Assessment of the bacterial community structure in a Brazilian clay soil treated with atrazine

In the present paper, the bacterial communities in two soils, one from an agricultural sugarcane cropped field and the other from an unperturbed soil with similar geopedological characteristics, were characterized using the Fluorescence In Situ Hybridization (FISH) method. FISH consists of in situ identification of bacteria using fluorescent labeled 16S rRNA targeted oligonucleotide probes visualizable under epifluorescence microscope. In the cultivated soil, in line with agricultural practice, the pre-emergence herbicide atrazine had been regularly applied each year at a concentration of 5 L/ha. The Shannon Diversity and Evenness Indices were also calculated using the phylogenetic data obtained from the FISH analysis. Although, at the sampling time (6 months after soil atrazine treatment), no residual herbicide concentration was found, the overall bacterial community results show a lower diversity and evenness in the agricultural soil than in the unperturbed one, demonstrating how microbiological indicators are sensitive to anthropogenic disturbance. In the natural soil, the dominant groups were α-Proteobacteria, β-Proteobacteria, and γ-Proteobacteria (representing more than 50 % of the bacteria), but in the agricultural soil, their abundance decreased significantly and represented just 31 % of the bacteria domain

Germination, root elongation, and photosynthetic performance of plants exposed to sodium lauryl ether sulfate (SLES). An emerging contaminant

The anionic surfactant SLES (sodium lauryl ether sulfate) is an emerging contaminant, being the main component of foaming agents that are increasingly used by the tunnel construction industry. To fill the gap of knowledge about the potential SLES toxicity on plants, acute and chronic effects were assessed under controlled conditions. The acute ecotoxicological test was performed on Lepidum sativum L. (cress) and Zea mays L. (maize). Germination of both species was not affected by SLES in soil, even at concentrations (1200 mg kg−1) more than twice higher than the maximum realistic values found in contaminated debris, thus confirming the low acute SLES toxicity on terrestrial plants. The root elongation of the more sensitive species (cress) was instead reduced at the highest SLES concentration. In the chronic phytotoxicity experiment, photosynthesis of maize was downregulated, and the photosynthetic performance (PITOT) significantly reduced already under realistic exposures (360 mg kg−1), owing to the SLES ability to interfere with water and/or nutrients uptake by roots. However, such reduction was transient, likely due to the rapid biodegradation of the surfactant by the soil microbial community. Indeed, SLES amount decreased in soil more than 90% of the initial concentration in only 11 days. A significant reduction of the maximum photosynthetic capacity (Pnmax) was still evident at the end of the experiment, suggesting the persistence of negative SLES effects on plant growth and productivity. Overall results, although confirming the low phytotoxicity and high biodegradability of SLES in natural soils, highlight the importance of considering both acute and nonlethal stress effects to evaluate the environmental compatibility of soil containing SLES residues

Use of microbial fuel cells for soil remediation. A preliminary study on DDE

DDE (2,2-bis (p-chlorophenyl)-1,1-dichloroetylene) is a very persistent and bioaccumulative pesticide and its residues are continuously found in the environment. Among the green remediation strategies for soil recovery, terrestrial Microbial Fuel Cells (MFC) are arousing great interest in scientific community. MFCs transform energy stored in the chemical bonds of organic compounds into electrical energy thanks to exo-electrogen microorganisms naturally occurring in soil, which catalyse oxidation and reduction reactions in the area between two graphite electrodes. This work reports preliminary data on the use of MFCs for promoting soil decontamination from DDE. Several experimental conditions (e.g. addition of compost and open/closed circuit) were applied for assessing how to improve MFC performance in favouring DDE removal. MFCs promoted a significant DDE removal (39%) after 2 months, while at the same time any pesticide decrease was observed in the batch condition. Compost addition stimulated microbial activity and improved MFC performance for a longer time

Groundwater Autochthonous Microbial Communities as Tracers of Anthropogenic Pressure Impacts: Example from a Municipal Waste Treatment Plant (Latium, Italy)

The groundwater behavior at a municipal solid waste disposal dump, located in Central Italy, was studied using a multi-parameter monitoring over 1 year consisting of 4 seasonal samples. The hydrological and hydrogeological dynamics of water circulation, microbiological parameters (microbial abundance and cell viability of the autochthonous microbial community), dissolved organic carbon, and several contaminants were evaluated and related to the geological structures in both two and three dimensions and used for geostatistical analysis in order to obtain 3D maps. Close relationships between geological heterogeneity, water circulation, pollutant diffusion, dissolved organic carbon, and cell viability were revealed. The highest cell viability values were found with dissolved organic carbon (DOC) values ≤0.5 mg/L; above this value, DOC negatively affected the microbial community. The highest DOC values were detected in groundwater at some sampling points within the site indicating its probable origin from the waste disposal dump. Although legislation limits for the parameters measured were not exceeded (except for a contaminant in one piezometer), the 1-year multi-parameter monitoring approach made it possible to depict both the dynamics and the complexity of the groundwater flux and, with "non-legislative parameters" such as microbial cell viability and DOC, identify the points with the highest vulnerability and their origin. This approach is useful for identifying the most vulnerable sites in a groundwater body

A new fluorescent oligonucleotide probe for in-situ identification of Microcystis aeruginosa in freshwater.

contaminated water bodies (freshwater, brackish and marine areas). Among 150 known cyanobacteria genera,>40 species are able to produce toxins, which are natural compounds that differ from both a chemical and toxicological point of view and are responsible for acute and chronic poisoning in animals and humans. Among the main classes of cyanotoxins, microcystins are frequently found in the environment. Fast and accurate methods for unequivocally identifying microcystin-producing cyanobacteria, such as Microcystis aeruginosa in water bodies, are necessary to distinguish them from other non-toxic cyanobacteria and to manage and monitor algal blooms. For this purpose, we designed, developed and validated an oligonucleotide probe for FISH (Fluorescence In Situ Hybridization) analysis to detect Microcystis aeruginosa at the species level even at relatively low concentrations in freshwater. The FISH probe, MicAerD03, was designed using the ARB software with the Silva database within the framework of the MicroCoKit project, also with the intention of adding it to the microarray from the EU project, μAQUA, for freshwater pathogens, which had only genus level probes for Microcystis. We tested various fixative methods to minimize the natural autofluorescence from chlorophyll-a and certain accessory pigments (viz., phycobilins and carotenoids). The FISH probe was tested on pure cultures of Microcystis aeruginosa, and then successfully applied to water samples collected from different sampling points of the Tiber River (Italy), using a laser confocal microscope. Subsequently, the probe was also conjugated at the 5′ end with horse-radish peroxidase (HRP-MicAerD03) to apply the CAtalysed Reported Deposition-FISH (CARD-FISH) for increasing the fluorescence signal of the mono-fluorescently labelled probe and make it possible to detect M. aeruginosa using an epifluorescence microscope. Samples taken within the EU MicroCokit project indicated thatmicroarray signals for Microcystis were coming from single cells and not colonial cells. We confirmed this with the CARD-FISH protocol used here to validate the microarray signals for Microcystis detected at the genus level in MicroCokit. This paper provides a new early warning tool for investigating M. aeruginosa at the species level even at low cell concentrations in surface water, which can be added to the μAqua microarray for all freshwater pathogens to complete the probe hierarchy for Microcystis aeruginosa

Celle a combustibile microbiche terrestri: uno strumento efficace nel recupero di suoli contaminati e nella produzione di energia.

Una cella a combustibile microbica (MFC) è un sistema bio-elettrochimico che utilizza un microrganismo attivo come biocatalizzatore per la produzione di elettricità. Essa è costituita da due comparti, uno anodico ed uno catodico, separati da una membrana di scambio protonico. L’energia chimica di legame, disponibile grazie alla presenza di un substrato biodegradabile, viene trasformata direttamente in energia elettrica per azione microbica, che catalizza la rimozione degli elettroni dal substrato. I batteri presenti nella camera anodica, o comunque nel mezzo in cui è immerso l’anodo, sono in grado di convertire un’enorme varietà di substrati organici (acetato, glucosio, cellulosa, reflui di varia origine, contaminanti organici) in CO2, acqua ed energia. Tra le MFC, le Celle a Combustibile Microbiche Terrestri (Terrestrial Microbial Fuel Cells - TMFC), hanno come elettrolita il suolo. Esso è una matrice molto più complessa rispetto all’acqua, variando nella composizione granulometrica, nella capacita di ritenzione idrica, nella capacità di scambio cationico, nonché nella distribuzione dei contaminanti; pertanto le TMFC sono dei dispositivi di cui è ancora necessario esplorare tutte le potenzialità di applicazione per il recupero di suoli contaminati

Biodegradation of herbicide diuron by streptomycetes isolated from soil

The diuron degrading activity of 17 streptomycete strains, obtained from agricultural and non-agricultural soils, was determined in the laboratory. All strains were identified as Streptomyces sp. by phenotypic characteristics and PCR-based assays. The strains were cultivated in liquid medium with diuron (4mgL(-1)) at 25 degrees C for 15 days. Biodegradation activity was deter-mined by high-performance liquid chromatography. The results indicated that all strains were able to degrade diuron, but to different amounts. Twelve strains degraded the herbicide by up to 50% and four of them by up to 70%. Strain A7-9, belonging to S. albidoflavus cluster, was the most efficient organism in the degradation of diuron, achieving 95% degradation after five days of incubation and no herbicide remained after 10 days. Overall, the strains isolated from agricultural soils exhibited higher degradation percentages and rates than those isolated from non-agricultural soils. Given the high degradation activity observed here, the streptomycete strains show a good potential for bioremediation of soils contaminated with diuron. (c) 2006 Elsevier Ltd. All rights reserved.Castillo López, MÁ.; Felis Reig, N.; Aragón Revuelta, P.; Cuesta Amat, G.; Sabater Marco, C. (2006). Biodegradation of herbicide diuron by streptomycetes isolated from soil. International Biodeterioration and Biodegradation. 58(3-4):196-202. doi:10.1016/j.ibiod.2006.06.020S196202583-

Pesticide risk assessment and management in a globally changing world—report from a European interdisciplinary workshop

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA [Axe_IRSTEA]DTAM-QT2-ADAPTATION [TR2_IRSTEA]ARCEAU [TR2_IRSTEA]DTAMGlobal climate change will affect worldwide agriculture in many ways. The anticipated or already occurring changes raise concerns about the sustainability of production and the ability of agriculture to feed human populations. This appeals to sustainable agriculture providing ecosystem services more efficiently than today, and accordingly to substantial evolutions of pesticide risk assessment (RA) and risk management (RM). The RA/RM issues were discussed by two European research networks in a 2011 workshop. The RA-RM-monitoring conceptual cycle tends to be virtual, with poor connections between certain steps. The design of more comprehensive emissions scenarios could improve the accuracy of predicted runoff transport, while the microcosm/mesocosm approach could help establish causal relationships between fate / exposure and populations / communities. Combined with ecological modelling, effects can be extrapolated to higher spatial and temporal scales. Risk management of diffuse sources should be designed simultaneously at the watershed and individual plot scales. Monitoring is key to assessing the effectiveness of risk reduction measures reduce and evaluate the overall quality of the aquatic compartment. More flexible monitoring strategies clearly linked to RM decisions are therefore needed. Although some technical questions remain, it is time to apply passive samplers more routinely. A set of research and development needs covering the whole RA/RM cycle is listed in conclusion

Screening of benzodiazepines in thirty European rivers

Pharmaceuticals as environmental contaminants have received a lot of interest over the past decade but, for several pharmaceuticals, relatively little is known about their occurrence in European surface waters. Benzodiazepines, a class of pharmaceuticals with anxiolytic properties, have received interest due to their behavioral modifying effect on exposed biota. In this study, our results show the presence of one or more benzodiazepine(s) in 86% of the analyzed surface water samples (n = 138) from 30 rivers, representing seven larger European catchments. Of the 13 benzodiazepines included in the study, we detected 9, which together showed median and mean concentrations (of the results above limit of quantification) of 5.4 and 9.6 ng L−1, respectively. Four benzodiazepines (oxazepam, temazepam, clobazam, and bromazepam) were the most commonly detected. In particular, oxazepam had the highest frequency of detection (85%) and a maximum concentration of 61 ng L−1. Temazepam and clobazam were found in 26% (maximum concentration of 39 ng L−1) and 14% (maximum concentration of 11 ng L−1) of the samples analyzed, respectively. Finally, bromazepam was found only in Germany and in 16 out of total 138 samples (12%), with a maximum concentration of 320 ng L−1. This study clearly shows that benzodiazepines are common micro-contaminants of the largest European river systems at ng L−1 levels. Although these concentrations are more than a magnitude lower than those reported to have effective effects on exposed biota, environmental effects cannot be excluded considering the possibility of additive and sub-lethal effects