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.
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•Antibiotics affect the diversity of natural bacterial communities.•Biodegradation is a homeostatic response by the natural microbial community.•Antibiotics and antibiotic resistance genes (ARGs) are emerging contaminants.•ARGs are naturally found in the chromosomes of some environmental bacteria.•Antibiotics are signals that trigger microbial community functioning.
•Biodegradation is the main process for eliminating the majority of pharmaceuticals.•Pharmaceuticals can inhibit microbial activity.•Evidence of pharmaceutical effects on natural microbial processes ...is scarce.•Environmental microorganisms comprise an enormous reservoir of antibiotic resistance and biodegradative capability.
Environmental microorganisms play a key role in fundamental ecological processes such as biogeochemical cycling and organic contaminant degradation. Microorganisms comprise a large unexplored reservoir of genetic diversity and metabolic capability providing several ecosystem services, most importantly the maintenance of soil and water quality. Pharmaceutical occurrence in the environment can compromise microbial community structure and activities in different ways. The fate of a pharmaceutical in soil or water depends on numerous factors, including its inherent physic-chemical properties (e.g. water solubility, lipophilicity, vapour pressure), environmental factors and climate conditions (e.g. temperature, incident radiation, pH) and most importantly the presence and activity of microorganisms that possess the ability to biodegrade it. The presence of a natural microbial community is a necessary prerequisite for an effective response to the various chemicals that can contaminate an ecosystem. The recovery from contamination is only possible if toxicity does not hamper microbial activity. This review presents current knowledge on the effects on natural microbial communities of some pharmaceuticals and of some biocides commonly found as environmental microcontaminants.
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.
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The Aliivibrio fischeri bioassay was successfully applied in order to evaluate the acute effect of sulfamethoxazole (SMX), ciprofloxacin (CIP), chlortetracycline (CTC) and copper (Cu), alone ...or in binary, ternary, and overall mixture. The toxicity results are reported in terms of both effective concentrations, which inhibited 50% of the bacterium bioluminescence (EC50%), and in Toxic Units (TUs). The TUs were compared with predicted values obtained using the Concentration Addition model (CA). Finally, the toxicity of water extracts from a soil contaminated by the three antibiotics (7 mg Kg−1 each) in the presence/absence of copper (30 mg Kg−1) was also evaluated. Copper was the most toxic chemical (EC50: 0.78 mg L-1), followed by CTC (EC50: 3.64 mg L−1), CIP (96 mg L−1) and SMX (196 mg L−1). Comparing the TU and CA values of the mixtures, additive effects were generally found. However, a synergic action was recorded in the case of the CIP+Cu co-presence and antagonistic effects in the case of CTC+Cu and the ternary mixture (containing each antibiotic at 0.7 mg L−1), were identified. Soil water extracts did not show any toxicity, demonstrating the buffering ability of the soil to immobilize these chemicals.
Bioluminescence of the A. fischeri bacterium is a very sensitive biosensor of antibiotics and copper toxicity in single presence and mixture.
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.
Landslides recurrently impact the Italian territory, producing huge economic losses and casualties. Because of this, there is a large demand for monitoring tools to support landslide management ...strategies. Among the variety of remote sensing techniques, Interferometric Synthetic Aperture Radar (InSAR) has become one of the most widely applied for landslide studies. This work reviews a variety of InSAR-related applications for landslide studies in Italy. More than 250 papers were analyzed in this review. The first application dates back to 1999. The average production of InSAR-related papers for landslide studies is around 12 per year, with a peak of 37 papers in 2015. Almost 70% of the papers are written by authors in academia. InSAR is used (i) for landslide back analysis (3% of the papers); (ii) for landslide characterization (40% of the papers); (iii) as input for landslide models (7% of the papers); (iv) to update landslide inventories (15% of the papers); (v) for landslide mapping (32% of the papers), and (vi) for monitoring (3% of the papers). Sixty-eight percent of the authors validated the satellite results with ground information or other remote sensing data. Although well-known limitations exist, this bibliographic overview confirms that InSAR is a consolidated tool for many landslide-related applications.
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.
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•We have developed an analytical method to measure 13 benzodiazepines at environmental relevant concentrations.•We have measured 138 water samples from six European river basins and 31 rivers and their tributaries.•This study clearly shows that there are several benzodiazepines present in European surface waters at ng L−1 levels.
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•Ecotoxicity of SLES and some foaming agents on H. incongruens was determined.•SLES and ecotoxicity were measured in excavated soils from real construction sites.•Ecotoxicity depended ...on soil lithology and its capability to adsorb SLES.•This ostracod is a good bioindicator for the soil–water interface.•H. incongruens could be useful to assess soil toxicity in a test battery.
The production and consumption of surfactants are constantly increasing, and huge amounts are found in the environment as contaminants. Surfactants are widely used in domestic and industrial applications, including in tunnel-mechanized excavation of large-scale infrastructures (e.g. highways and railways). In the latter case, the commercial products are foaming agents containing the anionic surfactant sodium lauryl ether sulphate (SLES). Foaming agents are necessary for enhancing Tunnel Boring Machine-Earth Pressure Balance (TBM-EPB) performance. Consequently, there are SLES concentrations in excavated soils of which large quantities can have harmful effects on biota. SLES toxicity in the aquatic environment is well known; on the contrary, knowledge of its effects on soil organisms is quite limited. In order to better understand SLES ecotoxicity in soil, the standardized bioassay (ISO 14371:2012) with the crustacean Heterocypris incongruens, living in the soil–water interface, was used. The lethal concentrations of standard SLES (LC15: 120; LC50: 140 mg/L, respectively) and of three common commercial products used as foaming agents (LC50 varying from 275 to 3810 mg/L) were evaluated. Subsequently, the crustacean acute and sub-chronic effects (mortality and growth inhibition) were assessed in seven different excavated soils conditioned with various commercial products. In addition, SLES concentrations in each soil and in their soil water extract were also determined. Mortality was not recorded in soils conditioned with foaming agents; however, a growth inhibition (c.a. 61.6 %) was found for soils with a high fine fraction and conditioned with high amounts (≥2 L/m3 soil) of foaming agents. H. incongruens proved to be an appropriate bioassay for assessing the possible effects of high SLES concentrations in soil, especially when this surfactant is bound to soil.
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