4.1 Biologische Materialschädigung und Referenzorganismen
Filtern
Dokumenttyp
- Zeitschriftenartikel (84) (entfernen)
Sprache
- Englisch (84) (entfernen)
Schlagworte
- Antimicrobial resistance (6)
- Bacteria (6)
- Biocides (6)
- Ectoine (5)
- Biofilm (4)
- Biofilms (4)
- Polyethylene (4)
- Wood protection (4)
- Disinfection (3)
- NAP-XPS (3)
- Osmoadaptation (3)
- Termites (3)
- Wood Protection (3)
- Antimicrobial (2)
- Bacterial adhesion (2)
- Biocorrosion (2)
- Brown-rot fungi (2)
- Condensed Matter Physics (2)
- DNA (2)
- Degradation (2)
- Energy Engineering and Power Technology (2)
- Evolution (2)
- Fuel Technology (2)
- Halomonas elongata (2)
- Horizontal gene transfer (2)
- Insect biotechnology (2)
- Isoptera (2)
- Keratin (2)
- Laser processing (2)
- Laser-induced periodic surface structures (LIPSS) (2)
- Leaching (2)
- MIC (2)
- Method development (2)
- Microbiologically influenced corrosion (2)
- NanoSIMS (2)
- Nanoparticles (2)
- Nosema ceranae (2)
- Osmia bicornis (2)
- Pseudomonas aeruginosa (2)
- Renewable Energy, Sustainability and the Environment (2)
- Tineola bisselliella (2)
- Wild bees (2)
- XPS (2)
- 2D nanomaterials (1)
- 3D printing (1)
- A-DNA conformation (1)
- Acidobacteria (1)
- Alkylating agents (1)
- Amphiphilic polymer (1)
- Anaerobic pathways (1)
- Anobium punctatum (1)
- Antagonism (1)
- Antibacterial (1)
- Antibacterial polymer (1)
- Antibacterial surfaces (1)
- Antibiotic resistance (1)
- Antibiotics (1)
- Antifouling (1)
- Antimicrobial coating (1)
- Antimicrobial test (1)
- Antimicrobials (1)
- Antiseptic agents (1)
- Artificial weathering (1)
- Aspergillus (1)
- Atomic and Molecular Physics and Optics (1)
- Automated analysis (1)
- BODIPY (1)
- Bacillus subtilis (1)
- Bacterial attachment (1)
- Bacterial cell cycle (1)
- Bacterial second messenger (1)
- Basidiomycetes (1)
- Bee diseases (1)
- Bee health (1)
- Beneficial microbes (1)
- Biocide tolerance (1)
- Biodeterioration (1)
- Biodeterioration and biodegradation (1)
- Biofilm formation (1)
- Biofilm quantification (1)
- Bioinformatics (1)
- Bioinformatics virology viruses software (1)
- Biokorrosion (1)
- Biological pest control (1)
- Biomimetic (1)
- Biosynthesis (1)
- Biphasic growth (1)
- C-di-GMP (1)
- COST action CA15114 AMICI (1)
- Calcareous deposits (1)
- Carbon steel (1)
- Carbon steel corrosion (1)
- Cathodic protection (1)
- Cell appendages (1)
- Cell studies (1)
- Cell-envelope (1)
- Cellulose synthase (1)
- Chemicals (1)
- Cleridae (1)
- Coleoptera (1)
- Compatible solute (1)
- Coniophora puteana (1)
- Conjugate (1)
- Conjugation (1)
- Coptotermes (1)
- Core microbiome (1)
- Cross-feeding (1)
- Cross-resistance (1)
- Cryo XPS (1)
- CuNPs (1)
- Cultural heritage (1)
- Cupriavidus campinensis (1)
- DSM 5009 (1)
- Decomposition point (1)
- Degradable polymer (1)
- Denitrification (1)
- Desert ecology (1)
- Dielectric heating (1)
- Dietary adaptation (1)
- Diffractive gratings (1)
- Direct laser writing (1)
- Disinfection Fuel (1)
- Disposal (1)
- Diversity (1)
- Drywood termite (1)
- Dye (1)
- E. coli (1)
- Efficacy (1)
- Electronic (1)
- Environment (1)
- Environmental conditions (1)
- Environmental simulations (1)
- Exocrine gland (1)
- External (1)
- Extremophile (1)
- F pili (1)
- Fenton-like reaction (1)
- Flow system (1)
- Fluorescence spectroscopy (1)
- Fluoride (1)
- Fluoride nanoparticles (1)
- Fluorides (1)
- Fluorolytic sol-gel synthesis (1)
- Fluorolytic sol−gel (1)
- Food fermentation (1)
- Fuel sorption (1)
- Functionalized graphene (1)
- Fungal decay (1)
- Fungicidal property (1)
- Fungiculture (1)
- Fusarium (1)
- Gene expression (1)
- Genome sequence (1)
- Geology (1)
- Graphene (1)
- Graphene–bacteria interaction (1)
- Growth-rate homeostasis (1)
- Gut symbionts (1)
- Halogenation (1)
- Halophilic bacteria (1)
- Healthcare (1)
- High density polyethylene (1)
- Holzschutzmittel (1)
- Hospital premises (1)
- Hydrogen permeation (1)
- Hydrogen storage (1)
- Hydrogenasen (1)
- Hydrophobic interaction (1)
- Hylotrupes bajulus, Anobium punctatum, natural durability, tropical wood, native wood. (1)
- Hyperarid (1)
- Hypopharynx (1)
- IR spectroscopy (1)
- Immunity (1)
- Infections (1)
- Insect evolution (1)
- Insecticide (1)
- Interdisciplinarity (1)
- Ionic liquid (1)
- Ir DNA staining approach (1)
- Issues (1)
- Korynetes caeruleus (1)
- Laboratory breeding (1)
- Labrum (1)
- Laser-induced nanostructures (1)
- Laser-modified surface (1)
- Life history data (1)
- Lifetime (1)
- Low alloy steel (1)
- Marek's virus (1)
- Mechanosensitive channel (1)
- Melting point (1)
- Melting temperature (1)
- Metabolic engineering (1)
- Metabolic flux analysis (1)
- Metabolic modeling (1)
- Metabolism (1)
- Metabolomics (1)
- Methane (1)
- Methanogen (1)
- Microbial adhesions (1)
- Microbial simulation, (1)
- Microbially Induced Corrosion (1)
- Microbiological influenced corrosion MIC (1)
- Micromonospora aurantiaca (1)
- Micropatterning (1)
- Microwaves (1)
- Model (1)
- Modeling (1)
- Modelling studies (1)
- Modified mycotoxins (1)
- Moisture (1)
- Moisture performance (1)
- Molecular clock (1)
- MscS (1)
- Mud volcanoe fluids (1)
- Multi-resistant bacteria (1)
- Multiple lines of evidence (1)
- Multiport (1)
- Mussel-inspired coating (1)
- Mussel-inspired materials (1)
- Mutation rate (1)
- Mycotoxin (1)
- Nano Particles (1)
- Natural durability (1)
- Natural products discovery (1)
- Near ambient x-ray photoelectron spectroscopy (1)
- Next generation sequencing (1)
- Nitrous oxide (1)
- Nonvolatile (1)
- One-step ionic liquids synthesis (1)
- Optical and Magnetic Materials (1)
- Osmotic shock (1)
- Osteogenesis (1)
- P. Fluorescens (1)
- Paper sizings (1)
- Particle synthesis (1)
- Pathogen spillover (1)
- Pathogen transmission (1)
- Performance (1)
- Permeability (1)
- Persian historical recipes (1)
- Persistence (1)
- Pest control (1)
- Phenotypic heterogeneity (1)
- Phenotypic variation (1)
- Photodynamic therapy (1)
- Photonics (1)
- Physical and optical characteristics (1)
- Plastic degradation (1)
- Polydopamine (1)
- Polyethylene terephthalate (1)
- Polyglycerol (1)
- Polyioinic liquid (1)
- Polymer-based products (1)
- Proteome (1)
- Pseudomonas fluorescens (1)
- Pseudomonas veronii (1)
- Ptinidae (1)
- Quasispecies (1)
- RNA-Sequencing (1)
- Radio waves (1)
- Reactive oxygen species (1)
- Reactor conditions (1)
- Resistance model (1)
- Rhizopus (1)
- Rhizopus and Aspergillus oryzae (1)
- Rhodonia placenta (1)
- Ruthenium (1)
- SEM (1)
- SEM micrography (1)
- SEM wood characterization (1)
- SIMS (1)
- Sc-ICP-ToF-MS (1)
- Self-assembled monolayer (1)
- Sensors (1)
- Silica and polystyrene nanoparticles (1)
- Silver (1)
- Single cell (1)
- Single cell microbiology (1)
- Social (1)
- Social insects (1)
- Software (1)
- Soil contact (1)
- Soldier (1)
- Solitary bees (1)
- Solute excretion (1)
- Spectral imaging (1)
- Standardisation (1)
- Suppression (1)
- Survival rates (1)
- Symbiosis (1)
- Synergy (1)
- Synthetic metabolism (1)
- Termite-associated microbes (1)
- Termitoidae (1)
- Thermodynamic (1)
- Thioimidazolium (1)
- Touch surfaces (1)
- Transcriptomics (1)
- UV-irradiation (1)
- Ultrastructure (1)
- Virology (1)
- Virulence (1)
- Viruses (1)
- Water (1)
- Water atmosphere (1)
- Water stable isotope analysis (1)
- Water uptake (1)
- White-rot fungi (1)
- Wood Modification (1)
- X-ray tomographic (1)
- Zearalenone (1)
- Zearalenone sulfate (1)
- a-zearalenol (1)
- dsDAN monolayer (1)
- iChip (1)
- pH probe (1)
- underexplored phyla (1)
Organisationseinheit der BAM
- 4 Material und Umwelt (84)
- 4.1 Biologische Materialschädigung und Referenzorganismen (84)
- 6 Materialchemie (17)
- 4.0 Abteilungsleitung und andere (8)
- 1 Analytische Chemie; Referenzmaterialien (7)
- 6.1 Oberflächen- und Dünnschichtanalyse (6)
- 6.2 Material- und Oberflächentechnologien (6)
- 5 Werkstofftechnik (3)
- 6.3 Strukturanalytik (3)
- 8 Zerstörungsfreie Prüfung (3)
- 1.2 Biophotonik (2)
- 1.7 Organische Spuren- und Lebensmittelanalytik (2)
- 1.8 Umweltanalytik (2)
- 4.3 Schadstofftransfer und Umwelttechnologien (2)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (2)
- 1.1 Anorganische Spurenanalytik (1)
- 1.4 Prozessanalytik (1)
- 3 Gefahrgutumschließungen; Energiespeicher (1)
- 3.1 Sicherheit von Gefahrgutverpackungen und Batterien (1)
- 5.1 Mikrostruktur Design und Degradation (1)
- 5.3 Polymere Verbundwerkstoffe (1)
- 5.4 Multimateriale Fertigungsprozesse (1)
- 6.6 Physik und chemische Analytik der Polymere (1)
- 6.7 Materialsynthese und Design (1)
- 7 Bauwerkssicherheit (1)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (1)
- 8.0 Abteilungsleitung und andere (1)
- 9 Komponentensicherheit (1)
- 9.0 Abteilungsleitung und andere (1)
Paper des Monats
- ja (6)
Lack of long-time stability of dsDNA-based supramolecular assemblies is an important issue that hinders their applications. In this work, 20 base pairs long dsDNA fragments [(dCdG)20
65%] composed of 65% dCdG and 35% dAdT nucleotides were tethered via a thiol to the surface of a gold electrode. The selfassembled (dCdG)20
-65% monolayer was immersed in solutions
containing ectoine, a compatible solute. Electrochemical results showed that these monolayers were stable for one month. In situ IR spectroscopy indicated that ectoine interacts weakly with the phosphate-ribose backbone, dehydrating the phosphate groups and stabilizing the A-DNA conformation. This structural reorganization led to a reorientation of nucleic acid base pairs and a local disruption of the double-helix structure. However, the conformation and orientation of the dsDNA fragment was stable in the
Ratiometric green–red fluorescent nanosensors for fluorometrically monitoring pH in the acidic range were designed from 80 nm-sized polystyrene (PS) and silica (SiO2) nanoparticles (NPs), red emissive reference dyes, and a green emissive naphthalimide pH probe, analytically and spectroscopically characterized, and compared regarding their sensing performance in aqueous dispersion and in cellular uptake studies. Preparation of these optical probes, which are excitable by 405 nm laser or LED light sources, involved the encapsulation of the pH-inert red-fuorescent dye Nile Red (NR) in the core of self-made carboxylated PSNPs by a simple swelling procedure and the fabrication of rhodamine B (RhB)-stained SiO2-NPs from a silane derivative of pH-insensitive RhB. Subsequently, the custom-made naphthalimide pH probe, that utilizes a protonation-controlled photoinduced electron transfer process, was covalently attached to the carboxylic acid groups at the surface of both types of NPs. Fluorescence microscopy studies with the molecular and nanoscale optical probes and A549 lung cancer cells confirmed the cellular uptake of all probes and their penetration into acidic cell compartments, i.e., the lysosomes, indicated by the switching ON of the green naphthalimide fluorescence. This underlines their suitability for intracellular pH sensing, with the SiO2-based nanosensor revealing the best performance regarding uptake speed and stability.
For osmoadaptation the halophilic bacterium Halomonas elongata synthesizes as its main compatible solute the aspartate derivative ectoine. H. elongata does not rely entirely on synthesis but can accumulate ectoine by uptake from the surrounding environment with the help of the osmoregulated transporter TeaABC. Disruption of the TeaABC-mediated ectoine uptake creates a strain that is constantly losing ectoine to the medium. However, the efflux mechanism of ectoine in H. elongata is not yet understood. H. elongata possesses four genes encoding mechanosensitive channels all of which belong to the small conductance type (MscS). Analysis by qRT-PCR revealed a reduction in transcription of the mscS genes with increasing salinity. The response of H. elongata to hypo- and hyperosmotic shock never resulted in up-regulation but rather in downregulation of mscS transcription. Deletion of all four mscS genes created a mutant that was unable to cope with hypoosmotic shock. However, the knockout mutant grew significantly faster than the wildtype at high salinity of 2 M NaCl, and most importantly, still exported 80% of the ectoine compared to the wildtype. We thus conclude that a yet unknown system, which is independent of mechanosensitive channels, is the major export route for ectoine in H. elongata.
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.
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.
In this study, we investigated the diverse range of materials used for sizing in Iranian paper manuscripts during the Timurid (fifteenth century) to Safavid (sixteenth century) and Qajar (nineteenth century) periods. Our approach combined historical analysis with scientific examination of reconstructed sizings. We reconstructed 15 sizing materials based on identified Persian historical recipes and analysed their physical, optical, and spectral characteristics. Additionally, we assessed their behaviour against the mould fungus Aspergillus flavus. The results revealed distinctive properties for each sizing material, shedding light on their potential applications in paper preservation. Furthermore, our investigation demonstrated variations in hygroscopicity, thickness, grammage, and ash content post-sizing. The sizing materials also exhibited different effects on paper reflectance properties. Additionally, our study revealed insights into the impact of sizing on burnished papers, indicating that the mechanical process of burnishing did not significantly alter the chemical composition or spectral properties of the paper, with only minor changes in brightness observed in specific cases. All tested sizing materials supported varying levels of mould growth, indicating potential implications for paper conservation. Our findings provide valuable insights into the historical practices of Iranian paper sizing and offer practical considerations for the preservation of paper manuscripts.
Maintaining and modulating mechanical anisotropy is essential for biological processes. However, how this is achieved at the microscopic scale in living soft matter is not always clear. Although Brillouin light scattering (BLS) spectroscopy can probe the mechanical properties of materials, spatiotemporal mapping of mechanical anisotropies in living matter with BLS microscopy has been complicated by the need for sequential measurements with tilted excitation and detection angles. Here we introduce Brillouin light scattering anisotropy microscopy (BLAM) for mapping high-frequency viscoelastic anisotropy inside living cells. BLAM employs a radial virtually imaged phased array that enables the collection of angle-resolved dispersion in a single shot, thus enabling us to probe phonon modes in living matter along different directions simultaneously. We demonstrate a precision of 10 MHz in the determination of the Brillouin frequency shift, at a spatial resolution of 2 µm. Following proof-of-principle experiments on muscle myofibres, we apply BLAM to the study of two fundamental biological processes. In plant cell walls, we observe a switch from anisotropic to isotropic wall properties that may lead to asymmetric growth. In mammalian cell nuclei, we uncover a spatiotemporally oscillating elastic anisotropy correlated to chromatin condensation. Our results highlight the role that high-frequency mechanics can play in the regulation of diverse fundamental processes in biological systems. We expect BLAM to find diverse applications in biomedical imaging and material characterization.
The growth rate of single bacterial cells is continuously disturbed by random fluctuations in biosynthesis rates and by deterministic cell-cycle events, such as division, genome duplication, and septum formation.
It is not understood whether, and how, bacteria reject these growth-rate disturbances. Here, we quantified growth and constitutive protein expression dynamics of single Bacillus subtilis cells as a function of cell-cycle progression. We found that, even though growth at the population level is exponential, close inspection of the cell cycle of thousands of single Bacillus subtilis cells reveals systematic deviations from exponential growth.
Newborn cells display varying growth rates that depend on their size. When they divide, growth-rate Variation has decreased, and growth rates have become birth size independent. Thus, cells indeed compensate for growth-rate disturbances and achieve growth-rate homeostasis. Protein synthesis and growth of single cells displayed correlated, biphasic dynamics from cell birth to division. During a first phase of variable duration, the absolute rates were approximately constant and cells behaved as sizers. In the second phase, rates increased, and growth behavior exhibited characteristics of a timer strategy. These findings demonstrate that, just like size homeostasis, growth-rate homeostasis is an inherent property of single cells that is achieved by cell-cycle-dependent rate adjustments of biosynthesis and growth.
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.
Numerous non-native tree species are given attention with respect to the reforestation of calamity areas in Europe. Among them, several species may form durable wood which can be used for outdoor applications, but differences in wood durability are expected between original and European growth sites. This study aimed at examining the biological durability against wooddestroying fungi and water permeability of German-grown Dawn redwood (Metasequoia glyptostroboides) and Port Orford cedar (Chamaecyparis lawsoniana). The heartwood of both wood species was assigned to durability class 4 (DC 4, less durable) in soil contact and DC 1–4 (very to less durable) against wood-destroying basidiomycetes. However, according to the Meyer-Veltrup model, their material resistance dose was notably higher compared to the reference species Norway spruce (Picea abies), and the resulting service life of above ground structures should be a multiple of the reference.
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.
Antimicrobial resistance (AMR) is a global health problem with the environment being an important compartment for the evolution and transmission of AMR. Previous studies showed that de-novo mutagenesis and horizontal gene transfer (HGT) by conjugation or transformation – important processes underlying resistance evolution and spread - are affected by antibiotics, metals and pesticides. However, natural microbial communities are also frequently exposed to biocides used as material preservatives, but it is unknown if these substances induce mutagenesis and HGT. Here, we show that active substances used in material preservatives can increase rates of mutation and conjugation in a species- and substance-dependent manner, while rates of transformation are not increased. The bisbiguanide chlorhexidine digluconate, the quaternary ammonium compound didecyldimethylammonium chloride, the metal copper, the pyrethroid-insecticide permethrin, and the azole-fungicide propiconazole increase mutation rates in Escherichia coli, whereas no increases were identified for Bacillus subtilis and Acinetobacter baylyi.
Benzalkonium chloride, chlorhexidine and permethrin increased conjugation in E. coli. Moreover, our results show a connection between the RpoS-mediated general stress and the RecA-linked SOS response with increased rates of mutation and conjugation, but not for all biocides. Taken together, our data show the importance of assessing the contribution of material preservatives on AMR evolution and spread.
The development of the microbiologically influenced corrosion ( MIC ) -specific inductively coupled plasma-time of flight-mass spectrometry ( ICP-ToF-MS ) analytical method presented here, in combination with the investigation of steel-MIC interactions, contributes significantly to progress in instrumental MIC analysis. For this, a MIC-specific staining procedure was developed, which ensures the analysis of intact cells. It allows the analysis of archaea at a single cell level, which is extremely scarce compared to other well-characterized organisms. The detection method revealed elemental selectivity for the corrosive methanogenic strain Methanobacterium -affiliated IM1. Hence, the possible uptake of individual elements from different steel samples was investigated and results showed the cells responded at a single-cell level to the different types of supplemented elements and displayed the abilities to uptake chromium, vanadium, titanium, cobalt, and molybdenum from solid metal surfaces. The methods developed and information obtained will be used in the future to elucidate underlying mechanisms, compliment well-developed methods, such as SEM-EDS, and develop novel material protection concepts.
In this study, femtosecond laser-induced sub-micrometer structures are generated to modify polyethylene (PE) surface topographies. These surfaces were subjected to bacterial colonization studies with Escherichia coli and Staphylococcus aureus as test strains. The results reveal that the nanostructures do not influence S. aureus coverage, while the adhesion of E. coli is reduced.
New antibacterial agents are urgently required to fight the emergence of antibiotic-resistant bacteria. We recently synthesized the first thioimidazolium ionene, which has antibacterial properties and can degrade in various media. This dual functionality is crucial in order to limit the environmental impact of these biocides. We have found that our polymer is stronger than benzalkonium chloride (BAC) against Pseudomonas aeruginosa and also readily degrades in the presence of base, while remaining stable in acidic environments. These results highlight a new emerging class of antibacterial degradable polymers.
Salt tolerance in the γ-proteobacterium Halomonas elongata is linked to its ability to produce the compatible solute ectoine. The metabolism of ectoine production is of great interest since it can shed light on the biochemical basis of halotolerance as well as pave the way for the improvement of the biotechnological production of such compatible solute. Ectoine belongs to the biosynthetic family of aspartate-derived amino-acids. Aspartate is formed from oxaloacetate, thereby connecting ectoine production to the anaplerotic reactions that refill carbon into the tricarboxylic acid cycle (TCA cycle). This places a high demand on these reactions and creates the need to regulate them not only in response to growth but also in response to extracellular salt concentration. In this work, we combine modeling and experiments to analyze how these different needs shape the anaplerotic reactions in H. elongata. First, the stoichiometric and thermodynamic factors that condition the flux distributions are analyzed, then the optimal patterns of operation for oxaloacetate production are calculated. Finally, the phenotype of two deletion mutants lacking potentially relevant anaplerotic enzymes: phosphoenolpyruvate carboxylase (Ppc) and oxaloacetate decarboxylase (Oad) are experimentally characterized. The results show that the anaplerotic reactions in H. elongata are indeed subject to evolutionary pressures that differ from those faced by other gram-negative bacteria. Ectoine producing halophiles must meet a higher metabolic demand for oxaloacetate and the reliance of many marine bacteria on the Entner-Doudoroff pathway compromises the anaplerotic efficiency of Ppc, which is usually one of the main enzymes fulfilling this role. The anaplerotic flux in H. elongata is contributed not only by Ppc but also by Oad, an enzyme that has not yet been shown to play this role in vivo. Ppc is necessary for H. elongata to grow normally at low salt concentrations but it is not required to achieve near maximal growth rates as long as there is a steep sodium gradient. On the other hand, the lack of Oad presents serious difficulties to grow at high salt concentrations. This points to a shared role of these two enzymes in guaranteeing the supply of oxaloacetate for biosynthetic reactions.
Biofilms cause complications and high costs in both industry and medicine. Of particular interest are bacterial infections of prosthetic materials, which usually cannot be eliminated due to the high antibiotic resistance known for bacteria forming biofilms. The search for new materials and coatings with lower colonization potential and antibacterial activity is of great importance to reduce biofilm formation. However, there is no standardized procedure to examine the colonization characteristics of bacteria in the Biofilm state in situ. Here, we describe an automated epifluorescence microscopy system for the semi-quantitative analysis of three-dimensional (3D) biofilms on various surfaces. To analyze adherent bacteria, three materials (glass, steel and titanium) were incubated with bacteria in a flow chamber system. After fluorescence staining of the bacteria, automated image capturing, quantification of the bacteria, measurement of the colonized area and determination of the 3D biofilm height were carried out by using novel software.
Furthermore, the materials were examined for their surface topography using white light scanning interferometry. Titanium compared to glass showed a significantly higher number of adherent bacteria.
We argue that this was due to the higher microroughness of titanium. The colonized area was in accordance with the number of adherent bacteria and was also significantly larger on titanium coupons compared to glass. Maximum 3D biofilm height on glass coupons was significantly lower compared to the ones on steel and titanium. This novel method enables the standardized, automated investigation of the colonization with bacteria on different materials. This approach can considerably support the characterization of new material surfaces and their innovative coatings by analyzing the amount of attached Bacteria and thickness of biofilms in situ and eliminates the need of conventional cultivation.
Pseudomonas aeruginosa MPAO1 is the parental strain of the widely utilized transposon mutant collection for this important clinical pathogen. Here, we validate a model system to identify genes involved in biofilm growth and biofilm-associated antibiotic resistance. Our model employs a genomics-driven workflow to assemble the complete MPAO1 genome, identify unique and conserved genes by comparative genomics with the PAO1 reference strain and genes missed within existing assemblies by proteogenomics. Among over 200 unique MPAO1 genes, we identified six general essential genes that were overlooked when mapping public Tn-seq data sets against PAO1, including an antitoxin. Genomic data were integrated with phenotypic data from an experimental workflow using a user-friendly, soft lithography-based microfluidic flow chamber for biofilm growth and a screen with the Tn-mutant library in microtiter plates. The screen identified hitherto unknown genes involved in biofilm growth and antibiotic resistance. Experiments conducted with the flow chamber across three laboratories delivered reproducible data on P. aeruginosa biofilms and validated the function of both known genes and genes identified in the Tn-mutant screens. Differential Protein abundance data from planktonic cells versus biofilm confirmed the upregulation of candidates known to affect biofilm formation, of structural and secreted proteins of type VI secretion systems, and provided proteogenomic evidence for some missed MPAO1 genes. This integrated, broadly applicable model promises to improve the mechanistic understanding of biofilm formation, antimicrobial tolerance, and resistance evolution in biofilms.
The halophilic γ-proteobacterium Halomonas elongata DSM 2581T thrives at salt concentrations well above 10 % NaCl (1.7 M NaCl). A well-known osmoregulatory mechanism is the accumulation of the compatible solute ectoine within the cell in response to osmotic stress. While ectoine accumulation is central to osmoregulation and promotes resistance to high salinity in halophilic bacteria, ectoine has this effect only to a much lesser extent in non-halophiles. We carried out transcriptome analysis of H. elongata grown on two different carbon sources (acetate or glucose), and low (0.17 M NaCl), medium (1 M), and high salinity (2 M) to identify additional mechanisms for adaptation to high saline environments. To avoid a methodological bias, the transcripts were evaluated by applying two methods, DESeq2 and Transcripts Per Million (TPM). The differentially transcribed genes in response to the available carbon sources and salt stress were then compared to the transcriptome profile of Chromohalobacter salexigens, a closely related moderate halophilic bacterium. Transcriptome profiling supports the notion that glucose is degraded via the cytoplasmic Entner-Doudoroff pathway, whereas the Embden-Meyerhoff-Parnas pathway is employed for gluconeogenesis. The machinery of oxidative phosphorylation in H. elongata and C. salexigens differs greatly from that of non-halophilic organisms, and electron flow can occur from quinone to oxygen along four alternative routes. Two of these pathways via cytochrome bo' and cytochrome bd quinol oxidases seem to be upregulated in salt stressed cells. Among the most highly regulated genes in H. elongata and C. salexigens are those encoding chemotaxis and motility proteins, with genes for chemotaxis and flagellar assembly severely downregulated at low salt concentrations. We also compared transcripts at low and high-salt stress (low growth rate) with transcripts at optimal salt concentration and found that the majority of regulated genes were down-regulated in stressed cells, including many genes involved in carbohydrate metabolism, while ribosome synthesis was up-regulated, which is in contrast to what is known from non-halophiles at slow growth. Finally, comparing the acidity of the cytoplasmic proteomes of non-halophiles, extreme halophiles and moderate halophiles suggests adaptation to an increased cytoplasmic ion concentration of H. elongata. Taken together, these results lead us to propose a model for salt tolerance in H. elongata where ion accumulation plays a greater role in salt tolerance than previously assumed.
RNA virus populations are composed of highly diverse individuals that form a cloud of related sequences commonly referred to as a ‘quasispecies’1–3. This diversity arises as a consequence of low-fidelity genome replication4,5. By contrast, DNA Virus populations contain more uniform individuals with similar fitness6.
Genome diversity is often correlated with increased Fitness in RNA viruses, while DNA viruses are thought to require more faithful genome replication. During DNA replication, erroneously incorporated bases are removed by a 3′-5′ exonuclease, a highly conserved enzymatic function of replicative DNA but not RNA polymerases. This proofreading process enhances replication fidelity and ensures the genome integrity of DNA organisms, including large DNA viruses7. Here, we show that a herpesvirus can tolerate impaired exonucleolytic proofreading, resulting in DNA virus populations, which, as in RNA viruses8, are composed of highly diverse genotypes of variable individual fitness. This indicates that herpesvirus mutant diversity may compensate for individual Fitness loss. Notably, in vivo infection with diverse virus populations results in a marked increase in virulence compared to genetically homogenous parental virus. While we cannot exclude that the increase in virulence is caused by selection of and/or interactions between individual genotypes, our findings are consistent with quasispecies dynamics. Our results contrast with traditional views of DNA virus replication and evolution, and indicate that a substantial increase in population diversity can lead to higher virulence.