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The degradation and bioaccumulation of selected antibiotics such as the sulfonamide sulfamethoxazole (SMX) and the fluoroquinolones enrofloxacin (ENR) and ciprofloxacin (CIP) were investigated in soil microcosm experiments where Lactuca sativa was grown with manure or digestate (1%) and spiked with a mixture of the three antibiotics (7.5 mg/kg each). The soil, rhizosphere and leaf phyllosphere were sampled (at 0 and 46 days) from each microcosm to analyze the antibiotic concentrations, main resistance genes (sul1, sul2, qnrS, aac-(6')-Ib-crand qepA), the intI1and tnpA mobile genetic elements and the microbial community structure.Overall results showed that SMX and CIP decreased (70-85% and 55-79%, respectively), and ENR was quite persistent during the 46-day experiment. In plant presence, CIP and ENR were partially up-taken from soil to plant. In fact the bioaccumulation factors were1, with higher values in manure than digestate amended soils. The most abundant gene in soil was sul2 in digestate- and aac-(6')-Ib-cr in the manure-amended microcosms. In soil, neither sulfamethoxazole-resistance (sul1 and sul2), nor fluoroquinolone-resistance (aac-(6')-Ib-cr, qepA and qnrS) gene abundances were correlated with any antibiotic concentration. On the contrary, in lettuce leaves, the aac-(6')-Ib-cr gene was the most abundant, in accordance with the fluoroquinolone bioaccumulation. Finally, digestate stimulated a higher soil microbial biodiversity, introducing and promoting more bacterial genera associated with antibiotic degradation and involved in soil fertility and decreased fluoroquinolone bioaccumulation.

Current regulation on the authorization of plant protection products (PPPs) in the European Union is limited to the evaluation of ecological risks for the single active substances they contain. However, plant protection treatments in agriculture often consist of PPPs already containing more than one active substance; moreover, each cropped field receives multiple applications per year, leading to complex pesticide mixtures in the environment. Different transport processes lead to a multitude of heterogeneous and potentially toxic substances that, for example, may reach water bodies and act simultaneously on natural freshwater ecosystems. In this context, the development of methodologies and tools to manage risks of pesticides mixtures is imperative to improve the current ecological risk assessment procedures and to avoid further deterioration of ecological quality of natural resources. The present study suggests new procedures for identifying pesticide mixtures of potential concern released from agricultural crops in surface water. The approach follows the European Union regulatory context for the authorization of PPPs in the market (edge-of field risk assessment) and requires the use of Forum for the Co-ordination of pesticide fate models and their Use (FOCUS) models (Step 3 and 4) for calculating the concentrations in surface water of mixture components on a daily basis. Moreover, it uses concentration addition models to calculate the toxic potency of the pesticide mixtures released by a treated crop. To implement this procedure, we developed a simple Microsoft-Excel-based tool. We also considered two case studies (maize and apple tree), representative of Italian agricultural scenarios for annual and perennial crops. Moreover, we compared results with 3 years of monitoring data of surface water bodies of the Lombardia region (northern Italy) where the two crops are largely present. Environ Toxicol Chem 2022;41:2028-2038. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Electroactive bacteria (EAB) are natural microorganisms (mainly Bacteria and Archaea) living in various habitats (e.g., water, soil, sediment), including extreme ones, which can interact electrically each other and/or with their extracellular environments. There has been an increased interest in recent years in EAB because they can generate an electrical current in microbial fuel cells (MFCs). MFCs rely on microorganisms able to oxidize organic matter and transfer electrons to an anode. The latter electrons flow, through an external circuit, to a cathode where they react with protons and oxygen. Any source of biodegradable organic matter can be used by EAB for power generation. The plasticity of electroactive bacteria in exploiting different carbon sources makes MFCs a green technology for renewable bioelectricity generation from wastewater rich in organic carbon. This paper reports the most recent applications of this promising technology for water, wastewater, soil, and sediment recovery. The performance of MFCs in terms of electrical measurements (e.g., electric power), the extracellular electron transfer mechanisms by EAB, and MFC studies aimed at heavy metal and organic contaminant bioremediationF are all described and discussed.

Bioremediation technologies are useful and sustainable solutions for recovering pollutants from ecosystems. In particular, the plant-assisted bioremediation or phyto-assisted bioremediation (PABR) strategy, relying on the synergistic actions between plant root system and natural microorganisms (bacteria and fungi), can be effective for stabilizing, storing, and degrading contaminants of polluted soils. Plant species through release of root exudates can stimulate biodegradation activity of natural soil microorganisms in the rhizosphere. The use of organic amendments (e.g., biochar, compost) in PABR applications can also be useful for enhancing plant growth, soil quality and increase the biodegradation of some contaminants. Moreover, PABR technology produces biomass, a by-product, which can be profitably valorised for producing energy in line with a circular economy. Deeper investigations on the overall processes in order to improve PABR effectiveness and ensure its zero impact on environment are desirable.

Hydrocarbons occur in fossil fuels such as crude oil and consist mainly of hydrogen and carbon. Although they are natural chemicals, crude oil refining results in commercial products with new physico-chemical properties, which can increase their complexity and toxicity, and hamper their degradation. The presence of biodiverse natural microbial communities is a prerequisite for an effective homeostatic response to the various hydrocarbons, that contaminate ecosystems. However, their removal depends on the compartment contaminated (water, sediment, soil), their molecular weight, and their toxicity not hampering microbial activity. This paper reports different bacterial species involved in the biodegradation of aliphatic and aromatic hydrocarbons. Hydrocarbon contamination is generally due to the co-presence of a mixture of these chemicals, and their removal from the environment cannot rely on only a single species but generally requires bacterial consortia. Versatile bacterial metabolism relies on specific genes encoding the key enzymes involved in the peripheral metabolic and central metabolic pathways for degrading aliphatic and polycyclic aromatic hydrocarbons. Although microbial metabolism can have the potential for natural attenuation of these contaminants, hydrocarbon bioremediation, through biostimulation (e.g., use of surfactants, plants, earthworms, and nanoparticles) and bioaugmentation, can be a valid tool for removing them from actually contaminated soil, freshwater, groundwater, and seawater.

8 páginas.- 6 figuras.- 40 referencias, The risks of pollution by polycyclic aromatic hydrocarbons (PAHs) may increase in bioremediated soils as a result of the formation of toxic byproducts and the mobilization of pollutants associated to suspended colloids. In this study, we used the motile and chemotactic bacterium Pseudomonas putida G7 as an experimental model for examining the potential role of bacterial motility in the cometabolism and biosorption of pyrene in a porous medium. For this purpose, we conducted batch and column transport experiments with 14C-labelled pyrene loaded on silicone O-rings, which acted as a passive dosing system. In the batch experiments, we observed concentrations of the 14C-pyrene equivalents well above the equilibrium concentration observed in abiotic controls. This mobilization was attributed to biosorption and cometabolism processes occurring in parallel. HPLC quantification revealed pyrene concentrations well below the 14C-based quantifications by liquid scintillation, indicating pyrene transformation into water-soluble polar metabolites. The results from transport experiments in sand columns revealed that cometabolic-active, motile cells were capable of accessing a distant source of sorbed pyrene. Using the same experimental system, we also determined that salicylate-mobilized cells, inhibited for pyrene cometabolism, but mobilized due to their tactic behavior, were able to sorb the compound and mobilize it by biosorption. Our results indicate that motile bacteria active in bioremediation may contribute, through cometabolism and biosorption, to the risk associated to pollutant mobilization in soils. This research could be the starting point for the development of more efficient, low-risk bioremediation strategies of poorly bioavailable contaminants in soils. © 2020 Elsevier B.V., We thank the Spanish Ministry of Economy, Industry and Competitiveness (CGL2016-77497-R), the Andalusian Government (RNM 2337), and the European Commission (LIFE15 ENV/IT/000396). Joaquim Vila is a Serra Húnter Fellow (Generalitat de Catalunya).

Fagus sylvatica L. is widely distributed across Europe thanks to its high adaptability in a wide variety of soils and climate. Microbial communities are essential for maintaining forest soil quality and are responsible for forest ecosystem functioning; the ability of soil microorganisms to respond to abiotic stressors (e.g., organic carbon losses, water scarcity, temperature changes) is crucial under ongoing environmental changes and also supports tree health. In this study, soil samples were collected from pure beech plots as part of the COST Action project CLIMO to find differences in microbial community characteristics and evaluate the effects of soil properties on microbial communities across gradients of elevation, latitude, and longitude. Positive relationships were found between organic carbon content and both microbial abundance and dehydrogenase activity. Dehydrogenase and catalase activities were elevation-correlated and microbial activities were longitude-correlated. In the most southern beech plot, the microbial community was abundant and displayed high activities. This shows that microbial communities could help tree populations to better adapt to predicted changes in environmental conditions in the future. We suggest that research into forest health and beech performance should also test soil microbial enzymatic activity, particularly under changing climate conditions, to assist in identifying adaptation strategies.

Water pollution by heavy metals is a matter of growing concern due to their potential toxicity for biota. The development of new and cost-effective remediation strategies is a priority in this field. For this purpose, a green technology, consisting of organic waste made up of a composite of water hyacinth dry matter and sodium alginate in microsphere form, was tested for its potential to adsorb lead and cadmium in river water samples. The water hyacinth‑sodium alginate composite molecular conformation was analysed first in order to obtain the potential energy surfaces. A high dipole moment, useful for the adsorption of heavy metals, was found. Accordingly, the cross-linked microspheres were prepared by combining water hyacinth dry matter and sodium alginate in a 1:1 ratio. Their metal adsorption and any effect on the natural microbial river community were verified with laboratory microcosm experiments lasting 11 days, using river water spiked with lead and cadmium (1 mg/L each). For this purpose, chemical (metal concentrations) and microbial (microbial abundance, viability and taxonomic composition) analyses were performed. Moreover, the ecotoxicity (with Vibrio fischeri - ISO 11348-3:2007) of water samples from microcosms in the presence/absence of the microspheres and metals was assessed. Effective concentrations (EC20 and EC50) of Pb and Cd were also determined. Finally, electron microscopy analyses were performed with a Field Emission Scanning Electron Microscope (FE-SEM) to visualize the metal adsorption capacity of the microspheres and investigate the metal distribution on the spheres (adsorbed on the surface or inside). The overall results showed that the microspheres were able to remove high heavy metal concentrations (about 1 mg/L) from river water in a short time (at 96 h just 1.3% and 5.8% of the Pb and Cd initial concentrations were detected) and no ecotoxicological effects were recorded. Moreover, the microspheres had a positive effect on the microbial community by promoting an increase in live cell numbers, probably through the release of organic carbon. Further analyses (at about four months) showed that the microspheres were able to keep metals adsorbed for a long time. These results show that the green technology proposed is an effective remediation method for Pb and Cd removal from river water and is very promising, not least because of its low cost.

River pollution from different sources can affect ecosystems in different ways with consequences on water quality for both biota and human health. The River Danube was selected to perform chemical and biological analyses. The river was sampled at three different points, one inside Budapest and two just outside. Water samples were collected twice in the same year (April and November 2017) in order to determine metal concentrations, occurrence of ubiquitous contaminants such as Polycyclic Aromatic Hydrocarbons (PAHs) and some not-yet-regulated pharmaceuticals (17β-estradiol, 17α-ethinylestradiol, estrone, fenoprofen, naproxen, ibuprofen, gemfibrozil, sulfamethoxazole and ciprofloxacin). Moreover, the structure of the natural microbial community was also analysed in terms of total microbial abundance and identification of the main bacterial groups by the Fluorescence In Situ method. Finally, the same water samples were tested to assess their possible estrogenic effects using the yeast estrogenic screen (YES). The results show diffuse residual concentrations of both PAHs and pharmaceuticals in the river stretch investigated, with the highest values in April (in line with a lower rainfall input) and at the sampling site inside the city of Budapest. At this latter point, the natural microbial community was less abundant than in the other sites, suggesting detrimental effects of the overall contaminants on its structure. Finally, an estrogenic activity was found in all water samples analysed with higher average values in line with higher amounts of contaminants in the April sampling.

The anionic surfactant sodium lauryl ether sulphate (SLES) is the main component in most foaming agents used for mechanized tunneling excavation. The process produces huge amounts of soil debris that can have a potential impact on ecosystems. The lack of accurate information about SLES persistence in excavated soil has aroused increasing concern about how it is recycled. The objective of this study was to assess SLES biodegradability in two commercial foaming agents (P1 and P2). Microcosm experiments were performed with two different soils collected from a tunnel construction site and conditioned with P1 or P2 (85.0 or 83.0 mg kg −1 of SLES, respectively). At selected times soil samples were collected for assessing the SLES residual concentration using Pressured Liquid Extraction followed by methylene blue active substance analysis (MBAS). Simultaneously, soil microbial abundance (DAPI counts), viability (Live/Dead method), activity (dehydrogenase analysis) and phylogenetic structure (Fluorescent In Situ Hybridization) were evaluated. SLES halved faster in the silty-clay soil (6 d) than in the gravel in a clay-silty-sand matrix (8–9 days). At day 28 it was degraded in both soils. Its biodegradation was ascribed to the significant increase in Gamma-Proteobacteria. At this time, the spoil material can be considered as a by-product.

The rhizosphere is a microhabitat where there is an intense chemical dialogue between plants and microorganisms. The two coexist and develop synergistic actions, which can promote plants’ functions and productivity, but also their capacity to respond to stress conditions, including heavy metal (HM) contamination. If HMs are present in soils used for agriculture, there is a risk of metal uptake by edible plants with subsequent bioaccumulation in humans and animals and detrimental consequences for their health. Plant productivity can also be negatively affected. Many bacteria have defensive mechanisms for resisting heavy metals and, through various complex processes, can improve plant response to HM stress. Bacteria-plant synergic interactions in the rhizosphere, as a homeostatic ecosystem response to HM disturbance, are common in soil. However, this is hard to achieve in agroecosystems managed with traditional practices, because concentrating on maximizing crop yield does not make it possible to establish rhizosphere interactions. Improving knowledge of the complex interactions mediated by plant exudates and secondary metabolites can lead to nature-based solutions for plant health in HM contaminated soils. This paper reports the main ecotoxicological effects of HMs and the various compounds (including several secondary metabolites) produced by plant-microorganism holobionts for removing, immobilizing and containing toxic elements.

Some livestock farms rely on anaerobic digestion (AD) technology for manure disposal, thus obtaining energy (biogas) and fertilizer (digestate). Mixtures of antibiotics used for animal health often occur in organic waste and their possible synergistic/antagonistic effects on microorganisms involved in AD are still poorly studied. This work focuses on the effects of adding ciprofloxacin, alone (5 mg L−1) and in combination with sulfamethoxazole (2.5–5–10 mg L−1), on AD efficiency and microbial community structure. The experiment consisted of 90-day cattle manure batch tests and antibiotic removal percentages were assessed. Adding antibiotics always promoted CH4 and H2 production compared to untreated controls; however, CH4 production was lowered with the highest ciprofloxacin (CIP) concentrations. The overall results show antibiotic degradation caused by acidogenic Bacteria, and CH4 was mainly produced through the hydrogenotrophic-pathway by methanogenic Archaea. Shifts in microbial community abundance (DAPI counts) and composition (Illumina-MiSeq and FISH analyses) were observed.

The anionic surfactant Sodium Lauryl Ether Sulfate (SLES) is the principal component of several commercial foaming products for soil conditioning in the tunneling industry. Huge amounts of spoil material are produced during the excavation process and the presence of SLES can affect its re-use as a by-product. Anionic surfactants can be a risk for ecosystems if occurring in the environment at toxic concentrations. SLES biodegradability is a key issue if the excavated soil is to be reused. The aim of this study was to identify bacteria able to degrade SLES, so that it could potentially be used in bioaugmentation techniques. Enrichment cultures were performed using bacterial populations from spoil material collected in a tunnel construction site as the inoculum. A bacterial consortium able to grow in a few hours with SLES concentrations from 125 mg/L to 2 g/L was selected and then identified by Next Generation Sequencing analysis. Most of bacteria identified belonged to Gamma-Proteobacteria (99%) and Pseudomonas (ca 90%) was the predominant genus. The bacterial consortium was able to degrade 94% of an initial SLES concentration of 250 mg/L in 9 h. A predictive functional analysis using the PICRUSt2 software showed the presence of esterase enzymes, responsible for SLES degradation. The bacterial consortium selected could be useful for its possible seeding (bioaugmentation) on spoil material from tunneling excavation.

Background: Due to their widespread use in industrial applications in recent decades, Polychlorobiphenyls (PCBs) and heavy metals (HMs) are the most common soil contaminants worldwide, posing a risk for both ecosystems and human health.Results: a poplar-assisted bioremediation strategy has been applied for more than four years to a historically contaminated area (PCBs and HMs) in Southern Italy using the Monviso poplar clone. This clone was effective in promoting a decrease in all contaminants and an increase in soil quality in terms of organic carbon and microbial abundance. Moreover, a significant shift in the structure and functioning of the belowground microbial community was also observed when analysing both DNA and cDNA sequencing. In fact, an increase in bacterial genera belonging to Proteobacteria and able to degrade PCBs and resist HMs was observed. Moreover, the functional profiling of the microbial community predicted by PICRUSt2 made it possible to identify several genes associated with PCB transformation (e.g. bphAa, bphAb, bphB, bphC), response to HM oxidative stress (e.g. catalase, superoxide reductase, peroxidase) and HM uptake and expulsion (e.g. ABC transporters).Conclusions: This work demonstrated the effectiveness of the poplar clone used in stimulating the natural belowground microbial community to remove contaminants (phyto-assisted bioremediation) and improve the overall soil quality. It is a practical example of a nature based solution involving synergic interactions between plants and the belowground microbial community.

Sodium lauryl ether sulphate (SLES) is the main chemical component in several lubricant products used for soil conditioning in the mechanized excavation industry using Earth Pressure Balance-Tunnel Boring Machines. During the tunnelling process, huge amounts of excavated soil are produced and the SLES presence can affect the subsequent re-use of this material as a by-product. Currently, there is still no regulatory indication of reliable and sensitive bioassays for monitoring soil quality during the excavation process. The main objective of this work was to verify if the Vibrio fischeri screening test was suitable as a consistent and precautionary tool for this specific purpose. Firstly, the ecotoxicity (EC20 and EC50) of the SLES standard solution and three commercial products (SLES content from 10 to 50%) were evaluated to select the most environmental friendly product. Subsequently, soil samples from about 2 years of tunnelling in a real construction site, conditioned with the selected product, were evaluated for their environmental compatibility with the prescriptions of an Italian site-specific protocol. The latter established 2 mg/L as a threshold value for SLES concentration in soil water extracts and a no toxic response (2 mg/L. The toxicity was directly related to SLES concentration, indicating that the V. fischeri test and the SLES analyses are suitable tools for assessing excavated soil as a by-product, ensuring its safe reuse in accordance with a green production process (circular economy).

In recent decades, the innovative practice of management and valorization of agrozootechnical waste as energy through anaerobic digestion (AD) has been rapidly growing. However, whether applying digestate to soil as biofertilizer can be a source of antibiotics (ABs) and antibiotic resistance genes (ARGs) has not been fully investigated so far. In this work the ARGs responsible for sulfamethoxazole (SMX) resistance (sul1, sul2), ciprofloxacin (CIP) resistance (qnrS, qepA, aac-(6′)-Ib-cr) and the mobile genetic element intl1, together with the concentrations of the antibiotics SMX and CIP, were measured in several anaerobic digesters located in Central Italy. Based on these results, the concentrations of antibiotics and ARGs which can potentially reach soil through amendment with digestate were also estimated. The highest CIP and SMX concentrations were found during winter and spring in anaerobic digesters. The highest ARG abundances were found for the aac-(6’)-Ib-cr and sul2 genes. The overall results showed that application of digestate to soil does not exclude AB contamination and spread of ARGs in agroecosystems, especially in the case of ciprofloxacin, owing to its high intrinsic persistence.

Mechanized excavation of tunnels with Earth Pressure Balance-Tunnel Boring Machines requires the use of foaming agents. The latter contain the anionic surfactant sodium lauryl ether sulphate (SLES) as the main compound. The re-use as a by-product of excavated soil containing foaming agents (spoil material) can pose a risk for soil and particularly for aquatic ecosystems if they are close to the spoil material final destination site. This work reports the chemical results (SLES residual concentrations) and ecotoxicological effects (battery of five tests) of 28 day-mesocosm studies performed at a tunnelling construction site. The soil mesocosms were set up with two different lithologies, which contained four different foaming agent products at the highest amounts used for excavation. The decrease in SLES concentrations and the ecotoxicological tests were performed in soil and its water extract (elutriate) at different times (0, 7, 14, 28 d). Elutriates were prepared in order to simulate a possible SLES leaching from soil to water. The results showed a decrease in SLES over time and different ecotoxicological responses depending not only on the initial amount of each product, but also on the soil lithology and organism tested (aquatic or terrestrial). This study showed how only site-specific ecotoxicological evaluations can ensure a safe management of the spoil material, making possible the re-use of soil and avoiding production of waste.

Alkylethoxysulfate (AES) surfactants are the main component of most commercial products used for soil conditioning in the excavation industry, in particular as lubricants for mechanized tunnelling. Huge amounts of soil debris are produced during the excavation process and their possible re-use as by-products (e.g. land covering) or discharge as waste is a critical question in civil engineering. There can be an environmental impact from the potential ecotoxicity of the residual chemical mixture occurring in the foam-conditioned excavated soil. Chemical analyses are not able on their own to assess the potential hazards for the ecosystem ascribable to inadequate management of this kind of conditioned soil. Ecotoxicological tests, on the other hand, provide useful overall information about the potential effects of conditioned debris on soil and aquatic biota, including synergic ones, whether or not there is a detailed knowledge of the chemical composition of all the components of the commercial foaming products. In this context, the objective of this work was to evaluate the overall ecotoxicity of excavated soil conditioned with two common foaming products containing sodium lauryl ether sulphate (SLES) as the main component, in order to verify their possible re-use as by-products. For this purpose, two soils with different geopedological characteristics were conditioned with the commercial foaming agents at the concentrations utilised for mechanized tunnelling and then used for microcosm laboratory experiments. Soil sub-samples were collected at different times (0, 7, 14, 28 days) of incubation and soil elutriates were produced to assess the effects of the foaming agents on five test species (Pseudokirchneriella subcapitata, Daphnia magna, Danio rerio, Vibrio fischeri and Lepidium sativum). The results of the tests were then compared with SLES residual concentrations in the elutriates, determined with the MBAS (methylene blue active substances) spectrophotometric method. Finally, the data were combined in a battery index, which proved effective at evaluating the overall ecotoxicity in a real-life situation of two different excavated soils conditioned with the two products analysed.

Among the different pharmaceuticals present in soil and water ecosystems as micro-contaminants, considerable attention has been paid to antibiotics, since their increasing use and the consequent development of multi-resistant bacteria pose serious risks to human and veterinary health. Moreover, once they have entered the environment, antibiotics can affect natural microbial communities. The latter play a key role in fundamental ecological processes, most importantly the maintenance of soil and water quality. In fact, they are involved in biogeochemical cycling and organic contaminant degradation thanks to their large reservoir of genetic diversity and metabolic capability. When antibiotics occur in the environment, they can hamper microbial community structure and functioning in different ways and have both direct (short-term) and indirect (long-term) effects on microbial communities. The short-term ones are bactericide and bacteriostatic actions with a consequent disappearance of some microbial populations and their ecological functioning. The indirect impact includes the development of antibiotic resistant bacteria and in some cases bacterial strains able to degrade them by metabolic or co-metabolic processes. Biodegradation makes it possible to completely remove a toxic compound from the environment if it is mineralized. Several factors can influence the significance of such direct and indirect effects, including the antibiotic's concentration, the exposure time, the receiving ecosystem (e.g. soil or water) and the co-occurrence of other antibiotics and/or other contaminants. This review describes the current state of knowledge regarding the effects of antibiotics on natural microbial communities in soil and water ecosystems.

The widespread detection of antibiotics in terrestrial and aquatic systems has engendered significant scientific and regulatory concern. Overall, knowledge concerning the ecotoxicology and sub-lethal effects in water is scarce, but some experimental studies show that antibiotics can induce pathogen resistance and they can also have detrimental effects on natural microbial communities and their key functions. The main aim of this study was to investigate the occurrence of the biodegradation and photodegradation processes of the fluoroquinolone ciprofloxacin (CIP) in the River Tiber waters, in a stretch highly impacted from human pressure. Two set of microcosms consisting of river water containing the natural microbial community and treated with 500 μg/L of CIP in absence or presence of UV-light were performed. Moreover, some microcosms were filled with river water previously sterilized and then treated with the antibiotic. The combined experimental set made it possible to evaluate if the antibiotic CIP could be photodegraded and/or biodegraded. CIP residual concentrations were measured over time by using HPLC coupled to fluorescence detection (FLD) and the effects of the antibiotic on the natural microbial community were assessed in terms of live cell abundance. The key role of light in CIP disappearance was confirmed, but also its biodegradation in natural river water was demonstrated. In fact, differently from other experiments we found a higher degradation rate (DT 50 = 10.4 d), in presence of both light and the natural river bacterial populations than in the same sterilized river water (DT 50 = 18.4 d). Moreover, even in the dark, a partial CIP biodegradation was also observed (DT 50 = 177 d). The overall results were supported by the increase in live cell numbers with the decrease of CIP concentrations both in the dark and light condition.

Gemfibrozil is a pharmaceutical commonly found in the aquatic compartment and its presence together with a mixture of several other biologically-active drugs raises concern about the possible long-term adverse effects on biota chronically exposed. Most research focus on its effect/degradation in wastewater treatment plant, while few investigations take into account its persistence in receiving aquatic ecosystems and its effects on natural microbial communities. In this context, the present work aims to evaluate gemfibrozil biodegradation, alone or in the co-presence of naproxen, comparing its persistence in the presence/absence of the river natural microbial community. For this purpose, water samples were collected from a river Tiber stretch inside the city of Rome and located downstream from a wastewater treatment plant and used for degradation experiments. Microbiologically active or sterile water microcosms were set up and treated with 100 μg L− 1 of gemfibrozil alone or in the co-presence of naproxen (100 μg L− 1), in order to evaluate gemfibrozil degradation in the different conditions. At fixed times water samplings were collected for both chemical and microbiological analysis. Moreover, the effects of the pharmaceuticals on the microbial community structure in terms of variations in its abundance and composition were also assessed. The overall results showed gemfibrozil to be a quite persistent molecule in the river water microcosms and the natural microbial community had a key role in its biodegradation. The co-presence of naproxen, a non-steroidal anti-inflammatory drug commonly co-occurring with gemfibrozil, increased its persistence and affected negatively some bacterial groups presence.

Leaf transpiration drives many of the processes involved in phyto-technologies, and it can represent a useful mechanism to remove water from different kind of storage basins presenting inorganic, organic or microbiological contamination (phyto-dehydration), with the aim to reduce the risk of environmental contamination. In this framework, a mesocosm-scale trial was carried out to test the capacity of different helophyte species to reduce the excess of water in an artificial pond filled with oversaturated sludge. The sludge derives from the digestion of pig slurries, presents high levels of zinc and copper and for most of the year is covered by a water layer of about 20 cm due to rainfalls. This layout (water layer over the sludge) was reproduced inside the mesocosms, where four helophyte species (Phragmites australis and a mix of Carex acutiformis, Iris pseudacorus and Juncus effusus) were planted on floating frames. Plant growth and functionality were monitored for one year, along with their water consumption capacity; the vegetation impact on sludge chemistry, sludge microbial community and sludge greenhouse gases emission/uptake were also evaluated. The sensitivity of the phyto-dehydration system to the reduction of water level occurring during summer in the pond was investigated reducing the water input to the mesocosms. P. australis and C. acutiformis successfully established in the mesocosms, while a significant mortality was recorded for I. psudacorus and J. effusus. Once established, plants were able to grow in the mesocosms, and no metal toxicity effect was observed on photosynthesis rates that were comparable with values reported for natural stands of the species. Plants significantly increased (from 24 to 63%, depending on the species) the amount of water lost by the mesocosms and counteracted the reduction of sludge organic carbon that could lead to a mobilization of the heavy metals bound to organic matter: furthermore, plants decreased the rates of mesocosm greenhouse gas emission and reduced the sludge pathogen (Enterobacteriaceae) occurrence. Water limitations reversibly reduced the water consumption and CO2 uptake capacity of the mesocosms. The results of this study demonstrated that the water balance of a sludge/water system can be effectively modified through the phyto-dehydration approach, increasing significantly the amount of water lost. Although the low tolerance of two species to the sludge/water environment after plantation needs to be further investigated, this phyto-technology can represent a promising approach to manage the excess of water in polluted ponds.

The anionic surfactant sodium lauryl ether sulphate (SLES) is the main component of most commercial products used for soil conditioning in the excavation industry, in particular as lubricants for mechanized tunnelling. Its use during the excavation processes can result in either the subsequent possible re-use of the huge amount of soil debris as by-products (e.g. land covering) or its discharge as waste. Currently, there are neither SLES soil threshold limits in European legislation, nor comprehensive studies on the environmental risk for soil ecosystems in these exposure scenarios. In this context, the present paper reviews the available data on the intrinsic characteristics of persistence and the ecotoxicological effects of the anionic surfactant SLES. Although SLES is generally reported to be biodegradable in standard tests, with degradation rates between 7 h and 30 days, depending on the initial conditions, data on its biodegradation in environmental studies are quite scarce. Consequently, assessing SLES biodegradation rates in field conditions is crucial for evaluating if in residual concentrations (typically in the range 40–500 mg/kg in excavated soils) it can or not be a potential hazard for terrestrial and water organisms. Laboratory ecotoxicological tests pointed out detrimental effects of SLES for aquatic organisms, while data on the terrestrial species are rather poor so far and further studies at the expected environmental concentrations are necessary. Finally, the review reports the main analytical methods available for detecting anionic surfactants in solid matrices and the future research needed to improve knowledge on the possible environmental risks posed by the use of SLES in foaming agents for mechanized tunnelling.

Due to their widespread use in industrial applications in recent decades, Polychlorobiphenyls (PCBs) and heavy metals (HMs) are the most common soil contaminants worldwide, posing a risk for both ecosystems and human health. In this study, a poplar-assisted bioremediation strategy has been applied for more than 4 years to a historically contaminated area (PCBs and HMs) in Southern Italy using the Monviso poplar clone. This clone was effective in promoting a decrease in all contaminants and an increase in soil quality in terms of organic carbon and microbial abundance. Moreover, a significant shift in the structure and predicted function of the belowground microbial community was also observed when analyzing both DNA and cDNA sequencing data. In fact, an increase in bacterial genera belonging to Proteobacteria able to degrade PCBs and resist HMs was observed. Moreover, the functional profiling of the microbial community predicted by PICRUSt2 made it possible to identify several genes associated with PCB transformation (e.g., bphAa, bphAb, bphB, bphC), response to HM oxidative stress (e.g., catalase, superoxide reductase, peroxidase) and HM uptake and expulsion (e.g., ABC transporters). This work demonstrated the effectiveness of the poplar clone Monviso in stimulating the natural belowground microbial community to remove contaminants and improve the overall soil quality. It is a practical example of a nature based solution involving synergic interactions between plants and the belowground microbial community., This research was performed for the Project “GREEN SOLUTIONS – Biorimedio fitoassistito: una strategia verde per il recupero di aree contaminate e la valorizzazione di biomassa” http://www.soluzioniverdi.eu/wordpress funded by Apulia Region (Italy) in the framework of INNONETWORK – POR PUGLIA FESR-FSE 2014-2020, N. Q3ITQH5. We declare that Apulia Region did not have any role in the design of the study, sample collection, analysis, interpretation of data, and in writing the manuscript.

BACKGROUND: The Monviso clone previously tested successfully to remediate a lindane‐contaminated soil in central Italy was then applied in a historically heavy metal contaminated area in southern Italy. RESULTS: The results obtained at 900 days from the poplar planting showed a strong decrease below Italian national legal limits (D.Lgs 152/06) for most heavy metals (HMs). The highest reduction of HM concentrations was observed in soil samples collected near the trunk (25 cm distant from poplar) and in the rhizosphere. The values of the HM bioaccumulation factor (BAF, considering roots and leaves) and of the translocation factor (TF) suggest that poplar trees were able to phytostabilize HMs. The soil organic carbon content increased compared to the previous sampling in all plots planted. The highest values were observed for the rhizosphere soils of each target tree, while the phosphorous available strongly decreased. Microbial results showed an overall increase in cell viability, dehydrogenase activity and microbial abundance of some bacterial groups. CONCLUSION: Overall results showed that the poplar‐based phytoremediation strategy was able to promote the phytostabilization of the HMs and to improve the soil quality in terms of both organic carbon content and microbial community structure and activity. © 2019 Society of Chemical Industry

Most of the Earth’s surface (71%) is covered with water, and the oceans hold about 96 [...]

Remediation of polluted soils using phytoremediation techniques is an effective strategy. However, the use of the biomass from these soils for energy purposes may raise efficiency and pollution emission problems and there is currently little research on this issue. In this work, the main results of a fluidized-bed gasification treatment conducted on poplar biomass pruning residues from a multi-contaminated area are presented. The samples were collected from an experimental site in which a plant-assisted bioremediation (PABR) technology has been applied since 2013 to reduce the soil heavy metal (HM) and polychlorinated biphenyl (PCB) contents. The main goal of this study was to identify the specific treatment necessary, in addition to conventional tar reforming, for trapping possible residues of HMs and PCBs in ashes during the gasification process. In our study, we demonstrate that gasification of contaminated biomass coming from PABR (where contaminant residues are concentrated mainly in the roots and are insignificant in the shoots) produces syngas whose characteristics are similar to those obtained using non-contaminated biomass. The results showed that contaminant concentrations in the prunings were negligible; the total amount of PCBs was 1.63 ng/g, while HMs ranged from 0.01 to 0.70 mg/kg, except for Cu and Zn (∼20 mg/kg). Furthermore, the presence in the biomass of Ca and traces of other metals showed a possible catalytic effect with an improvement in the tar conversion in the gasifier leading to a reduction of 5–10% in tar content. The overall results suggest that a specific treatment for pollutant capture is necessary only when the roots, the part of the plants where these contaminants are concentrated, are sampled and used for the gasification process. Although energy from biomass produced on a contaminated site is currently considered waste and involves disposal costs, this paper shows that the poplar biomass grown on a multi-contaminated soil can be used for energy purposes without any impact on the environment.

Sulfamethoxazole and ciprofloxacin are among the most prescribed antibiotics and are frequently detected in surface water ecosystems. The aim of this study was to assess the role of a riverine natural microbial community in sulfamethoxazole (SMX) degradation in presence and absence of ciprofloxacin (CIP). River samples were collected from a stretch of the Tiber River highly impacted by human pressure. An experimental set up was performed varying some abiotic (dark/UV-light) and biotic (presence/absence of microorganisms) conditions that can affect antibiotic degradation. The residual concentrations of SMX and CIP were measured (HPLC-MS or HPLC-UV/FLD) and the effects on the natural microbial community were assessed in terms of microbial number (N. live cells/mL) and structure (Fluorescence In Situ Hybridization - FISH). Finally, the occurrence of the antibiotic resistance sul1 gene was also verified using quantitative PCR (qPCR). In 28 days, in the presence of both UV-light and microorganisms SMX disappeared (

We studied the changes in structure and functioning of the microbial community in a degraded agricultural soil after the addition of two composts, obtained from cattle manure or pig slurry anaerobic digestate, and the use of rosemary plants for restoring soil quality. The composts were added at low or high doses to soil samples (30 or 60 t ha − 1 , respectively), which were kept in microcosms for 6 months. Some soil microcosms were treated with inorganic fertiliser and other non-treated soils were used as microbiological controls. Rosemary plants, used both for their ability to grow in semi-arid regions and for the capacity of their root system to protect soil from erosion, were planted in half of the entire microcosm set up. At different times (0–180 days) microbial abundance and dehydrogenase activity were measured in the various experimental treatments. Total and water-soluble soil organic carbon and nitrogen contents were assessed at 0 and 180 days. With an increase in carbon and nitrogen soil content, a rise in microbial abundance was also observed in the presence of both composts. However, microbial activity was significantly influenced by the presence of rosemary, without considering the allochthonous carbon and nitrogen input. Microbial community structure and diversity were also assessed by Fluorescence In Situ Hybridization in the different treatments. The highest values for microbial community biodiversity were found in the co-presence of rosemary and at low concentrations of both composts. The overall results suggest that the use of composts together with plant species suited to Mediterranean areas seems to be an appropriate strategy for restoring soil quality and the ecosystem services provided by microorganisms.

Trees are crucial for sustaining life on our planet. Forests and land devoted to tree crops do not only supply essential edible products to humans and animals, but also additional goods such as paper or wood. They also prevent soil erosion, support microbial, animal, and plant biodiversity, play key roles in nutrient and water cycling processes, and mitigate the effects of climate change acting as carbon dioxide sinks. Hence, the health of forests and tree cropping systems is of particular significance. In particular, soil/rhizosphere/root-associated microbial communities (known as microbiota) are decisive to sustain the fitness, development, and productivity of trees. These benefits rely on processes aiming to enhance nutrient assimilation efficiency (plant growth promotion) and/or to protect against a number of (a)biotic constraints. Moreover, specific members of the microbial communities associated with perennial tree crops interact with soil invertebrate food webs, underpinning many density regulation mechanisms. This review discusses belowground microbiota interactions influencing the growth of tree crops. The study of tree-(micro)organism interactions taking place at the belowground level is crucial to understand how they contribute to processes like carbon sequestration, regulation of ecosystem functioning, and nutrient cycling. A comprehensive understanding of the relationship between roots and their associate microbiota can also facilitate the design of novel sustainable approaches for the benefit of these relevant agro-ecosystems. Here, we summarize the methodological approaches to unravel the composition and function of belowground microbiota, the factors influencing their interaction with tree crops, their benefits and harms, with a focus on representative examples of Biological Control Agents (BCA) used against relevant biotic constraints of tree crops. Finally, we add some concluding remarks and suggest future perspectives concerning the microbiota-assisted management strategies to sustain tree crops.

Sulfamethoxazole (SMX) is a sulfonamide antibiotic commonly used in human and veterinary medicine and frequently detected in surface water as a micro-contaminant. The presence of this antibiotic and its main transformation product N4-acetyl-sulfamethoxazole (Ac-SMX) was evaluated in an Italian river water by Solid Phase Extraction (SPE) and subsequent LC MS/MS determination. River water microcosm experiments were set up in the presence and absence of duckweed (Lemna minor L.) adding SMX (500 μg L−1) with the aim of evaluating the persistence of antibiotic and its effects on both the microbial community naturally occurred in a river and the plant. The concentrations of SMX and Ac-SMX were measured at fixed times over a period of 28 days. The microbial abundance, intI1 gene and plant morpho-physiological analyses were also conducted. In the river water samples, SMX was not detected as a parent compound, but its acetylate metabolite Ac-SMX was found as a micro-contaminant. The results of the microcosm experiment showed that SMX did not substantially degrade, except in the presence of L. minor where a slight decrease (17%) was observed. The river residual concentration of Ac-SMX remained quite constant during the experimental period. The river microbial community was initially affected by adding the antibiotic with a decrease in its abundance; however, although it was not able to degrade SMX, it displayed an overall antibiotic resistance. In fact, the intI1 gene was found throughout the entire experimental period. Finally, SMX did not cause evident inhibition or suffering symptoms for the plant.

The presence of pharmaceutical active products (PPs) in the aquatic environment is principally due to insufficient removal at wastewater treatment plants (WWTPs). Although PPs and their metabolites are often found in waters at trace levels, they can maintain a high biological activity with potential adverse effects on biotic communities. The development of accurate and sensitive methods is therefore necessary for their detection in aquatic ecosystems. In this context, the aim of this study was to validate a simple and reliable analytical procedure for determining selected pharmaceuticals in wastewaters and surface waters by applying solid phase extraction (SPE) using polymeric Strata X extraction cartridges and HPLC with simultaneous UV and fluorescence detection. Nine selected PPs belonging to different therapeutic classes (carbamazepine, gemfibrozil, clofibric acid, fenofibrate, fenoprofen, ibuprofen, naproxen, ketoprofen, and diclofenac) and three steroid hormones (17β-estradiol, 17α-ethinylestradiol, and estrone) were considered. The method, validated on spiked real water samples (river water, influent and effluent from a WWTP), showed satisfactory accuracy and sensitivity, with average recoveries in the 65–104% range and relative standard deviations (RSD) ≤ 16%. The limits of quantification (LOQs) ranged from 10 to 1100 ng/L for all spiked matrices. The optimized method has been successfully applied to the detection of the selected compounds in environmental waters, such as two contaminated sites along the urban stretch of the River Tiber in the city of Rome (Italy) and from both the influent and effluent from a municipal WWTP close to Rome. The method developed is proposed for routine analysis of PPs in polluted waters as it is a useful and affordable alternative when more sophisticated techniques are not available.

Soil and water microorganisms play an important role in maintaining ecosystem environmental quality. In fact, the ability of soil and water to recover from chemical contamination is primarily dependent on the presence of a microbial community with the ability to remove it. In this way, the microbial community represents an important key to understanding the impacts of environmental and anthropogenic factors on ecosystems. The presence of an abundant and varied microbial community is a necessary prerequisite for an immediate and effective response to the various natural and anthropic disturbances that can affect an ecosystem. Soil and water microcosm studies enable the studying, under controlled conditions, of the effects of selective pressures, such as xenobiotic occurrence on natural microbial communities. In this paper the main data (in terms of chemical persistence and bacterial abundance) of several microcosm degradation studies performed using natural soil and water were collected and discussed. The biotic and abiotic degradation of several contaminants (including the parent compounds of pesticides and pharmaceuticals and their metabolites) was evaluated comparing microbiologically active microcosms treated with the chemical with others previously sterilized. Moreover, in some cases additional microcosms were also used for evaluating the effect of some amendments (such as urea or wood amendments) on microbial degradation. The disappearance time of 50% of the compound applied (DT 50 ) was evaluated for each chemical in the presence/absence of the natural microbial community in 19 microcosm experiments, performed using 16 different chemicals considered environmental contaminants. The overall results presented here show the key role of microorganisms in the degradation of all the chemicals studied and establish the relationship between degradation and the role of microbial communities in chemical disappearance from the environment, thus demonstrating the suitability of the of the microcosm approach for reproducing more realistic environmental exposure scenarios in the laboratory.

Ecosystem services are the contributions that ecosystems provide to human well-being. They arise from the interaction of biotic and abiotic processes, and refer specifically to the ‘final’ outputs or products from ecological systems. Soil harbours a large proportion of Earth's biodiversity, and provides the physical substrate for most human activities. Although soils have been widely studied and classified in terms of physical and chemical characteristics, knowledge of soil biodiversity and functioning are still incomplete. Soil organisms are extremely diverse and contribute to a wide range of ecosystem services that are essential to the sustainable functioning of natural and managed ecosystems. Microbial communities (mainly composed by Bacteria, Archaea and microfungi) are vital to soil ecosystem functioning. This is because they exist in enormous numbers and have an immense cumulative mass and activity. Most of the phenomena observed in the visible aboveground world are steered directly or indirectly by species, interactions, or processes in the belowground soil. In particular, being microbial communities involved in nutrient cycling and organic matter degradation, they can affect biodiversity and productivity of aboveground ecosystems. Microorganisms can have stimulating or inhibiting effects on plants by the release of metabolites with a varying range of activities. Microbial communities are the main responsible of soil homeostatic capabilities removing contaminants and providing key ecosystem regulating and supporting services such as soil fertility, resilience and resistance to different stress. This chapter aims at describing the contributions provided by soil microbial communities to different ecosystem services and their potential use as indicators of ecosystem functioning. Understanding ecosystem functioning and predicting responses to global changes calls for much better knowledge than we have today about microbial processes and interactions, including those with plants in the rhizosphere.

Plant-based clean up technologies are gaining popularity as a sustainable solution to contaminated soil remediation. In particular, plant-assisted bioremediation or phyto-assisted bioremediation exploits the synergistic action between plant root systems and natural microorganisms (bacteria and fungi) to remove, convert or contain toxic substances in soils, sediments or water. It can be applied successfully to contaminated areas. It relies on the use of a selected appropriate plant species for stimulating the biodegradation activity of natural soil microorganisms in the rhizosphere (e.g. through root exudates production or oxygen transport). Plant species can also produce extracellular enzymes that directly transform contaminants and/or make them more bioavailable. Moreover, they can also phyto-contain them. In selecting the plant species, the specific contaminant/s to be removed, and the local geopedological and climatic conditions need to be considered. Beyond the contaminant removal, there are additional benefits such as soil quality improvement, soil carbon sequestration and biomass production for energy purposes. The difficulties in remediating areas characterized by multiple pollutant occurrence (e.g. organic and inorganic toxic compounds) make the study of plant-microbial interactions important if sustainable soil recovery strategies are to be achieved. Consequently, in recent years, several plant species have been tested for stimulating natural microbial communities and supporting the remediation of contaminated soils. Among these, the poplar tree can be considered suitable for plant-assisted bioremediation purposes. In this chapter an example of the methodological approach used for its application to an area multi-contaminated (by polychlorinated biphenyls and heavy metals) is illustrated.

Our knowledge of microbial soil biodiversity depends on the ability to combine different observation levels, ranging from the phenotypic to the molecular one, including direct visualization of microorganisms by using an epifluorescence microscope. Soil microbial communities, although still largely undiscovered, represent one of the biggest part of present biodiversity and play a key role in all soil processes. For example, microbial abundance, activity and composition largely determine the sustainable productivity of agricultural land or the degradation of organic pollutants. The diversity of microbial communities associated with plant roots is enormous, in the order of thousands of species. The simultaneous use of different molecular methods makes it possible to have a more holistic knowledge of the soil microbial community and to assess changes in it under different conditions. In this chapter we report the application to the same soil samples of two different phylogenetic molecular techniques, i.e. DGGE (Denaturing Gradient Gel Electrophoresis) and FISH (Fluorescence In Situ Hybridization). DGGE is a useful fingerprint technique of the overall microbial community based on amplification of 16S rRNA. The FISH technique identify, without extracting nucleic acids, active microbial cells at different phylogenetic levels (from domains to species) under an epifluorescence microscope. An example of the application of both methodologies to assessing the microbial community composition of soil samples from a phyto-assisted bioremediation experiment of a contaminated soil by polychlorinated biphenyls (PCBs) is reported.

12 páginas, 5 figuras.-- The original publication is available at www.springerlink.com, The herbicide terbuthylazine is widely used within the EU; however, its frequent detection in surface and groundwater, together with its intrinsic toxicological properties, may pose a risk both for human and environmental health. Organic amendments have recently been proposed as a possible herbicide sorbent in soil, in order to limit herbicide movement from soil to water. The environmental fate of terbuthylazine depends not only in its mobility but also in its persistence. The latter is directly dependent on microbial degradation. For this reason, the effects of pine and oak residues on terbuthylazine soil microbial community functioning and on the potential of this community for terbuthylazine degradation were studied. For this purpose, degradation kinetics, soil dehydrogenase activity and the number of live bacteria were assessed in a clay loam soil treated with terbuthylazine and either amended with pine or oak wood or unamended (sterilised and non-sterilised). At day 65, 85%of the herbicide applied still persisted in the sterile soil, 73 % in the pine-amended one and 63 % in the oak-amended and unamended ones. Pine residues increased the sorption of terbuthylazine to soil and hampered microbial degradation owing to its high terbuthylazine sorption capacity and a decrease in the bioavailability of the herbicide. On the contrary, in the presence of oak residues, the herbicide sorption did not increase significantly. The overall results confirm the active role of the soil microbial community in terbuthylazine degradation in amended and unamended soils and in a liquid enrichment culture performed using an aliquot of the same soil as the inoculum. In this clay loamsoil, in the absence of amendments, the herbicide was found to be quite persistent (t1/2>95 days), while in the enrichment culture, the same natural soil bacterial community was able to halve terbuthylazine in 24 days. The high terbuthylazine persistence in this soil was presumably ascribable to its texture and in particular to the mineralogy of the clay fraction., This work was funded by the CSIC/CNR Bilateral Agreement ‘Adsorption and degradation of pesticides in soils modified with low cost biomaterials: Study of the microbial communities responsible for the biodegradation’ (project reference 2006IT0022).

A preliminary ecological characterisation of an open quarry that had been used for the disposal of pharmaceutical wastes from a factory producing antibiotics was performed. Pharmaceutical wastes and groundwater samples were collected and analysed in order to assess both the bacterial community structure and functioning, and the contamination by organic compounds, including antibiotics. Bacterial abundance measured using the epifluorescence direct count method, cell viability measured by using two fluorescent dyes, species diversity measured by assessing the bacterial community structure using fluorescence in situ hybridisation (FISH) and soil microbial activity based on dehydrogenase activity were used as microbiological indicators to evaluate the ‘quality state’ of the area studied. The overall results show that groundwater has a low-quality state in terms of bacterial viability, activity and diversity, associated with trace contamination by antibiotics and chlorinated volatile organics.

The antiviral drug Tamiflu has received particular attention because of its recommended use against the influenza A H5N1 and H1N1 viruses. Given its resistance to degradation and its hydrophilicity the active metabolite, Oseltamivir Carboxylate (OC), is expected to enter the aquatic ecosystem from sewage treatment plants. In the present paper the bacterial community of surface water samples, treated with OC (1.5 mg L-1), was characterized by Fluorescence In Situ Hybridization (FISH) in microcosm experiments. The alpha-, beta- and gamma-Proteobacteria increased in OC-treated versus non-treated water samples during the incubation period, suggesting these bacterial groups had an active role in OC degradation.

The ability of soil and groundwater ecosystems to recover from chemical contamination is primarily dependent on the presence of a microbial community which has the ability to remove it. Nevertheless, there has been a little research into these communities because it is strictly dependent on methods capable of identifying and characterizing their community structure and functioning. The use of molecular methods makes it possible to overcome this kind of identification limitation. In this work, we applied the fluorescence in situ hybridization (FISH) method to different samples, such as soil and groundwater contaminated with s-triazine herbicides (simazine or terbuthylazine) and surface water treated with the pharmaceutical oseltamivir carboxylate (Tamiflu). We compared the bacterial community structure in the presence/absence of these xenobiotics. The use of 16S rRNA-targeted oligonucleotide probes, designed specifically for the main phylogenetic levels (Archaea, Bacteria, -, -, -, "-subdivision of Proteobacteria, Planctomycetes, Gram-positive bacteria with a high or low DNA GþC content, Cytophaga-Flavobacter-Bacteroides phylum, and sulfate-reducing bacteria), and a DAPI stain made it possible to assess the structure of the bacterial community and its changes in the presence of these xenobiotics in all the ecosystems studied.

A bacterial community in an aquifer contaminated by s-triazines was studied. Groundwater microcosms were treated with terbuthylazine at a concentration of 100 μg L−1 and degradation of the herbicide was assessed. The bacterial community structure (abundance and phylogenetic composition) and function (carbon production and cell viability) were analysed. The bacterial community was able to degrade the terbuthylazine; in particular, Betaproteobacteria were involved in the herbicide biotransformation. Identification of some bacterial isolates by PCR amplification of the 16S rRNA gene revealed the presence of two Betaproteobacteria species able to degrade the herbicide: Advenella incenata and Janthinobacterium lividum. PCR detection of the genes encoding s-triazine-degrading enzymes indicated the presence of the atzA and atzB genes in A. incenata and the atzB and atzC genes in J. lividum. The nucleotide sequences of the PCR fragments of the atz genes from these strains were 100% identical to the homologous genes of the Pseudomonas sp. strain ADP. In conclusion, the results show the potential for the use of a natural attenuation strategy in the treatment of aquifers polluted with the terbuthylazine. The two bacteria isolated could facilitate the implementation of effective bioremediation protocols, especially in the case of the significant amounts of herbicide that can be found in groundwater as a result of accidental spills.

We propose a new approach to evaluate the natural attenuation capacity of soil by using fluorescence in situ hybridization (FISH). A specific oligonucleotide probe AtzB1 was designed based on the sequence data of the atzB gene involved in the hydrolytic deamination of s-triazines; this gene, located in a multiple copy plasmid was detected by the optimized FISH protocol. Two agricultural soils (Lodi and Henares) with a history of simazine treatments, and two natural soils (Soto and Monza), without previous exposure to simazine, were studied. AtzB1 probe-target cells were found only in the agricultural soils and, in a greater percentage, in the Lodi soil, compared to the Henares one. Moreover, the greatest percentage of AtzB1 probe-target cells in Lodi was accompanied by a greater mineralization rate, compared to the Henares soil. The FISH method used in this study was suitable for the detection of simazine-degrading bacteria and could be a useful indicator of the potential of soil bioremediation.

In the semiarid Mediterranean regions, water scarcity represents a common physiological stress for microbial communities residing in river sediments. However, the effect of drying has not yet adequately been evaluated when analyzing riverine microbiological processes. The bacterial community structure (abundance, biomass, composition) and functioning (carbon production, live cell percentage) were assessed during experimental desiccation in microcosms with sediments from different Mediterranean temporary rivers (Tagliamento, Krathis, Mulargia, Pardiela). Our results showed that the overall responses to drying of the bacterial community were independent from sediment origin and strictly related to water content. During desiccation, a prompt decline (up to 100%) of the initial bacterial carbon production was followed by a slower decrease in abundance and biomass, with an overall reduction of 74% and 78%, respectively. By the end of the experiment, live cells were still abundant but depressed in their main metabolic functions, thus resulting in a drastic increase in the community turnover time. Only 14% of the initial live cell biomass was available in dry sediments to immediately start the reactivation of the aquatic microbial food web after the arrival of new water. Community composition analysis showed a relative increase in alpha- and beta-Proteobacteria, when passing from wet to dry conditions. Our results suggest that the occurrence of drought events could affect carbon cycling through the freshwater microbial compartment, by temporarily limiting microbial mineralization and altering bacterial community structure.

A plant-assisted bioremediation strategy was applied in an area located in Southern Italy, close to the city of Taranto, historically contaminated by polychlorinated biphenyls (PCBs) and heavy metals. A specific poplar clone (Monviso) was selected for its ability to promote organic pollutant degradation in the rhizosphere, as demonstrated elsewhere. Chemical and microbiological analyses were performed at the time of poplar planting in selected plots at different distances from the trunk (0.25-1m) and at different soil depths (0-20 and 20-40cm), at day 420. A significant decrease in PCB congeners and a reduction in all heavy metals was observed where the poplar trees were present. No evidence of PCB and heavy metal reduction was observed in the non poplar-vegetated soil. Microbial analyses (dehydrogenase activity, cell viability, microbial abundance) of the autochthonous microbial community showed an improvement in soil quality. In particular, microbial activity generally increased in the poplar-rhizosphere and a positive effect was observed in some cases at up to 1m distance from the trunk and up to 40cm depth. The Monviso clone was effective in promoting both a general decrease in contaminant occurrence and an increase in microbial activity in the chronically polluted area a little more than one year after planting.

In this work the degradation of the herbicides metolachlor, diuron, monuron and of the metabolites 2-ethyl-6-methylaniline (EMA), and 3,4-dichloroaniline (DCA) was assessed in laboratory experiments on microbiologically active and sterilized soils. Their leaching potentials were calculated, using Gustafson's equation, by determining their mobility (as Koc) and persistence (expressed as DT50). Lysimeter experiments were also conducted to assess the actual leaching of the studied herbicides in a cereal crop tillage area vulnerable to groundwater contamination. The data obtained from the field were compared to the laboratory results. Moreover, some compounds of particular concern were searched for in the groundwater located near the experimental area in order to evaluate actual contamination and to test the reliability of the leaching potential. The GUS index, computed on data from microbiologically active soil, shows monuron as a leacher compound, EMA and DCA as non-leachers, metolachlor and diuron as transient ones. The presence of metolachlor in the groundwater monitored, even at concentrations up to 0.1 μg/l, confirms the possibility that transient compounds can be leached if microbial activity has not completely occurred in active surface soil.