Drug targeting to the colon via the oral administration route for local treatment of e.g. inflammatory bowel disease and colonic cancer has several advantages such as needle-free administration and ...low infection risk. A new source for delivery is plant-polysaccharide based delivery platforms such as Rhamnogalacturonan-I (RG-I). In the gastro-intestinal tract the RG-I is only degraded by the action of the colonic microflora. For assessment of potential drug delivery properties, RG-I based microcapsules (~1 μm in diameter) were prepared by an interfacial poly-addition reaction. The cross-linked capsules were loaded with a fluorescent dye (model drug). The capsules showed negligible and very little in vitro release when subjected to media simulating gastric and intestinal fluids, respectively. However, upon exposure to a cocktail of commercial RG-I cleaving enzymes, ~ 9 times higher release was observed, demonstrating that the capsules can be opened by enzymatic degradation. The combined results suggest a potential platform for targeted drug delivery in the terminal gastro-intestinal tract.
Extracellular polymeric substances (EPSs) are involved in both detrimental and beneficial consequences of microbial aggregates such as biofilms, flocs and biological sludges. In biofouling, they are ...responsible for the increase of friction resistance, change of surface properties such as hydrophobicity, roughness, colour, etc. In biocorrosion of metals they are involved by their ability to bind metal ions. In bioweathering, they contribute by their complexing properties to the dissolution of minerals. The EPSs represent a sorption site for pollutants such as heavy metal ions and organic molecules. This can lead to a burden in wastewater sludge; on the other hand, the sorption properties can be used for water purification. Other biotechnological uses of EPS exploit their contribution to viscosity, e.g., in food, paints and oil-drilling 'muds'; their hydrating properties are also used in cosmetics and pharmaceuticals. Furthermore, EPSs may have potential uses as biosurfactants, e.g., in tertiary oil production, and as biological glue. EPSs are an interesting component of all biofilm systems and still hold a large biotechnological potential.
Drinking water distribution system biofilms were investigated for the presence of hygienically relevant microorganisms. Early biofilm formation was evaluated in biofilm reactors on stainless steel, ...copper, polyvinyl chloride (PVC) and polyethylene coupons exposed to unchlorinated drinking water. After 12 to 18 months, a plateau phase of biofilm development was reached. Surface colonization on the materials ranged between 4 x 10(6) and 3 x 10(7) cells/cm2, with heterotrophic plate count (HPC) bacteria between 9 x 10(3) and 7 x 10(5) colony-forming units (cfu)/cm2. Established biofilms were investigated in 18 pipe sections (2 to 99 years old) cut out from distribution pipelines. Materials included cast iron, galvanized steel, cement and PVC. Colonization ranged from 4 x 10(5) to 2 x 10(8) cells/cm2, HPC levels varied between 1 and 2 x 10(5) cfu/cm2. No correlation was found between extent of colonization and age of the pipes. Using cultural detection methods, coliform bacteria were rarely found, while Escherichia coli, Pseudomonas aeruginosa and Legionella spp. were not detected in the biofilms. In regular operation, distribution system biofilms do not seem to be common habitats for pathogens. However, nutrient-leaching materials like rubber-coated valves were observed with massive biofilms which harboured coliform bacteria contaminating drinking water.
The design of a general-purpose PreAmplifier-DIscriminator ASIC chip, PADI, is presented in this article. PADI is intended to be used as Front-End-Electronics (FEE) for reading out the timing ...Resistive-Plate Chambers (RPCs) in the time-of-flight (ToF) wall of the CBM detector for the future FAIR facility in Darmstadt-Germany, which will comprise about 100,000 channels in a 150 m 2 area. The evolution of this 0.18 μm CMOS technology design will be presented, from the first prototype PADI-1 to the last one, PADI-8, as well as its features and test results.
In this publication we present a detailed study of viscoelastic biofilms of Pseudomonas aeruginosa. Sample solutions were extracted from biofilm layers grown on Pseudomonas isolation agar. This ...aqueous solutions of extracellular polymeric substances exhibit weak elastic effects caused by entanglements and a small number of permanent junction points formed by calcium ions. The cross-linking mechanisms are confirmed by the Cox-Merz rule and dynamic frequency sweep tests, which result in an average lifetime of junction points of the order of 17 ms. The experimental data reveal 3.4×10^sup 17^ elastically effective chains per liter of solution and no significant temperature effects in the regime between 2 and 24 °C. This result coincides pretty well with the concentration of dissolved polymer chains (2.9×10^sup 17^ molecules/l). Upon addition of calcium ions, one observes the formation of stable supermolecular networks with permanent junction points. These cross-linking points did not show thermal fluctuations in time zones between 10 ms and several hours. The entanglement density of these gels is of the same order as observed in the non-cross-linked sol state (entrapped entanglements). In spite of the different molecular composition alginate gels show the same type of cross-linking mechanism as gels of extracellular polymeric substances.PUBLICATION ABSTRACT
In this work we present a systematic, theoretical investigation of the 13C NMR chemical shifts for several mono-, di- and trisaccharides in the solid state. The chemical shifts have been calculated ...using density functional theory (DFT) together with the gauge including the projector augmented wave (GIPAW) method as implemented in the CASTEP program. We studied the changes in the 13C NMR chemical shifts in particular due to the formation of one or two glycosidic linkages and due to crystal water. The largest changes, up to 14 ppm, are observed between the mono- and disaccharides and typically for the glycosidic linkage atoms, but not in all cases. An analysis of the bond angles at the glycosidic linkage and the observed changes in chemical shifts displays no direct correlation between them. Somewhat smaller changes in the range of 2 to 5 ppm are observed when single crystal water molecules are close to some of the atoms. Relating the changes in the chemical shifts of the carbon atoms closest to the crystal water to the distance between them does, however, not lead to a simple relation between them.
Biofouling is a biofilm problem and any anti-fouling strategy will be greatly improved if the site and extent of biofilm growth can be monitored. A suitable monitoring system will provide early ...warning capacity and allow for specific optimization of countermeasures. As water samples do not give reliable information about biofilms, surface sampling is mandatory. Conventional biofilm monitoring techniques rely on removal of material from representative sites or on analysis of test surfaces which have been exposed. This procedure is time consuming and, depending on the parameters to be measured, requires skilled laboratory personnel. There is a strong demand for direct, on-line, in situ, continuous, non-destructive real-time information about biofilms in a system. Such demands can only be fulfilled by physical or physico-chemical methods, a number of which have already been successfully applied for biofilm monitoring. It is important, however, to be aware of the actual parameter they refer to in order to interpret the data properly. Three levels of information can be identified: (i) systems which detect increase and decrease of material accumulating on a surface but cannot differentiate between biomass and other components of a deposit, (ii) systems which provide biological information and distinguish between biotic and abiotic material, and (iii) systems which provide detailed chemical information. Examples for all three levels are presented and discussed.
Based on the latest knowledge about microorganisms resistant towards extreme conditions on Earth and results of new complex models on the development of the Martian atmosphere we quantitatively ...examined the water-bearing properties of selected extremophiles and simulated Martian regolith components and their interaction with water vapor under close to Martian environmental conditions. Three different species of microorganisms have been chosen and prepared for our study: Deinococcus geothermalis, Leptothrix sp. OT_B_406, and Xanthoria elegans. Further, two mineral mixtures representing the early and the late Martian surface as well as montmorillonite as a single component of phyllosilicatic minerals, typical for the Noachian period on Mars, were selected. The thermal mass loss of the minerals and bacteria-samples was measured by thermoanalysis. The hydration and dehydration properties were determined under close to Martian environmental conditions by sorption isotherm measurements using a McBain-Bakr quartz spring balance. It was possible to determine the total water content of the materials as well as the reversibly bound water fraction as function of the atmospheres humidity by means of these methods. Our results are important for the evaluation of future space mission outcomes including astrobiological aspects and can support the modeling of the atmosphere/surface interaction by showing the influence on the water inventory of the upper most layer of the Martian surface.
•Water-bearing behavior of selected bacteria and simulated Martian soil studied.•Reversibly bonded water of microorganisms as function of humidity determined.•Data may support modeling humidity/surface interaction of the Martian atmosphere.•Results can improve deepened evaluation of orbital or rover Mars missions.
•Real-time monitoring of fermentation parameters is important for modern industries.•Analysis of phosphates and ammonium in a wide range of concentration (10−100 mM).•Use of synthetic samples ...provided a dataset with completely uncorrelated analytes.•Mid and Near infrared spectroscopy were evaluated in fermentation-like media.•Chemometric models on Mid-infrared spectra had prediction errors lower than 5 %.
Real-time monitoring of bioprocesses plays a key-role in modern industries, providing new information on full-scale production, thus enabling control of the process and allowing it to run at optimal conditions while minimizing waste. Monitoring of phosphates and ammonium in fermentation processes has a twofold interest: they are important nutrients for living organisms while at the same time constituting environmental nutrient pollutants, for which unnecessary use and disposal must be avoided. In this report, the possibility of simultaneous analysis of phosphates and ammonium in fermentations was verified using spectroscopy-based methods combined with chemometrics to construct calibration models. To achieve this, the models were based on synthetic samples mimicking real fermentation media, providing a dataset where the analytes were completely uncorrelated. Different at-line techniques (mid- and near- infrared spectroscopy, MIR and NIR) were evaluated for their ability to monitor quickly both analytes, in a wide range of concentrations (10−100 mM), in three media of different complexities. Partial Least Squares (PLS) models on MIR spectroscopy gave very good results, with prediction errors lower than 5 % for both analytes in all datasets. In contrast, the results for PLS models on NIR spectroscopy were inferior (prediction errors between 3 and 26 %) for both analytes, as, in the case of phosphate, it could be demonstrated that the model was based on based on indirect predictions.
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