Occurrence of Legionella in groundwater: an ecological study

Abstract The natural habitat of Legionella is the water environment. Little is known about their presence in groundwaters in spite of the fact that many millions around the globe regularly rely on groundwaters. This pilot study was aimed at evaluating the occurrence of Legionella in groundwater samples (water and biofilms) collected from various sites. Water and biofilm samples from selected groundwater sources were examined for Legionella using culture media (selective and non-selective) and a semi-nested PCR assay. Innovative approaches such as immunomagnetic separation (IMS) in combination with cultivation and flow cytometry were also evaluated. The findings available thus far show that (a) Legionella could be readily recovered from groundwater samples by cultivation even though their numbers showed considerable variations, (b) surprisingly, the PCR methodology was not yet as sensitive as cultivation and (c) flow cytometry was not directly applicable on natural samples because of debris and the high number of heterotrophic associated microflora from which some members were likely to cross-react with the monoclonal antibody used for separation procedures (IMS)

Effect of nano-Al2O3 addition on the microstructure and erosion wear of HVOF sprayed NiCrSiB coatings

Development of nanostructured high velocity oxy-fuel (HVOF) coatings with low porosity, high strength and increased wear resistance is still in its infancy. Combining nanoparticles with conventional microscale powders are increasingly being investigated to use with feedstock materials for thermal spray processes. Accordingly, this work investigates the addition of nano-Al2O3 particles on the microstructure and erosion wear of NiCrSiB HVOF coating in a stainless steel (AISI 304) substrate. Particle analysis of the NiCrSiB feedstock was conducted and the maximum allowable addition of Al2O3 nanoparticles have been identified using the 'mass mixture ratio' model considering both the particle size and density. Consequently, two cases are considered and their performance analysed: a maximum allowable case of 1.4 wt%, followed by a 0.17 wt% addition of nano-Al2O3 with NiCrSiB. Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and x-ray Diffraction (XRD) analysis were employed to inform the microstructure, material composition and phase spectrum of the resulting coatings. Subsequently, the nanostructured coating was exposed to both a pull-off adhesion strength test and hot air jet (450 °C) hard particle erosion to characterise its performance. It was found that the microhardness of the HVOF NiCrSiB coating improved from 576 HV0.3 to 748 HV0.3 with the addition of 1.4 wt% nano-Al2O3. Furthermore, the nanostructured coating also exhibited high erosion resistance at a 90° erodent impact angle. The increase in erosion wear resistance was due to the increase in the hardness as a result of the nano-Al2O3 addition.Published onlin

Systems analyses reveal the resilience of Escherichia coli physiology during accumulation and export of the nonnative organic acid citramalate

© 2019 Webb et al. Productivity of bacterial cell factories is frequently compromised by stresses imposed by recombinant protein synthesis and carbon-to-product conversion, but little is known about these bioprocesses at a systems level. Production of the unnatural metabolite citramalate in Escherichia coli requires the expression of a single gene coding for citramalate synthase. Multiomic analyses of a fermentation producing 25 g liter1 citramalate were undertaken to uncover the reasons for its productivity. Metabolite, transcript, protein, and lipid profiles of high-cell-density, fed-batch fermentations of E. coli expressing either citramalate synthase or an inactivated enzyme were similar. Both fermentations showed downregulation of flagellar genes and upregulation of chaperones IbpA and IbpB, indicating that these responses were due to recombinant protein synthesis and not citramalate production. Citramalate production did not perturb metabolite pools, except for an increased intracellular pyruvate pool. Gene expression changes in response to citramalate were limited; none of the general stress response regulons were activated. Modeling of transcription factor activities suggested that citramalate invoked a GadW-mediated acid response, and changes in GadY and RprA regulatory small RNA (sRNA) expression supported this. Although changes in membrane lipid composition were observed, none were unique to citramalate production. This systems analysis of the citramalate fermentation shows that E. coli has capacity to readily adjust to the redirection of resources toward recombinant protein and citramalate production, suggesting that it is an excellent chassis choice for manufacturing organic acids. IMPORTANCE Citramalate is an attractive biotechnology target because it is a precursor of methylmethacrylate, which is used to manufacture Perspex and other high-value products. Engineered E. coli strains are able to produce high titers of citramalate, despite having to express a foreign enzyme and tolerate the presence of a nonnative biochemical. A systems analysis of the citramalate fermentation was undertaken to uncover the reasons underpinning its productivity. This showed that E. coli readily adjusts to the redirection of metabolic resources toward recombinant protein and citramalate production and suggests that E. coli is an excellent chassis for manufacturing similar small, polar, foreign molecules.We thank the Biotechnology and Biological Sciences Research Council UK and InnovateUK for funding (Industrial Biotechnology Catalyst BB/N01040X/1) and the Centre of Excellence in Mass Spectrometry funded by Science City York (Yorkshire Forward, EP/K039660/1, EP/M028127/1)

Development of selective agonists and antagonists of P2Y receptors

Although elucidation of the medicinal chemistry of agonists and antagonists of the P2Y receptors has lagged behind that of many other members of group A G protein-coupled receptors, detailed qualitative and quantitative structure–activity relationships (SARs) were recently constructed for several of the subtypes. Agonists selective for P2Y1, P2Y2, and P2Y6 receptors and nucleotide antagonists selective for P2Y1 and P2Y12 receptors are now known. Selective nonnucleotide antagonists were reported for P2Y1, P2Y2, P2Y6, P2Y11, P2Y12, and P2Y13 receptors. At the P2Y1 and P2Y12 receptors, nucleotide agonists (5′-diphosphate derivatives) were converted into antagonists of nanomolar affinity by altering the phosphate moieties, with a focus particularly on the ribose conformation and substitution pattern. Nucleotide analogues with conformationally constrained ribose-like rings were introduced as selective receptor probes for P2Y1 and P2Y6 receptors. Screening chemically diverse compound libraries has begun to yield new lead compounds for the development of P2Y receptor antagonists, such as competitive P2Y12 receptor antagonists with antithrombotic activity. Selective agonists for the P2Y4, P2Y11, and P2Y13 receptors and selective antagonists for P2Y4 and P2Y14 receptors have not yet been identified. The P2Y14 receptor appears to be the most restrictive of the class with respect to modification of the nucleobase, ribose, and phosphate moieties. The continuing process of ligand design for the P2Y receptors will aid in the identification of new clinical targets

Sewage Disposal and Viral Pollution of the Ottawa River

Abstract The quality of water in the Ottawa River is being affected by the disposal of increased volumes of sewage into it. Some of the sewage disposal points are situated upstream of beaches and intake points for water purification plants. The aim of this study was to assess the impact of such waste disposal on the virological quality of recreational and drinking waters for the Ottawa area. A total of 132 weekly samples of raw sewage, chlorinated secondary effluents, raw and finished surface waters were examined for viruses from June to December 1977. In addition to these, ten samples of tap water, collected during the first two weeks of April 1978, were also included in this study. Virus concentration from these samples was carried out using the talc-Celite technique developed in the laboratory. Primary human embryonic kidney (HEK) cells and BS-C-1 cells were used for the detection and quantitation of viruses present in the sample concentrates. Virus isolates were identified by their cytopathology, examination under the electron microscope and serology. When 6 1. volumes were processed, nearly all the samples of raw sewage and 54% chlorinated effluent samples were found to be positive for virus. Approximately 50% of the surface water samples were also shown to contain virus using 40 1. sample volumes. Concentrates of some of the potable water samples showed virus-like degeneration in cell cultures. Although this degeneration was found to be transmissible, at this stage it is not possible to say if this effect was in fact due to a viral agent. The following major conclusions were drawn from this study: (a) All three major enteric virus groups were represented in the virus isolates. However, inherent limitations of sample concentration and virus isolation techniques may have resulted in the detection of only a small fraction of the viruses present in the samples. (b) There was no apparent correspondence between the numbers of indicator bacteria and the presence or absence of detectable virus in the samples. (c) Viruses detected in the recreational and raw water samples may be due to the presence of point sources of raw sewage discharge upstream. This could result in the dissemination of human pathogenic viruses through recreational and potable waters.</jats:p