons directly from the metal surface (EMIC) thereby causing corrosion. Well known culprits of EMIC are: sulfate-reducing bacteria (SRB), acetogens and methanogens.
Our aims
- Develop a novel flow system to study MIC by methanogens to mimic industrial Environments
- Investigate the inhibitory concentrations of biocides targeting SRB on corrosive methanogenic strains
- Investigate the inhibitory effects of corrosion inhibitors on methanogens
- Compare the inhibitory concentrations to SRB
Microbiologically influenced corrosion (MIC) is an expensive but unpredictable problem for the industries. The most well-known culprit for MIC is the sulfate-reducing microorganisms (SRM), such as members from the genus Desulfovibrio. It has been widely accepted that SRM can contribute significantly to MIC through the production of hydrogen sulfide (HS-) or in some cases a direct electron uptake from the metal surface. However, in a real environmental system, SRM is not exclusive and often involved with other microorganisms that may also contribute to MIC, such as methanogens.
Methanogenic archaea can produce methane (CH4) using H2+CO2, formate, methylated amines or acetate. Methanogens are highly abundant in the environment and many are found in very extreme conditions, such as high temperature and high salinity. Previous researches have demonstrated that methanogens are capable of MIC, though the specific mechanisms are still under investigation. In the oil and gas industry, methanogens are not considered as the main contributor for MIC since the corrosion rates are often too low. However, the tests for methanogen-induced MIC are usually performed at static conditions, which cannot represent the system accurately. Here, we developed a novel anaerobic system to evaluate the corrosion potential of methanogens under flow conditions. We will use the Methanococcus maripaludis KA1 strain, which was isolated from a crude oil tank, as the organism of interest. A separate system for Desulfovibrio alaskensis will be established for corrosion rate comparisons. Furthermore, we will study the synergistic effects of M. maripaludis and D. alaskensis on MIC under flow.
Zearalenone (ZEN) and its phase II sulfate and glucoside metabolites have been detected in food and feed commodities. After consumption, the conjugates can be hydrolyzed by the human intestinal microbiota leading to liberation of ZEN that implies an underestimation of the true ZEN exposure. To include ZEN conjugates in routine analysis, reliable standards are needed, which are currently not available. Thus, the aim of the present study was to develop a facilitated biosynthesis of ZEN-14-sulfate, ZEN-14-glucoside and ZEN-16-glucoside. A metabolite screening was conducted by adding ZEN to liquid fungi cultures of known ZEN conjugating Aspergillus and Rhizopus strains. Cultivation conditions and ZEN incubation time were varied. All media samples were analyzed for metabolite formation by HPLC-MS/MS. In addition, a consecutive biosynthesis was developed by using Fusarium graminearum for ZEN biosynthesis with subsequent conjugation of the toxin by utilizing Aspergillus and Rhizopus species. ZEN-14-sulfate (yield: 49%) is exclusively formed by Aspergillus oryzae. ZEN-14-glucoside (yield: 67%) and ZEN-16-glucoside (yield: 39%) are formed by Rhizopus oryzae and Rhizopus oligosporus, respectively. Purities of ≥73% ZEN-14-sulfate, ≥82% ZEN-14-glucoside and ≥50% ZEN-16-glucoside were obtained by 1H-NMR. In total, under optimized cultivation conditions, fungi can be easily utilized for a targeted and regioselective synthesis of ZEN conjugates.
This application note presents how EnviroESCA can be used to analyze bacterial samples under near ambient pressure conditions in various states of hydration using different levels of humidity. Such investigations of bacterial cell wall surfaces in their hydrated state are essential for studying biological interfaces at work.
The use of innovative near-ambient pressure (NAP-)XPS instrumentation allows the detailed analysis of irregularly-surfaced biofilms. NAP-XPS enables the surface analysis of bacterial samples in their natural hydrated state without complex sample preparation techniques such as freeze-drying or fast-freezing, which are needed for XPS analysis in ultrahigh vacuum.
The first documentation of fuel biodeterioration dates back to the late 19th century. However, extensive studies concerning the microbial fuel contamination started in 1980’s. Polymeric fuel storage tanks containing diesel and biodiesel provide environmental conditions for microbial growth. Several studies demonstrated that bacteria, which were found in contaminated fuel systems, can use fuels as macronutrient; but such bacteria can also cause microbiologically influenced corrosion and fouling.
The aim of this study is to investigate the initial attachment behavior of bacteria, isolated from a diesel contamination, on neat and photooxidized high-density polyethylene (PE-HD). Two common PE-HD’s, less- and biodiesel-stabilized, were radiated to UV light representing a tank exposed to sunlight. The effect of photooxidiation on PE-HD’s surface were characterized chemically by Fourier-transform infrared spectroscopy (FTIR). The attached bacteria Pseudomonas aeruginosa and Bacillus subtilis on the polymer surface were evaluated by fluorescence microscopy and colony-forming unit tests (CFU).
ABSTRACT: A collection of thioimidazolium salts were synthesized and used as a new class of nonvolatile alkylating agents. Their nonvolatility prevents exposure during use or handling and are thus drastically safer than conventional alkylating agents. We discovered that thioimidazolium Iodide salts cannot release volatile compounds in the solid state, but instead only decompose when molten. Since decomposition proceeds via alkyl iodide elimination, SN2 of iodide on the thioimidazolium cation is constrained in the solid state, and instead can occur only upon melting when ions are mobile. By smart design of these alkylators, the melting point and thus the decomposition temperature of these salts can be increased from 106 to 169 °C and release negligible volatile organic compounds prior to melting. Thioimidazolium-bis(trifluoromethanesulfonyl)imide (TFSI) ionic liquids act as a completely nonvolatile and air-stable TFSI-based alkylating agent and can be used for high-throughput Synthesis of TFSI ionic liquids without solvent. Alkyl groups from methyl to dodecyl can be transferred to a nucleophile and the product purified by sublimation of the thione byproduct, which can then be recycled. We also found that thioimidazolium salts with a dodecyl chain are bactericidal, yet can hydrolyze in water to form benign neutral products, and thus wont accumulate in the environment. These results demonstrate that thioimidazolium salts are a designable platform for the pursuit of safer and more environmentally friendly alkylating and antiseptic agents.
The importance of soldiers to termite Society defence has long been recognized, but the contribution of soldiers to other societal functions, such as colony immunity, is less well understood.
We explore this issue by examining the role of soldiers in protecting nestmates against pathogen infection. Even though they are unable to engage in grooming behaviour, we find that the presence of soldiers of the Darwin termite, Mastotermes darwiniensis, significantly improves the survival of nestmates following entomopathogenic infection.
We also show that the copious exocrine oral secretions produced by Darwin termite soldiers contain a high concentration of Proteins involved in digestion, chemical biosynthesis, and immunity. The oral secretions produced by soldiers are sufficient to protect nestmates against infection, and they have potent inhibitory activity against a broad spectrum of microbes. Our findings support the view that soldiers may play an important role in colony immunity, and broaden our understanding of the possible function of soldiers during the origin of soldier-first societies.
Chemical-free pest control by dielectric
heating with radio waves and microwaves:
Thermal effects
(2018)
Thermal pest control with hot air is widely accepted as an alternative to chemical methods. However, it requires relatively long treatment times owing to the low thermal conductivity of wood. Direct dielectric heating that applies radio waves or microwaves has the advantage of more homogeneous heating. However, Sound experimental data on this technique are currently rare. Therefore, the thermal treatment of wood-destroying insects with radio waves and microwaves was studied with two model pests, Anobium punctatum and Hylotrupes bajulus, and with Tenebrio molitor as a reference. The secure elimination of pests was achieved, and the corresponding treatment time was in the range of a few minutes. Temperature profiles were more homogeneous when applying radio waves.
Bioinformatics meets virology: The European virus bioinformatics center's second annual meeting
(2018)
The Second Annual Meeting of the European Virus Bioinformatics Center (EVBC), held in Utrecht, Netherlands, focused on computational approaches in virology, with topics including (but not limited to) virus discovery, diagnostics, (meta-)genomics, modeling, epidemiology, molecular structure, evolution, and viral ecology. The goals of the Second Annual Meeting were threefold: (i) to bring together virologists and bioinformaticians from across the academic, industrial, professional, and training sectors to share best practice; (ii) to provide a meaningful and interactive scientific environment to promote discussion and collaboration between students, postdoctoral fellows, and both new and established investigators; (iii) to inspire and suggest new research directions and questions. Approximately 120 researchers from around the world attended the Second Annual Meeting of the EVBC this year, including 15 renowned international speakers. This report presents an overview of new developments and novel research findings that emerged during the meeting.
Despite the recognized excellence of virology and bioinformatics, these two communities have interacted surprisingly sporadically, aside from some pioneering work on HIV-1 and influenza. Bringing together the Expertise of bioinformaticians and virologists is crucial, since very specific but fundamental computational approaches are required for virus research, particularly in an era of big data. Collaboration between virologists and bioinformaticians is necessary to improve existing analytical tools, cloud-based systems, computational resources, data sharing approaches, new diagnostic tools, and bioinformatic training. Here, we highlight current progress and discuss potential avenues for future developments in this promising era of virus bioinformatics. We end by presenting an overview of current technologies, and by outlining some of the Major challenges and Advantages that bioinformatics will bring to the field of virology.
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.
Near-ambient pressure XPS makes it possible to characterise samples not compatible to ultra-high vacuum, and enables the study of liquid-solid, gas-liquid and gas-solid interfaces. NAP-XPS meas-urements of biofilms, suspended nanoparticles and metal-organic frameworks were performed with EnviroESCA developed by SPECS.
An interesting application is surface characterisation of biofilms, which are bacterial communities embedded in a self-produced polysaccharide matrix. Various model systems ranging from pure polysaccharides of alginate to biofilms harvested directly from the growth medium have been char-acterised in humid conditions[1].
NAP-XPS also makes it possible to characterise nanoparticles in solution. Silver nanoparticles in aqueous solution were characterised and the Ag 3d-spectrum compared to spectra obtained of dried nanoparticles in UHV-conditions[2]. The binding energy of the Ag 3d-core level peak was shifted by 0,6 eV towards higher binding energy for suspended nanoparticles compared to the dried sample measured in UHV. This can be assigned to a change in surface potential at the water-nanoparticle interface.
Metal-organic frameworks (MOFs) are suitable materials for gas storage of small molecules due to their nanoporous, crystalline structure. However, instability in humidity remains an issue for many types of MOFs. XPS-measurements of the MOF-structure HKUST-1 were performed in various NAP-conditions to assess the stability of the sample and its interaction with the gas molecules as water, methanol and pyridine.
Synchrotron XPS in the soft-X-ray regime is suitable for the detection of light elements commonly found in biological samples. Various model systems of biofilms have been developed and characterised at synchrotron- and lab-based facilities. By obtaining the chemical composition at various information depths, the vertical distribution of iodine in an artificial biofilm have been determined.
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.
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.