Development of a PCR protocol for the detection of Escherichia coli O157:H7 and Salmonella spp. in surface water

Escherichia coli O157:H7 and Salmonella are pathogenic microorganisms that can cause severe gastrointestinal illness in humans. These pathogens may be transmitted in a variety of ways, including food and water. The presence of Salmonella and E. coli O157:H7 in surface waters constitutes a potential threat to human health when used for either drinking or recreation. As with most waterborne pathogens, Salmonella and E. coli O157:H7 are difficult to detect and enumerate with accuracy in surface waters due to methodological limitations. The aim of this study was to develop a protocol for the detection of Salmonella spp., E. coli O157:H7 and E. coli virulence genes (stx ₁, stx ₂ and eae) in water using a single enrichment step and PCR. In spiked water samples, PCR results showed high sensitivity (<3 CFU/L) for both microorganisms. The protocol developed in this study has been applied in different surface waters in association with microbiological and physical analysis. The frequency of PCR positive samples was 33% for Salmonella and 2% for E. coli O157:H7 producing intimin (eae) and Shiga-like toxin I (stx ₁). Moreover, the finding of amplicons corresponding to eae and stx ₁ genes in the absence of E. coli O157:H7 suggested the possible presence of other pathogenic bacteria that carry these genes (e.g. EHEC, Shigella strains). The results obtained showed that the developed protocol could be applied as a routine analysis of surface water for the evaluation of microbiological risks.     

The value of rapid damage assessment for efficient earthquake response

Every year earthquakes cause substantial economic losses and loss of life in many parts of the world. Earth observations may provide valuable information on spatial damage distribution and through that increase the efficiency of rapid response actions, finally resulting in reduction of earthquake induced losses. However, a methodology for quantitative assessment of the potential value of information in such a context has not yet been developed. That knowledge would be of high importance for planning and development of Earth observation systems on both regional and international levels when aiming at sustainable development goals. In this paper we suggest a stochastic modeling approach to assess the value of information for earthquake rapid response. Our analysis is focused on a rather short time interval after an earthquake occurrence (order of several hours) when there is a maximum need for urgent help to the earthquake victims. We use rescue efficiency as a performance measure of earthquake response actions; this efficiency is described in terms of timely arrival of rescue teams at places, where their help is mostly needed. We quantify the benefit of using spatial damage distribution information in terms of cost reduction/rescue efficiency gains. We intentionally conduct our analysis at a methodological level and do not go deeper into case studies to keep general conclusions traceable. The modeling exercise we present in the paper is a first step towards a more detailed and integrated approach that could contribute to better systematic understanding of earthquake response actions and ultimately improve their efficiency.     

Mechanistic insights into acetaminophen removal on cashew nut shell biomass-derived activated carbons

Environmental Science and Pollution Research - Activated carbons prepared from cashew nut shells by chemical activation with phosphoric acid were tested for the removal of acetaminophen. It was...     

The impact of tourism on municipal solid waste generation: The case of Menorca Island (Spain)

Tourism can sustain high levels of employment and income, but the sector is a source of environmental and health impacts. One of the most important is the generation of municipal solid waste (MSW). However, there is a lack of studies which quantify how much the tourist population engages in total MSW and separately collected recyclables. The aim of this paper is to estimate the impact of the tourist population on MSW, both total and separately collected, for the period 1998–2010, for the Mediterranean island of Menorca (Spain). We use dynamic regressions models, including data for monthly stocks of tourists. The results show that, on average, a 1% increase in the tourist population in Menorca causes an overall MSW increase of 0.282% and one more tourist in Menorca generates 1.31 kg day^?1 (while one more resident generates 1.48 kg day^?1). This result could be useful to better estimate the seasonal population of different regions, since intrannual fluctuation of MSW is used as a proxy measure of actual population (the sum of residents and tourists). Moreover, an increase of 1% in the tourist population causes an increase of 0.232% in separately collected recyclables and an additional tourist generates 0.160 kg day^?1. One resident selectively collects on average 47.3% more than one tourist. These results can help in the planning of waste infrastructure and waste collection services in tourist areas.     

Greenhouse gases accounting and reporting for waste management – A South African perspective

This paper investigates how greenhouse gases are accounted and reported in the waste sector in South Africa. Developing countries (including South Africa) do not have binding emission reduction targets, but many of them publish different greenhouse gas emissions data which have been accounted and reported in different ways. Results show that for South Africa, inventories at national and municipal level are the most important tools in the process of accounting and reporting greenhouse gases from waste. For the development of these inventories international initiatives were important catalysts at national and municipal levels, and assisted in developing local expertise, resulting in increased output quality. However, discrepancies in the methodology used to account greenhouse gases from waste between inventories still remain a concern. This is a challenging issue for developing countries, especially African ones, since higher accuracy methods are more data intensive. Analysis of the South African inventories shows that results from the recent inventories can not be compared with older ones due to the use of different accounting methodologies. More recently the use of Clean Development Mechanism (CDM) procedures in Africa, geared towards direct measurements of greenhouse gases from landfill sites, has increased and resulted in an improvement of the quality of greenhouse gas inventories at municipal level.     

Chloromuconolactone dehalogenase ClcF of actinobacteria

This work investigated the distribution of the clcF gene in actinobacteria isolated from different ecotopes. The gene encodes chloromuconolactone dehalogenase (CMLD) ClcF, the enzyme found to date in only one representative of Gram‐positive bacteria, Rhodococcus opacus 1CP, adapted to 2‐chlorophenol (2CP). Using primers specific to the clcF gene, from the DNA matrix of rhodococcal strains closely related to species Rhodococcus wratislaviensis (P1, P12, P13, P20, G10, KT112, KT723, BO1) we obtained PCR products whose nucleotide sequences were 100% identical to that of the clcF gene from strain R. opacus 1CP. CMLDs isolated from the biomass of strains Rhodococcus spp. G10 and P1 grown on 2CP did not differ by their subunit molecular mass deduced from the known amino acid sequence of the clcF gene from the ClcF of strain R. opacus 1CP. Matrix‐assisted laser dissociation/ionization time‐of‐flight mass spectrometry showed the presence of a peak with m/z 11,194–11,196 Da both in whole cells and in protein solutions with a ClcF activity. Thus, we have first time shown the distribution of ClcF among actinobacteria isolated from geographically distant habitats.     

Triadimefon Causes Branchial Arch Malformations in Xenopus laevis Embryos (5 pp)

- DOI: http://dx.doi.org/10.1065/espr2006.01.014 Background, Aims and Scope Triazole-derivatives are potent antifungal agents used as systemic agricultural fungicides and against fungal diseases in humans and domestic animals. They act by inhibiting the cytochrome P-450 conversion of lanosterol to ergosterol, thus resulting in faulty fungal cell wall synthesis. Some data have been published about the teratogenic activity of triazoles on rodent embryos: Hypoplasias, abnormal shape, agenesis of the branchial arches, for example, were reported as typical induced malformations. Unfortunately, no data are available on the embryotoxicity of these compounds in amphibians, despite the increasing concern among the scientific community about the phenomenon of global amphibian population declines. The aim of the present work is to evaluate the embryo-lethal and teratogenic potentials of Triadimefon (FON), a triazolederivative widely used as an antimycotic in agriculture, by the test FETAX (Frog Embryos Teratogenic Assay, Xenopus) with particular attention being paid to the analysis of branchial arch malformations. Methods Xenopus laevis embryos were exposed continuously from stage 9 to increasing concentrations of FON and analyzed at stage 47 for mortality and teratogenicity (group I) to determine the median lethal (LC50) and teratogenic (TC50) concentrations. Another two pools of larvae were exposed to FON for a 2 hour period at early gastrula (Group II) or neurula (Group III) stages to verify which period of development is the most sensitive to FON. The malformations observed were further investigated by histological section and cartilage staining with Alcian blue. Results and Discussion The assay has estimated LC50 and TC50 values of 63.8 μM and 2.73 μM, respectively; the resulting TI (Teratogenic Index = LC50/TC50) value of 23.4 has underlined the very high teratogenic risk associated with this compound. Neurulation was more sensitive to FON exposure than gastrulation, since the TC50 estimated values for group III (neurula exposed) specimens was 7.6 times lower than those of group II (gastrula exposed). Interestingly, for each group analyzed, 100% of malformed embryos showed alterations at branchial arch derived cartilages: Anterior cartilages were reduced, missing, fused or incorrectly positioned while gill cartilages were altered only in the most severely affected specimens. In some cases these malformations were associated with hyperpigmentation. Our results support the hypothesis that FON can interfere with Neural Crest Cell (NCC) migration, since craniofacial components and melanophores are derived from neural crest material. Conclusion In conclusion, our data show Triadimefon to be a potent teratogen able to induce specific craniofacial malformation in Xenopus laevis embryos, probably interfering with the NCC migration into the branchial mesenchyme. These results are also interesting for ecotoxicological reasons as FON, as well as other pesticides, are likely to be present in water systems near agricultural or urban areas which may serve as habitats for developing amphibians and fishes. Recommendation and Outlook Our results are in agreement with the data obtained on in vitro cultured rat embryos suggesting that the FON mechanism of action involves strongly conserved molecules. The choice of Xenopus laevis as the model organism allows us to extend the toxicological and teratological observations to a molecular level, in order to search for novel genes regulated by FON exposure.     

The existence of optimal strategy in the exploitation of limited biocenoses

Optimal strategy in the control of multicomponent biocenoses that are described adequately by an autonomous discrete model has been investigated. It is shown that for any such biocenosis there exists at least one stationary optimal strategy in terms of discounted reward. The optimal strategy is described for communities of competing species, together with the method of its derivation.