Phage mediated horizontal transfer of the sopE1 gene increases enteropathogenicity of Salmonella enterica serotype Typhimurium for calves

Epidemiological evidence shows that the sopE1 gene is associated with Salmonella Typhimurium phage types causing epidemics in cattle. In this study we demonstrate that horizontal transfer of the sopE1 gene by lysogenic conversion with the SopEΦ increased enteropathogenicity of S. Typhimurium in the bovine ligated ileal loop model. These data support the hypothesis that phage mediated horizontal transfer of the sopE1 gene contributes to the emergence of epidemic cattle-associated S. Typhimurium clone

Photodynamic inactivation of different pathogenic bacteria on human skin using a novel photosensitizer hydrogel

Background The colonization of skin with pathogenic, partially antibiotic-resistant bacteria is frequently a severe problem in dermatological therapies. For instance, skin colonization with Staphylococcus aureus is even a disease-promoting factor in atopic dermatitis. The photodynamic inactivation (PDI) of bacteria could be a new antibacterial procedure. Upon irradiation with visible light, a special photosensitizer exclusively generates singlet oxygen. This reactive oxygen species kills bacteria via oxidation independent of species or strain and their antibiotic resistance profile causing no bacterial resistance on its part. Objective To investigate the antibacterial potential of a photosensitizer, formulated in a new hydrogel, on human skin ex vivo. Methods The photochemical stability of the photosensitizer and its ability to generate singlet oxygen in the hydrogel was studied. Antimicrobial efficacy of this hydrogel was tested step by step, firstly on inanimate surfaces and then on human skin ex vivo against S. aureus and Pseudomonas aeruginosa using standard colony counting. NBTC staining and TUNEL assays were performed on skin biopsies to investigate potential necrosis and apoptosis effects in skin cells possibly caused by PDI. Results None of the hydrogel components affected the photochemical stability and the life time of singlet oxygen. On inanimate surfaces as well as on the human skin, the number of viable bacteria was reduced by up to 4.8 log10 being more effective than most other antibacterial topical agents. Histology and assays showed that PDI against bacteria on the skin surface caused no harmful effects on the underlying skin cells. Conclusion Photodynamic inactivation hydrogel proved to be effective for decolonization of human skin including the potential to act against superficial skin infections. Being a water-based formulation, the hydrogel should be also suitable for the mucosa. The results of the present ex vivo study form a good basis for conducting clinical studies in vivo

Inhibitory effects of calcium or magnesium ions on PDI

Photodynamic inactivation of microorganisms (PDI) finds use in a variety of applications. Several studies report on substances enhancing or inhibiting PDI. In this study, we analyzed the inhibitory potential of ubiquitous salts like CaCl2 and MgCl2 on PDI against Staphylococcus aureus and Pseudomonas aeruginosa cells using five cationic photosensitizers methylene blue, TMPyP, SAPYR, FLASH-02a and FLASH-06a. TMPyP changed its molecular structure when exposed to MgCl2, most likely due to complexation. CaCl2 substantially affected singlet oxygen generation by MB at small concentrations. Elevated concentrations of CaCl2 and MgCl2 impaired PDI up to a total loss of bacterial reduction, whereas CaCl2 is more detrimental for PDI than MgCl2. Binding assays cannot not explain the differences of PDI efficacy. It is assumed that divalent ions tightly bind to bacterial cells hindering close binding of the photosensitizers to the membranes. Consequently, photosensitizer binding might be shifted to outer compartments like teichoic acids in Gram-positives or outer sugar moieties of the LPS in Gram-negatives, attenuating the oxidative damage of susceptible cellular structures. In conclusion, CaCl2 and MgCl2 have an inhibitory potential at different phases in PDI. These effects should be considered when using PDI in an environment that contains such salts like in tap water or different fields of food industry

Surface adhesins and exopolymers of selected foodborne pathogens

The ability of bacteria to bind different compounds and to adhere to biotic and abiotic surfaces provides them with a range of advantages, such as colonization of various tissues, internalisation, avoidance of an immune response and survival and persistence in the environment. A variety of bacterial surface structures are involved in this process and these promote bacterial adhesion in a more or less specific manner. In this review, we will focus on those surface adhesins and exopolymers in selected foodborne pathogens that are involved mainly in primary adhesion. Their role in biofilm development will also be considered when appropriate. Both the clinical impact and implications for food safety of such adhesion will be discussed.The authors are members of the EU COST Action FA1202 (CGAFA1202): A European Network for Mitigating Bacterial Colonisation and Persistence on Foods and Food Processing Environments (http://www.bacfoodnet.org/) and acknowledge this action for facilitating collaborative networking that assisted with this study. The work was further supported by the Ministry of Education, Youth and Sports of the Czech Republic (project COST LD 14015 and project LO1218 under the NPU I program), the 'Cooperation Scientifique Universitaire (CSU)' France Denmark 2012 from the Embassy of France in Denmark 'Institut Francais du Danemark' (IFD) (no. 14/2012/CSU.8.2.1), the EGIDE Programme Hubert Curien (PHC) France Germany PROCOPE 2013 2015 from the 'Ministere des Affaires Etrangeres et Europeennes' (no. 28297WG) and by the Norwegian Research Council (grant no. 192402)

Combining teaching and research: a BIP on geophysical and archaeological prospection of North Frisian medieval settlement patterns

We performed a research-oriented EU Erasmus+ Blended Intensive Program (BIP) with participants from four countries focused on North Frisian terp settlements from Roman Iron Age and medieval times. We show that the complex terp structure and environment can be efficiently prospected using combined magnetic and EMI mapping, and seismic and geoelectric profiling and drilling. We found evidence of multiple terp phases and a harbor at the Roman Iron Age terp of Tofting. In contrast, the medieval terp of Stolthusen is more simply constructed, probably uni-phase. The BIP proved to be a suitable tool for high-level hands-on education adding value to the research conducted in on-going projects

Videodaten in der Verkehrsforschung – besser auffind- und nachnutzbar dank der neuen Ontologie ListDB Onto

Handreichung zur Ontologie ListDB Onto als wichtiger Baustein für die Interoperabilität zwischen verschiedenen Videodaten in der Verkehrsforschung

Videodaten in der Verkehrsforschung – besser auffind- und nachnutzbar dank der neuen Ontologie ListDB Onto

Handreichung zur Ontologie ListDB Onto als wichtiger Baustein für die Interoperabilität zwischen verschiedenen Videodaten in der Verkehrsforschung

Videodaten in der Verkehrsforschung – besser auffind- und nachnutzbar dank der neuen Ontologie ListDB Onto

Handreichung zur Ontologie ListDB Onto als wichtiger Baustein für die Interoperabilität zwischen verschiedenen Videodaten in der Verkehrsforschung

Character, Rates, and Environmental Significance of Holocene Dust Accumulation in Archaeological Hilltop Ruins in the Southern Levant

Loess accumulated in the Negev desert during the Pleistocene and primary and secondary loess remains cover large parts of the landscape. Holocene loess deposits are however absent. This could be due low accumulation rates, lack of preservation, and higher erosion rates in comparison to the Pleistocene. This study hypothesized that archaeological ruins preserve Holocene dust. We studied soils developed on archaeological hilltop ruins in the Negev and the Petra region and compared them with local soils, paleosols, geological outcrops, and current dust. Seven statistically modeled grain size end-members were identified and demonstrate that the ruin soils in both regions consist of mixtures of local and remote sediment sources that differ from dust compositions deposited during current storms. This discrepancy is attributed to fixation processes connected with sediment-fixing agents such as vegetation, biocrusts, and/or clast pavements associated with vesicular layers. Average dust accretion rates in the ruins are estimated to be similar to 0.14 mm/a, suggesting that similar to 30% of the current dust that can be trapped with dry marble dust collectors has been stored in the ruin soils. Deposition amounts and grain sizes do not significantly correlate with wind intensity. However, precipitation may have contributed to dust accretion. A snowstorm in the Petra region delivered a significantly higher amount of sediment than rain or dry deposition. Snowfall dust had a unique particle size distribution relatively similar to the ruin soils. Wet deposition and snow might catalyze dust deposition and enhance fixation by fostering vegetation and crust formation. More frequent snowfall during the Pleistocene may have been an important mechanism of primary loess deposition in the southern Levant.Peer reviewe

Interplay of phosphate and carbonate ions with flavin photosensitizers in photodynamic inactivation of bacteria

Photodynamic inactivation (PDI) of pathogenic bacteria is a promising technology in different applications. Thereby, a photosensitizer (PS) absorbs visible light and transfers the energy to oxygen yielding reactive oxygen species (ROS). The produced ROS are then capable of killing microorganisms via oxidative damage of cellular constituents. Among other PS, some flavins are capable of producing ROS and cationic flavins are already successfully applied in PDI. When PDI is used for example on tap water, PS like flavins will encounter various ions and other small organic molecules which might hamper the efficacy of PDI. Thus, the impact of carbonate and phosphate ions on PDI using two different cationic flavins (FLASH-02a, FLASH-06a) was investigated using Staphylococcus aureus and Pseudomonas aeruginosa as model organisms. Both were inactivated in vitro at a low light exposure of 0.72 J cm-2. Upon irradiation, FLASH-02a reacts to single substances in the presence of carbonate or phosphate, whereas the photochemical reaction for FLASH-06a was more unspecific. DPBF-assays indicated that carbonate and phosphate ions decreased the generation of singlet oxygen of both flavins. Both microorganisms could be easily inactivated by at least one PS with up to 6 log10 steps of cell counts in low ion concentrations. Using the constant radiation exposure of 0.72 J cm-2, the inactivation efficacy decreased somewhat at medium ion concentrations but reached almost zero for high ion concentrations. Depending on the application of PDI, the presence of carbonate and phosphate ions is unavoidable. Only upon light irradiation such ions may attack the PS molecule and reduce the efficacy of PDI. Our results indicate concentrations for carbonate and phosphate, in which PDI can still lead to efficient reduction of bacterial cells when using flavin based PS