The paper reports a new route for the fabrication and determination of physicochemical properties and biological activity, of metallic silica-based nanostructure (Ag/SiO2, Cu/SiO2).

Pesticides are key stressors of soil microorganisms with reciprocal effects on ecosystem functioning. These effects have been mainly attributed to the parent compounds, while the impact of their transformation products (TPs) has been largely overlooked. We assessed, in a meadow soil (A),the transformation of iprodione and its toxicity on the (i) abundance of functional microbial groups, (ii) activity of key microbial enzymes and (iii) diversity of bacteria, fungi and ammonia-oxidizing microorganisms (AOM) using amplicon sequencing. 3,5-Dichloroaniline (3,5-DCA), the main iprodione TP, was identified as key explanatory factor for the persistent reduction in enzymatic activities and potential nitrification (PN), and for the observed structural changes in the bacterial and fungal community. The abundance of certain bacterial (, , and ) and fungal () groups were negatively correlated with 3,5-DCA. A subsequent study in a fallow agricultural soil (B) showed a limited formation of 3,5-DCA which concurred with the lack of effects on nitrification. Direct 3,5-DCA application in soil B induced a dose-dependent reduction of PN and NO-N, which recovered with time. assays with terrestrial AOM verified the greater toxicity of 3,5-DCA over iprodione. Nitrosotalea sinensis Nd2 was the most sensitive AOM to both compounds. Our findings build on previous evidence on the sensitivity of AOM to pesticides reinforcing their potential utilization as indicators of the soil microbial toxicity of pesticides in pesticide environmental risk analysis and stressing the need to consider the contribution of TPs in the toxicity of pesticides on the soil microbial community. Pesticide toxicity on soil microorganisms is an emerging issue in pesticide risk assessment, dictated by the pivotal role of soil microorganisms on ecosystem services. However, the focus has traditionally been on parent compounds, while transformation products (TPs) are largely overlooked. We tested the hypothesis that TPs can be major contributors on the soil microbial toxicity of pesticides, using, iprodione, and its main TP, 3,5-dichloroaniline, as model compounds. We demonstrated, by measuring functional and structural endpoints, that 3,5-dichloraniline and not iprodione was associated with adverse effects on soil microorganisms, with nitrification being mostly affected. Pioneering assays with relevant ammonia-oxidizing bacteria and archaea verified the greater toxicity of 3,5-dichloraniline. Our findings are expected to advance environmental risk assessment highlighting the potential of ammonia-oxidizing microorganisms as indicators of the soil microbial toxicity of pesticides and stressing the need to consider the contribution of TPs on pesticides soil microbial toxicity.

c Thiabendazole (TBZ), imazalil (IMZ), ortho-phenylphenol (OPP), diphenylamine (DPA), and ethoxyquin (EQ) are used in fruitpackaging plants (FPP) with the stipulation that wastewaters produced by their application would be depurated on site. However, no such treatment systems are currently in place, leading FPP to dispose of their effluents in agricultural land. We investigated the dissipation of those pesticides and their impact on soil microbes known to have a key role on ecosystem functioning. OPP and DPA showed limited persistence (50% dissipation time [DT 50 ], 0.6 and 1.3 days) compared to TBZ and IMZ (DT 50 , 47.0 and 150.8 days). EQ was rapidly transformed to the short-lived quinone imine (QI) (major metabolite) and the more persistent 2,4-dimethyl-6-ethoxyquinoline (EQNL) (minor metabolite). EQ and OPP exerted significant inhibition of potential nitrification, with the effect of the former being more persistent. This was not reflected in the abundance (determined by quantitative PCR [qPCR]) of the amoA gene of ammonia-oxidizing bacteria (AOB) and archaea (AOA). Considering the above discrepancy and the metabolic pattern of EQ, we further investigated the hypothesis that its metabolites and not only EQ were toxic to ammonia oxidizers. Potential nitrification, amoA gene abundance, and amoA gene transcripts of AOB and AOA showed that QI was probably responsible for the inhibition of nitrification. Our findings have serious ecological and practical implications for soil productivity and N conservation in agriculturally impacted ecosystems and stress the need to include metabolites and RNAbased methods when the soil microbial toxicity of pesticides is assessed. During postharvest handling, fruits are subjected to treatments with fungicides like thiabendazole (TBZ), imazalil (IMZ), and ortho-phenyl phenol (OPP) (1, 2) and antioxidants like diphenylamine (DPA) and ethoxyquin (EQ) (3), resulting in the production of large volumes of pesticide-contaminated wastewaters. The direct environmental discharge of those effluents without prior depuration entails a serious risk for the integrity of receiving ecosystems, considering the high aquatic toxicity of the pesticides (4, 5). This concern has been addressed by the European Commission (EC), and authorization for those pesticides was given with the stipulation "that an efficient treatment of the produced wastewaters should be operative at a local scale" (6, 7).Various processes and systems have been tested for the treatment of wastewaters produced by fruit-packaging plants (FPP) including adsorption onto activated carbon (8), photocatalytic degradation (9, 10), and biological degradation (11, 12). However, their high cost, their elevated technological requirements, and the frequent production of oxidized metabolites which are of unknown toxicity compared to the parent compound have hampered their full-scale implementation. Thus, to date effluents from FPP are either discharged in municipal wastewater treatment systems or they are disposed via land-spreading on the s...

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Environmental pollution by heavy metals has become a serious problem in the world. Phytoextraction, which is one of the plant-based technologies, has attracted the most attention for the bioremediation of soils polluted with these contaminants. The aim of this study was to determine whether the multiple-tolerant bacterium, Brevibacterium casei MH8a isolated from the heavy metal-contaminated rhizosphere soil of Sinapis alba L., is able to promote plant growth and enhance Cd, Zn, and Cu uptake by white mustard under laboratory conditions. Additionally, the ability of the rifampicin-resistant spontaneous mutant of MH8a to colonize plant tissues and its mechanisms of plant growth promotion were also examined. In order to assess the ecological consequences of bioaugmentation on autochthonous bacteria, the phospholipid fatty acid (PLFA) analysis was used. The MH8a strain exhibited the ability to produce ammonia, 1-amino-cyclopropane-1-carboxylic acid deaminase, indole 3-acetic acid and HCN but was not able to solubilize inorganic phosphate and produce siderophores. Introduction of MH8a into soil significantly increased S. alba biomass and the accumulation of Cd (208%), Zn (86%), and Cu (39%) in plant shoots in comparison with those grown in non-inoculated soil. Introduced into the soil, MH8a was able to enter the plant and was found in the roots and leaves of inoculated plants thus indicating its endophytic features. PLFA analysis revealed that the MH8a that was introduced into soil had a temporary influence on the structure of the autochthonous bacterial communities. The plant growth-promoting features of the MH8a strain and its ability to enhance the metal uptake by white mustard and its long-term survival in soil as well as its temporary impact on autochthonous microorganisms make the strain a suitable candidate for the promotion of plant growth and the efficiency of phytoextraction.