Comparison of Coliforms and Coliphages as Tools for Assessment of Viral Contamination in River Water

The aim of the study was to evaluate the presence of pathogenic viruses in the Moselle River and to compare the usefulness of thermotolerant coliforms and somatic coliphages as tools for river water quality assessment in terms of viral contamination. Thermotolerant coliforms and somatic coliphages were enumerated by standardized methods in 170 samples of river water drawn from five sampling sites along the Moselle River (eastern France). BGM cell culture and integrated cell culture-reverse transcription-PCR DNA enzyme immunoassay were used to determine the presence of pathogenic viral genome (Enterovirus and Norovirus genogroup II [GGII]) and infectious Enterovirus spp. in 90 1-liter samples. No infectious Enterovirus spp. were isolated, but Enterovirus and Norovirus GGII genomes were detected in 38% of the samples. Norovirus GGII genome was mostly detected in winter, whereas Enterovirus genome was mostly detected in summer and fall. Somatic coliphages appeared to be less sensitive to higher river water temperature than thermotolerant coliforms. Furthermore, the number of river water samples positive for pathogenic viral genome increased with increasing concentration of somatic coliphages, whereas coliform concentration was unrelated to viral genome contamination. Consequently somatic coliphages, which are less sensitive to environmental factors than thermotolerant coliforms in river water, would provide a promising tool for assessment of river water quality in terms of fecal and viral pollution

Survival of infectious Poliovirus-1 in river water compared to the persistence of somatic coliphages, thermotolerant coliforms and Poliovirus-1 genome

International audienceThe microbiological quality of water is currently assessed by search for fecal bacteria indicators. There is, however, a body of knowledge demonstrating that bacterial indicators are less resistant to environmental factors than human pathogenic viruses and therefore underestimate the viral risk. As river water is often used as a resource for drinking water production, it is particularly important to obtain a valid estimation of the health hazard, including specific viral risk. This work was conducted to compare the survival of infectious Poliovirus-1 used as a pathogenic virus model to the persistence of, on the one hand, thermotolerant coliforms commonly used as indicators and on the other hand, to somatic coliphages and Poliovirus-1 genome considered as potential indicators. We studied the behavior of infectious Poliovirus-1 and the three (potential) indicators of viral contamination in river water at three different temperatures (4°C,18°C and 25°C). This experiment was performed twice with river water sampled at two different periods, once in winter and once in summer. Our results showed that the survival of thermotolerant coliforms can be 1.5-fold lower than infectious Poliovirus-1. In contrast, under all our experimental conditions, somatic coliphages and Poliovirus-1 genome persisted longer than infectious Poliovirus-1, surviving, respectively, 2–6-fold and about 2-fold longer than infectious Poliovirus-1. According to our results exclusively based on survival capacity, somatic coliphages and viral genome, unlike thermotolerant coliforms appear to be better indicators of viral contamination in river water. Moreover, the disappearance of viral genome is well-correlated to that one of infectious virus irrespective of the conditions tested

Development of a viral concentration method for bottled water stored in hydrophobic support

International audienceSeveral protocols have been described for the detection of genomes of enteric viruses from water using two-step procedures: membrane filtration and RT-PCR detection. However, these methods, when applied to bottled water, generally consider only the aqueous phase. Such procedures do not take into account the adhesion of viruses onto the hydrophobic container. Potential adhesion results in loss of viral concentration in the aqueous phase and consequently viral pollution is underestimated in such a system. A procedure based on the addition of surfactant to elute viruses followed by membrane concentration was developed to avoid this underestimation. Firstly, using poliovirus 1 as a model, this study demonstrated that the best solution to recover virus and/or viral genome is a mix of sodium dodecyl sulphate, a nonionic detergent and guanidine thiocyanate. Furthermore, temperature has a significant but low effect on elution. A positively charged 0.2 μm inorganic membrane composed of Alumina (Anodisc, Whatman) is also the best membrane to concentrate viral material before the detection by RT-PCR. Finally, the developed protocol gives significantly higher poliovirus 1 recovery rate than a reference protocol previously described (aqueous phase concentration on Zetapore). The difference can be explained by the recovery of the viruses adsorbed onto the water container

X-ray reflectometry and grazing-incidence X-ray fluorescence characterization of innovative electrodes for tantalum-based resistive random access memories

17th International Conference on Total Reflection X-Ray Fluorescence Analysis and Related Methods (TXRF)Location: Brescia, ITALYDate: SEP 19-22, 2017International audienceWe evaluate the ability of the combination of grazing-incidence X-ray fluorescence (GIXRF) with X-ray reflectometry (XRR) to probe the impact of variations in the deposition process of tantalum oxide on the chemical depth-profiles of Ta2O5/metal structure, titanium nitride and nickel being investigated as bottom electrode material as they are good candidates for the replacement of noble materials by low-cost fab-friendly abundant electrodes for Resistive RAM. TOF-SIMS and GIXRF/XRR both unambiguously demonstrate the significant TiN-Ta intermixing in Ta2O5/TiN stacks, even with optimized Ta2O5 process conditions. On the contrary, TOF-SIMS profiles reveal that the introduction of H* plasma step in PE-ALD Ta2O5 process drastically reduces both the oxidation of nickel electrode material and the Ta2O5/Ni intermixing, therefore confirming that nickel is a good candidate for Ta2O5 based ReRAM. The influence of H* plasma on nickel-based samples was also evidenced by GIXRF/XRR technique, first qualitatively, then quantitatively by the use of model-based multilayer combined analysis, therefore demonstrating the performances of GIXRF/XRR as highly-sensitive, non-destructive chemical depth-profile technique suitable to support process development, either in lab or even in fabs

Quasi insitu XPS characterization applied to PEALD selective deposition of TiO2 The IMPACT 300mm project and platform: merging academic research and industrial applications in microelectronic

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Etude par XPS « quasi insitu » de la croissance sélective de couches de TiO2

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TMD film growth studied by quasi-insitu XPS on a 300mm silicon wafer

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