The feasibility of improved live-dead distinction in qPCR-based microbial source tracking.

PCR-based microbial source tracking (MST) has become a useful tool to identify dominant sources of fecal pollution in water. The method has previously been successfully combined with viability PCR (using propidium monoazide) allowing the preferential detection of membrane-intact bacteria. This study aimed at further improving the selectivity for intact cells when targeting host-specific markers in Bacteroidales bacteria.

The River Ruhr - an urban river under particular interest for recreational use and as a raw water source for drinking water: The collaborative research project "Safe Ruhr" - microbiological aspects.

Along the intense industrialization of the Ruhr valley (Germany), the River Ruhr became increasingly polluted. Over time, using it for recreational purposes became a serious health hazard and bathing was banned due to chemical and microbiological risks. The purpose of the collaborative project "Safe Ruhr" was to verify the current status and to provide a scientific basis for lifting the bathing ban.

Developing an easy-to-apply model for identifying relevant pathogen pathways into surface waters used for recreational purposes.

Swimming in inner-city surface waters is popular in the warm season, but can have negative consequences such as gastro-intestinal, ear and skin infections. The pathogens causing these infections commonly enter surface waters via several point source discharges such as the effluents from wastewater treatment plants and sewer overflows, as well as through diffuse non-point sources such as surface runoff. Nonetheless, the recreational use of surface waters is attractive for residents.

Reducing pathogens in combined sewer overflows using ozonation or UV irradiation.

Fecal contamination of water resources is a major public health concern in densely populated areas since these water bodies are used for drinking water production or recreational purposes. A main source of this contamination originates from combined sewer overflows (CSOs) in regions with combined sewer systems. Thus, the treatment of CSO discharges is urgent.

Occurrence and fate of the angiotensin II receptor antagonist transformation product valsartan acid in the water cycle--a comparative study with selected β-blockers and the persistent anthropogenic wastewater indicators carbamazepine and acesulfame.

The substantial transformation of the angiotensin II receptor antagonist valsartan to the transformation product 2'-(2H-tetrazol-5-yl)-[1,1'-biphenyl]-4-carboxylic acid (referred to as valsartan acid) during the activated sludge process was demonstrated in the literature and confirmed in the here presented study. However, there was a severe lack of knowledge regarding the occurrence and fate of this compound in surface water and its behavior during drinking water treatment. In this work a comparative study on the occurrence and persistency of valsartan acid, three frequently used β-blockers (metoprolol, atenolol, and sotalol), atenolol acid (one significant transformation product of atenolol and metoprolol), and the two widely distributed persistent anthropogenic wastewater indicators carbamazepine and acesulfame in raw sewage, treated wastewater, surface water, groundwater, and tap water is presented.

Simultaneous monitoring of biofilm growth, microbial activity, and inorganic deposits on surfaces with an in situ, online, real-time, non-destructive, optical sensor.

Deposits on surfaces in water-bearing systems, also known as 'fouling', can lead to substantial losses in the performance of industrial processes as well as a decreased product quality. Early detection and localization of such deposits can, to a considerable extent, save such losses. However, most of the surfaces that become fouled, for example, in process water pipes, membrane systems, power plants, and food and beverage industries, are difficult to access and analyses conducted on the water phase do not reveal the site or extent of deposits.

Grafted glycopolymer-based receptor mimics on polymer support for selective adhesion of bacteria.

A sugar-containing monomer (2-lactobionamidoethyl methacrylate, LAMA) was grafted on a polypropylene (PP) microfiltration membrane surface by UV-induced graft copolymerization. The degree of grafting can be controlled by variation of monomer concentration, UV irradiation time, and photoinitiator concentration. Fourier transform infrared spectroscopy and scanning electron microscopy were employed to confirm the surface modification on the membranes.

Influence of biofilms on the movement of colloids in porous media. Implications for colloid facilitated transport in subsurface environments.

Colloid transport through porous media can be influenced by the presence of biofilms. Sterile and non-sterile sand columns were investigated using Laponite RD as model colloid and a highly mucoid strain of Pseudomonas aeruginosa as model biofilm former. Laponite RD was marked specifically by fluorescent complexes with rhodamine 6G.

Optically transparent porous medium for nondestructive studies of microbial biofilm architecture and transport dynamics.

We describe a novel and noninvasive, microscopy-based method for visualizing the structure and dynamics of microbial biofilms, individual fluorescent microbial cells, and inorganic colloids within a model porous medium. Biofilms growing in flow cells packed with granules of an amorphous fluoropolymer could be visualized as a consequence of refractive index matching between the solid fluoropolymer grains and the aqueous immersion medium. In conjunction with the capabilities of confocal microscopy for nondestructive optical sectioning, the use of amorphous fluoropolymers as a solid matrix permits observation of organisms and dynamic processes to a depth of 2 to 3 mm, whereas sediment biofilms growing in sand-filled flow cells can only be visualized in the region adjacent to the flow cell wall.

Alginate acetylation influences initial surface colonization by mucoid Pseudomonas aeruginosa.

Mucoid strains of Pseudomonas aeruginosa overproduce the exopolysaccharide alginate, which is substituted with O-acetyl groups. Under non-growing conditions in phosphate buffer, a mucoid clinical strain formed microcolonies on steel surfaces, while an acetylation-defective mutant was unable to form cell clusters. Enzymatic degradation of alginate by alginate lyase prevented microcolony formation of the mucoid parent strain.

Pseudomonas aeruginosa lectin LecB is located in the outer membrane and is involved in biofilm formation.

Pseudomonas aeruginosa is an opportunistic pathogen which causes a variety of diseases, including respiratory tract infections in patients suffering from cystic fibrosis. Therapeutic treatment of P. aeruginosa infections is still very difficult because the bacteria exhibit high intrinsic resistance against a variety of different antibiotics and, in addition, form stable biofilms, e.

Use of an oxonol dye in combination with confocal laser scanning microscopy to monitor damage to Staphylococcus aureus cells during colonisation of silver-coated vascular grafts.

The antimicrobial silver-coating of medical prostheses is regarded as a means to reduce the risk of bacterial colonisation after implantation. The effect of a silver-coating of vascular grafts on biofilm formation was assessed in batch cultures of Staphylococcus aureus, using confocal laser scanning microscopy. Total cells in biofilms were analysed by staining with the DNA-binding fluorochrome SYTO 62 and the proportion of damaged cells was quantified with the membrane potential-sensitive dye bis-(1,3-dibutylbarbituric acid) trimethine oxonol.

Interactions between laponite and microbial biofilms in porous media: implications for colloid transport and biofilm stability.

Quartz sand columns and sand-filled microscope flow cells were used to investigate the transport characteristics of the clay colloid laponite, and a biofilm-forming bacterium, Pseudomonas aeruginosa SG81. Separate experiments were performed with each particle to determine their individual transport characteristics in clean sand columns. In a second set of experiments, bacterial biofilms were formed prior to introduction of the clay colloids.

Application of fluorescently labelled lectins for the visualization and biochemical characterization of polysaccharides in biofilms of Pseudomonas aeruginosa.

Fluorescently labelled lectins were used in combination with epifluorescence microscopy and confocal laser scanning microscopy to allow the visualization and characterization of carbohydrate-containing extracellular polymeric substances (EPS) in biofilms of Pseudomonas aeruginosa. A mucoid strain characterized by an overproduction of the exopolysaccharide alginate, and an isogenic, non-mucoid strain were used. Model biofilms grown on polycarbonate filters were treated with lectins concanavalin A (ConA) and wheat germ agglutinin (WGA) that were fluorescently labelled with fluorescein isothiocyanate or tetramethyl rhodamine isothiocyanate.