Toxicity of three phenolic compounds and their mixtures on the gram-positive bacteria Bacillus subtilis in the aquatic environment

Modeling mixtures interactions in environmental toxicology

In the environment, organisms are exposed to mixtures of different toxicants, which may interact in ways that are difficult to predict when only considering each component individually. Adapting and expanding tools from pharmacology, the toxicology field uses analytical, graphical, and computational methods to identify and quantify interactions in multi-component mixtures. The two general frameworks are concentration addition, where components have similar modes of action and their effects sum together, or independent action, where components have dissimilar modes of action and do not interact. Other interaction behaviors include synergism and antagonism, where the combined effects are more or less than the additive sum of individual effects. This review covers foundational theory, methods, an in-depth survey of original research from the past 20 years, current trends, and future directions. As humans and ecosystems are exposed to increasingly complex mixtures of environmental contaminants, analyzing mixtures interactions will continue to become a more critical aspect of toxicological research.

Environmental and health impacts of functional graphenic materials and their ultrasonically altered products

Graphenic materials have excited the scientific community due to their exciting mechanical, thermal, and optoelectronic properties for a potential range of applications. Graphene and graphene derivatives have demonstrated application in areas stretching from composites to medicine; however, the environmental and health impacts of these materials have not been sufficiently characterized. Graphene oxide (GO) is one of the most widely used graphenic derivatives due to a relatively easy and scalable synthesis, and the ability to tailor the oxygen containing functional groups through further chemical modification. In this paper, ecological and health impacts of fresh and ultrasonically altered functional graphenic materials (FGMs) were investigated. Model organisms, specifically Escherichia coli, Bacillus subtilis, and Caenorhabditis elegans, were used to assess the consequences of environmental exposure to fresh and ultrasonically altered FGMs. FGMs were selected to evaluate the environmental effects of aggregation state, degree of oxidation, charge, and ultrasonication. The major findings indicate that bacterial cell viability, nematode fertility, and nematode movement were largely unaffected, suggesting that a wide variety of FGMs may not pose significant health and environmental risks.

Wide-genome selection of lactic acid bacteria harboring genes that promote the elimination of antinutritional factors

Anti-nutritional factors (ANFs) substances in plant products, such as indigestible non-starchy polysaccharides (α-galactooligosaccharides, α-GOS), phytate, tannins, and alkaloids can impede the absorption of many critical nutrients and cause major physiological disorders. To enhance silage quality and its tolerance threshold for humans as well as other animals, ANFs must be reduced. This study aims to identify and compare the bacterial species/strains that are potential use for industrial fermentation and ANFs reduction. A pan-genome study of 351 bacterial genomes was performed, and binary data was processed to quantify the number of genes involved in the removal of ANFs. Among four pan-genomes analysis, all 37 tested Bacillus subtilis genomes had one phytate degradation gene, while 91 out of 150 Enterobacteriacae genomes harbor at least one genes (maximum three). Although, no gene encoding phytase detected in genomes of Lactobacillus and Pediococcus species, they have genes involving indirectly in metabolism of phytate-derivatives to produce Myo-inositol, an important compound in animal cells physiology. In contrast, genes related to production of lectin, tannase and saponin degrading enzyme did not include in genomes of B. subtilis and Pediococcus species. Our findings suggest a combination of bacterial species and/or unique strains in fermentation, for examples, two Lactobacillus strains (DSM 21115 and ATCC 14869) with B. subtilis SRCM103689, would maximize the efficiency in reducing the ANFs concentration. In conclusion, this study provides insights into bacterial genomes analysis for maximizing nutritional value in plant-based food. Further investigations of gene numbers and repertories correlated to metabolism of different ANFs will help clarifying the efficiency of time consuming and food qualities.

Paracetamol degradation pathways in soil after biochar addition

Little is known about the effect of biochar on the degradation of paracetamol in soil, considering the ubiquity of this pollutant in the environment. Given the importance of the electrochemical properties of biochar for contaminant remediation, we investigated the influence of raw and designer redox-active biochars on paracetamol degradation in soil. Metabolite quantification indicated that a minimum of 53% of the spiked paracetamol was transformed in biochar-amended soil, resulting in the accumulation of different degradation products. The identification of these products allowed us to chart paracetamol degradation pathways in soil with and without biochar amendment. Some of the major degradation routes were observed to proceed via catechol and phenol, despite being previously described as having only a minor role in paracetamol metabolism. Additionally, a new transformation route from paracetamol to NAPQI was discovered in anaerobic soil originating from direct redox reactions on the surface of the designer biochars. These results may contribute to change our understanding of the environmental fate of paracetamol in soil and the role of biochar in its biodegradation.

The role of MOF based nanocomposites in the detection of phenolic compounds for environmental remediation- A review

Phenolic compounds would be the emerging pollutant by 2050, because of their wide spread applicability in daily life and therefore the adoption of suitable detection methods in which identification and separation of isomers is highly desirable. Owing to the fascinating features, Metal-organic framework (MOF), a class of reticular materials holds a large surface area with tunable shape and adjustable porosity will provide strong interaction with analytes through abundant functional groups resulting in high selectivity towards electrochemical determination of phenolic isomers. Nevertheless, the sensing performance can still be further improved by building MOF network (intrinsic resistance) with functional (conducting) materials, resulting in MOF based nanocomposite. Herein, this review provides the summary of MOF based nanocomposites for electrochemical sensing of phenolic compounds developed from 2015. In this review, we discussed the demerits of pristine MOF as electrode materials, and the requirement of new class of MOF with functional materials such as nanomaterials, carbon nanotubes, graphene and MXene. The history and evolution of MOF nanocomposite-based materials are discussed and also featured the impressive physical and chemical properties. Besides this review discusses the factors influencing the conducting pathway and mass transport of MOF based nanocomposite for enhanced sensing performance of phenolic compounds with suitable mechanistic illustrations. Finally, the major challenges governing the determination of phenolic compounds and the future advancements required for the development of MOF based electrodes for various applications are highlighted.

Road Runoff Characterization: Ecotoxicological Assessment Combined with (Non-)Target Screenings of Micropollutants for the Identification of Relevant Toxicants in the Dissolved Phase

Road runoff (RR) is an important vector of micropollutants towards groundwater and soils, threatening the environment and ecosystems. Through combined chemical and biological approaches, the purpose of this study was to get insights on specific toxicants present in RR from two sites differing by their traffic intensity and their toxicological risk assessment. Non-target screening was performed by HRMS on RR dissolved phase. Ecotoxicological risk was evaluated in a zebrafish embryos model and on rat liver mitochondrial respiratory chain. Specific HRMS fingerprints were obtained for each site, reflecting their respective traffic intensities. Several micropollutants, including 1,3-diphenylguanidine (DPG) and benzotriazole (BZT) were identified in greater concentrations at the high-traffic site. The origin of DPG was confirmed by analyzing HRMS fingerprints from shredded tires. RR samples from each site, DPG and BZT were of relatively low toxicity (no mortality) to zebrafish embryos, but all generated distinct and marked stress responses in the light–dark transition test, while DPG/BZT mixes abolished this effect. The moderate-traffic RR and DPG inhibited mitochondrial complex I. Our study highlights (i) the unpredictability of pollutants cocktail effect and (ii) the importance of a multi-approaches strategy to characterize environmental matrices, essential for their management at the source and optimization of depollution devices.

Spiderweb-inspired all-weather CoS quantum dots confined in N-doped carbon for boosted sulfate radical evolution

Inspired by the working principle of natural spiderweb and long-persistence phosphor, we have synthesized a spider-web-like nanocomposite in which the CoS quantum dots confined in N-doped carbon framework/carbon nanotube (CNTs)....

Biosynthesis of Organic Nanocomposite Using Pistacia vera L. Hull: An Efficient Antimicrobial Agent

Here presented a quick and easy synthesis of copper nanoparticles (CuNPs). Pistachio hull extract has been used as a reducing and stabilizing agent in the preparation of CuNPs. This biosynthesis is a kind of supporter of the environment because chemical agents were not used to making nanoparticles, and on the other hand, it prevents the release of pistachio waste in nature and its adverse effects on nature. The biosynthesized CuNPs and CuNPs/silver Schiff base nanocomposite (CSS NC) were characterized by UV-VIS spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS). CuNP and CSS NC antimicrobial activity was examined by both well diffusion and determination MIC methods against four bacteria Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa and two fungi Aspergillus Niger and Candida albicans. CuNPs and CSS NC showed significant antimicrobial activity on the samples, preventing the growth of bacteria and fungi at very low concentrations. CuNPs and CSS NC had the greatest effect on Escherichia coli bacteria and Aspergillus niger fungi. Phenolic compounds are one of the most important antioxidants that are involved in various fields, including pharmacy. Pistacia vera hull is a rich source of phenolic compounds. In this study, the most phenolic compound in Pistacia vera hull is gallic acid and rutin, which has been identified by HPLC analysis. In this study, Pistacia vera hull essential oil analysis was performed by the GC-MS method, in which α-pinene, D-limonene, and isobornyl acetate compounds constitute the highest percentage of Pistacia vera hull essential oil.

Effect of Pseudomonas moorei KB4 Cells' Immobilisation on Their Degradation Potential and Tolerance towards Paracetamol

Pseudomonas moorei KB4 is capable of degrading paracetamol, but high concentrations of this drug may cause an accumulation of toxic metabolites. It is known that immobilisation can have a protective effect on bacterial cells; therefore, the toxicity and degradation rate of paracetamol by the immobilised strain KB4 were assessed. Strain KB4 was immobilised on a plant sponge. A toxicity assessment was performed by measuring the concentration of ATP using the colony-forming unit (CFU) method. The kinetic parameters of paracetamol degradation were estimated using the Hill equation. Toxicity analysis showed a protective effect of the carrier at low concentrations of paracetamol. Moreover, a pronounced phenomenon of hormesis was observed in the immobilised systems. The obtained kinetic parameters and the course of the kinetic curves clearly indicate a decrease in the degradation activity of cells after their immobilisation. There was a delay in degradation in the systems with free cells without glucose and immobilised cells with glucose. However, it was demonstrated that the immobilised systems can degrade at least ten succeeding cycles of 20 mg/L paracetamol degradation. The obtained results indicate that the immobilised strain may become a useful tool in the process of paracetamol degradation.

Efficient Removal of Organic Pollutants by Metal-organic Framework Derived Co/C Yolk-Shell Nanoreactors: Size-Exclusion and Confinement Effect

Selective removal of organic pollutants from surface water with high efficiency is crucial in water purification. Here, yolk-shell Co/C nanoreactors (YSCCNs) are facilely synthesized via pyrolysis of controllably etched ZIF-67 by tannic acid, and their degradation performance on multiple pollutants is demonstrated. To present the structure-performance relationship between the designed nanocatalyst and the selective removal of organic pollutants, bisphenol A (BPA) was selected as the targeted pollutant with coexistence of humus acid (HA). For comparison, solid and hollow ZIF-67 derived Co/C nanoparticles denoted as SCCNs and HCCNs, were also tested. The results show that YSCCNs exhibit enhanced BPA degradation rate of 0.32 min^-1, which is 23.1% and 45.4% higher than that of HCCNs and SCCNs in HA (10 ppm) system. The essential improvement can be ascribed to the synergetic effects from shell layer (size-exclusion) and core/shell (confinement effect). The degradation mechanism and pathway are further confirmed by radical quenching experiments and liquid chromatography-mass spectrograph (LC-MS), respectively. In addition, some influential factors, including reaction temperature, pH value, and peroxymonosulfate (PMS) dosage are investigated in detail. This work provides a possible way to selectively remove target contaminant from multiple pollutants in complex water system.

Electrocoagulation and electrooxidation pre-treatment effect on fungal treatment of pistachio processing wastewater

The effect of electrochemical pre-treatment on fungal treatment of pistachio processing wastewater (PPW) was investigated. Electrocoagulation (EC) and electrooxidation (EO) were used as electrochemical pre-treatment step before fungal treatment of PPW. Aluminum (Al/Al), iron (Fe/Fe), and stainless steel (SS/SS) electrode pairs were selected as anode/cathode for EC whereas boron doped diamond (BDD/SS) was preferred as anode/cathode electrode pairs for EO experiments in this study. The impact of current density (50-300 A/m²) and operating time (0-240 min) were tested for chemical oxygen demand (COD) and total phenol removal. After pre-treatment of PPW, four different fungus species (Coriolus versicolor, Funalia trogii, Aspergillus carbonarius, and Penicillium glabrum) were tested for further treatment. Penicillium glabrum supplied maximum COD and total phenol removal efficiency compared to other fungus strains. The combined electrochemical-assisted fungal treatment process supplied 90.1% COD and 88.7% total phenol removal efficiency when supported with EO pre-treatment. Pre-treatment of PPW with EO method provided better results than EC method for fungal treatment. Operating cost of the combined process was calculated as 6.12 US$/m³. The results indicated that the proposed combined process supplied higher pollutant removal compared to the individual electrocoagulation, electrooxidation, and fungal treatment process.

Effects of typical flotation reagent on microbial toxicity and nickel bioavailability in soil

The combined toxicological effects of nickel (Ni) and butyl xanthate (BX), that is commonly used in flotation reagents for non-ferrous metals ore processing such as Ni, copper and lead ores, on soil microbial communities were studied by determining soil microbial activity, soil enzyme activities and Ni bioavailability. The results revealed that the exchangeable (EXC) and reducible (RED) fractions of Ni were higher in Ni/BX mixture than Ni alone, probably because BX reacts with Ni to form complexes that lead an increase in bioavailability of Ni. The presence of BX and Ni inhibited microbial activity and enzyme activities during the first 30-days. Then, from 30 days to 180 days, different trends were observed according to the condition: microbial activity was stimulated with BX alone while it was inhibited with Ni/BX mixture. This observation was supported by the fact that the inhibitory ratio (I) was higher for Ni/BX mixture than BX alone. Results showed that the sensitivity to one or both contaminants followed the order: urease (UA) > invertase (INV). EXC fraction of Ni/BX mixture were significantly correlated with UA, INV, I, peak power (P_peak) and peak time (T_peak), respectively (p < 0.01), suggesting that Ni bioavailability might explain the Ni toxicity against microbial communities under combined pollution conditions. Such observations allow us to better understand toxic effects of Ni pollution when accompanied with BX, facilitating precisely evaluation of potential risks in mining areas.

Phragmites australis - a helophytic grass - can establish successful partnership with phenol-degrading bacteria in a floating treatment wetland

Helophytic plants contribute significantly in phytoremediation of a variety of pollutants due to their physiological or biochemical mechanisms. Phenol, which is reported to have negative/deleterious effects on plant metabolism at concentrations higher than 500 mg/L, remains hard to be removed from the environmental compartments using conventional phytoremediation procedures. The present study aims to investigate the feasibility of using P. australis (a helophytic grass) in combination with three bacterial strains namely Acinetobacter lwofii ACRH76, Bacillus cereus LORH97, and Pseudomonas sp. LCRH90, in a floating treatment wetland (FTW) for the removal of phenol from contaminated water. The strains were screened based on their phenol degrading and plant growth promoting activities. We found that inoculated bacteria were able to colonize in the roots and shoots of P. australis, suggesting their potential role in the successful removal of phenol from the contaminated water. Pseudomonas sp. LCRH90 dominated the bacterial community structure followed by A. lowfii ACRH76 and B. cereus LORH97. The removal rate was significantly high when compared with the individual partners, i.e., plants and bacteria separately. The plant biomass, which was drastically reduced in the presence of phenol, recovered significantly with the inoculation of bacterial consortia. Likewise, highest reduction in chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total organic carbon (TOC) is achieved when both plants and bacteria were employed. The study, therefore, suggests that P. australis in combination with efficient bacteria can be a suitable choice to FTWs for phenol-degradation in water.

Prussian Blue Microcrystals with Morphology Evolution as a High-Performance Photo-Fenton Catalyst for Degradation of Organic Pollutants

The morphology-dependent property of crystal materials has aroused extensive attention and raised high requirements for subtly tailoring the morphology of micro-/nanocrystals. Herein, we develop an in situ etching method for preparation of Prussian blue (PB) microcrystals with morphology evolution by progressively increasing the concentration of chloroplatinic acid in the reaction system. These PB microcrystals with controllable morphologies are employed as photo-Fenton reagents to degrade organic pollutants. PB hexapods (PB-hpds) and PB hexapod stars present superior catalytic performance to pristine PB microcubes and other PB intermediates with truncated corners or edges because of their high specific surface areas and adequate exposure of Fe^III-NC coordination active sites. In the reusability test, the reused PB-hpds present more efficient catalytic performance for rhodamine B decomposition compared with the pristine catalyst. According to more investigations, the reasonable mechanism is proposed that Fe^III-NC exhibits higher catalytic activity than Fe^II-CN in the specific coordination environment. The increased content of surface Fe^III-NC coordination active sites is the key factor in accelerating the decomposition of H₂O₂ and enhancing the photo-Fenton performance of PB-hpds. Several operating parameters including catalyst dosage, H₂O₂ concentration, pH value, and reaction temperature are evaluated in detail. Classical quenching experiments and electron paramagnetic resonance measurements further reveal that HO^• should be responsible for high performance of catalysts. This work will be significant for tailoring the morphology of the materials and arousing more attention to enhance the stability and reusability of catalysts.

Formulation and chemical characterization of Clerodendrum infortunatum leaf extract in relation to anti-fungal activity

The study explored to develop an eco-friendly herbal fungicide from chloroform extract of Clerodendrum infortunatum leaves. The extract upon activity guided purification using flash chromatography yielded eight fractions F3 through F10. Total phenol and flavonoid contents in the fractions ranged from 0.12-48.25 mg GAE/g and 0.03–25.29 mg QE/g. LC-MS/MS analysis confirmed the identification of seven phenolic acids across different fractions, the total of which varied between 0 and 2.17 mg/g. Emulsifiable Concentrate (20%) formulation was made with the extract and fractions and tested against Phomopsis vexans causing fruit rot disease in brinjal. Of the various fractions, F8 displayed highest antifungal activity (ED₅₀ = 46.8 μg/ml). Antifungal activity of leaf extract/fractions was correlated with total phenol, total flavonoid and total phenolic acids (r = -0.60 to -0.69). Among the phenolic acids, benzoic acid showed maximum antifungal activity followed by t-cinnamic acid. The relationship between phenolic composition and activity is also reported.

Influence of Bisphenol A on the transport and deposition behaviors of bacteria in quartz sand

The influence of Bisphenol A (BPA) on the transport and deposition behaviors of bacteria in quartz sand was examined in both NaCl (10 and 25 mM) and CaCl₂ solutions (1.2 and 5 mM) by comparing the breakthrough curves and retained profiles of cell with BPA in suspensions versus those without BPA. Gram-negative Escherichia coli and Gram-positive Bacillus subtilis were employed as model cells in the present study. The extended Derjaguin-Landau-Verwey-Overbeek interaction energy calculation revealed that the presence of BPA in cell suspensions led to a lower repulsive interaction between the cells and the quartz sand. This suggests that, theoretically, increased cell deposition on quartz sand would be expected in the presence of BPA. However, under all examined solution conditions, the presence of BPA in cell suspensions increased transport and decreased deposition of bacteria in porous media regardless of cell type, ionic strength, ion valence, the presence or absence of extracellular polymeric substances. We found that competition by BPA through hydrophobicity for deposition sites on the quartz sand surfaces was the sole contributor to the enhanced transport and decreased deposition of bacteria in the presence of BPA.

Suitability of olive oil washing water as an electron donor in a feed batch operating bio-electrochemical system

Olive oil washing water derived from the two-phase manufacturing process was assessed as an electron donor in a bio-electrochemical system (BES) operating at 35 ºC. Start-up was carried out by using acetate as a substrate for the BES, reaching a potential of around +680 mV. After day 54, BES was fed with olive oil washing water. The degradation of olive oil washing water in the BES generated a maximum voltage potential of around +520 mV and a Chemical Oxygen Demand (COD) removal efficiency of 41%. However, subsequent loads produced a decrease in the COD removal, while current and power density diminished greatly. The deterioration of these parameters could be a consequence of the accumulation of recalcitrant or inhibitory compounds, such as phenols. These results demonstrated that the use of olive oil washing water as an electron donor in a BES is feasible, although it has to be further investigated in order to make it more suitable for a real application.

Toxicity of nickel to soil microbial community with and without the presence of its mineral collectors-a calorimetric approach

The toxicity of nickel and three of its main collectors, sodium isopropyl xanthate (SIPX), sodium ethyl xanthate (SEX), and potassium ethyl xanthate (PEX) to soil microbial activity, was analyzed, individually and as a binary combination of nickel and each of the collectors. The investigation was performed through the microcalorimetric analysis method. For the single chemicals, all power-time curves exhibited lag, exponential, stationary, and death phases of microbial growth. Different parameters exhibited a significant adverse effect of the analyzed chemicals on soil microbial activity, with a positive relationship between the inhibitory ratio and the chemical dose (p < 0.05 or p < 0.01). A peak power reduction level of 24.23% was noted for 50 μg g^-1 soil in the case of Ni while for the mineral collectors, only 5 μg g^-1 soil and 50 μg g^-1 soil induced a peak power reduction level of over 35 and 50%, respectively, in general. The inhibitory ratio ranged in the following order: PEX > SEX > SIPX > Ni. Similar behavior was observed with the mixture toxicity whose inhibitory ratio substantially decreased (maximum decrease of 38.35%) and slightly increased (maximum increase of 15.34%), in comparison with the single toxicity of mineral collectors and nickel, respectively. The inhibitory ratio of the mixture toxicity was positively correlated (p < 0.05 or p < 0.01) with the total dose of the mixture. In general, the lesser and higher toxic effects are those of mixtures containing SIPX and PEX, respectively.

Effects of gamma radiation on cork wastewater: Antioxidant activity and toxicity

A comprehensive assessment of the toxicity and antioxidant activity of cork boiling wastewater and the effects of gamma radiation on these parameters was performed. Antioxidant activity was evaluated using different methodologies as DPPH radical scavenging activity, reducing power and inhibition of β-carotene bleaching. The results have shown that gamma radiation can induce an increase on the antioxidant activity of cork boiling wastewater. Toxicity tests were performed to access the potential added value of the irradiated wastewaters and/or minimization of the impact for discharge in the environment. Two different methods for toxicity evaluation were followed, bacterial growth inhibition test and cytotoxicity assay, in order to predict the behavior of different cells (prokaryotic and eukaryotic) in the presence of cork wastewater. Non-treated cork boiling wastewater seemed to be non-toxic for prokaryotic cells (Pseudomonas fluorescens and Bacillus subtilis) but toxic for eukaryotic cells (A549 human cells and RAW264.7 mouse cells). The gamma radiation treatment at doses of 100 kGy appeared to increase the toxicity of cork compounds for all tested cells, which could be related to a toxic effect of radiolytic products of cork compounds in the wastewaters.

Catechol Removal from Aqueous Media Using Laccase Immobilized in Different Macro- and Microreactor Systems

Laccase belongs to the group of enzymes that are capable to catalyze the oxidation of phenols. Since the water is only by-product in laccase-catalyzed phenol oxidations, it is ideally "green" enzyme with many possible applications in different industrial processes. To make the oxidation process more sustainable in terms of biocatalyst consumption, immobilization of the enzyme is implemented in to the processes. Additionally, when developing a process, choice of a reactor type plays a significant role in the total outcome.In this study, the use of immobilized laccase from Trametes versicolor for biocatalytic catechol oxidation was explored. Two different methods of immobilization were performed and compared using five different reactor types. In order to compare different systems used for catechol oxidation, biocatalyst turnover number and turnover frequency were calculated. With low consumption of the enzyme and good efficiency, obtained results go in favor of microreactors with enzyme covalently immobilized on the microchannel surface.

Valorization of treated olive mill wastewater in fertigation practice

Olive mill wastewater (OMW) brings about a major environmental problem in Tunisia as well as in the other Mediterranean countries. Its strong organic load and its toxicity due to the presence of complex phenolic compounds have dire effects when applied to soil. To overcome this difficulty, the OMW pretreatment was investigated in the present work using the Fenton oxidation reaction with zero-valent iron. Then, this pretreated wastewater was valorized in fertigation practice. The effects of the addition of different concentrations of both treated and raw OMW on soil and cropping system were investigated. The treatment by Fenton oxidation with zero-valent iron could reduce 50 % of COD and decrease 53 % of phenolic compounds. OMW application had a temporary effect on the soil pH and EC. The results showed that the evolution of soil pH and EC was related to the organic matter of the soil which depends on the spread concentrations of raw or treated OMW. After 15-day incubation period, the soil pH and EC tended to stabilize and return to the control level. Moreover, this stabilization is faster in treated OMW than that in raw OMW especially for concentrations as high as 3 and 4 %. Plants cultivated with treated OMW showed an increase in their germination. The results pointed an improvement in the stem length of plants which is almost similar to that of the control for both pea and tomato, especially for high concentrations of 3 and 4 %.

Influence of Perfluorooctanoic Acid on the Transport and Deposition Behaviors of Bacteria in Quartz Sand

The significance of perfluorooctanoic acid (PFOA) on the transport and deposition behaviors of bacteria (Gram-negative Escherichia coli and Gram-positive Bacillus subtilis) in quartz sand is examined in both NaCl and CaCl2 solutions at pH 5.6 by comparing both breakthrough curves and retained profiles with PFOA in solutions versus those without PFOA. All test conditions are found to be highly unfavorable for cell deposition regardless of the presence of PFOA; however, 7%-46% cell deposition is observed depending on the conditions. The cell deposition may be attributed to micro- or nanoscale roughness and/or to chemical heterogeneity of the sand surface. The results show that, under all examined conditions, PFOA in suspensions increases cell transport and decreases cell deposition in porous media regardless of cell type, presence or absence of extracellular polymeric substances, ionic strength, and ion valence. We find that the additional repulsion between bacteria and quartz sand caused by both acid-base interaction and steric repulsion as well as the competition for deposition sites on quartz sand surfaces by PFOA are responsible for the enhanced transport and decreased deposition of bacteria with PFOA in solutions.

Copper nanoparticles supported on diamond nanoparticles as a cost-effective and efficient catalyst for natural sunlight assisted Fenton reaction

A series of catalysts consisting of Cu nanoparticles (NPs) supported on diamond nanoparticles (D) were obtained by polyol reduction of Cu(NO₃)₂ in the presence of D.

Impact of hydroquinone used as a redox effector model on potential denitrification, microbial activity and redox condition of a cultivable soil

In this microcosm study, we analyzed the effect produced by hydroquinone on the expression of soil biological denitrification, in relation to the redox state of the soil, both in terms of intensity factor (Eh') and capacity factor (amount of oxidized or reduced compounds). The supplementation of an Argiudoll soil with hydroquinone decreased the soil apparent reduction potential (Eh') and soil dehydrogenase activity (formazan production from tetrazolium chloride reduction; redox capacity factor), the relationship between both factors being highly significative, r=0.99 (p<0.001). The bacterial population (measured by colony forming units) increased, and the production of N2O was greater (p<0.001) at 200 and 400μg/g dry soil doses. Furthermore, there was an inverse relationship between soil dehydrogenase activity and the number of bacteria (r=-0.82; p<0.05), increased denitrification activity and changes in the CO2/N2O ratio value. These results suggest that hydroquinone at supplemented doses modified the soil redox state and the functional structure of the microbial population. Acetate supplementation on soil with hydroquinone, to ensure the availability of an energy source for microbial development, confirmed the tendency of the results obtained with the supplementation of hydroquinone alone. The differences observed at increased doses of hydroquinone might be explained by differences on the hydroquinone redox species between treatments.

Investigation of olive mill wastewater (OMW) ozonation efficiency with the use of a battery of selected ecotoxicity and human toxicity assays

The effects of olive mill wastewater (OMW) on a battery of biological assays, before and during the ozonation process, were investigated in order to assess ozone's efficiency in removing phenolic compounds from OMW and decreasing the concomitant OMW toxicity. Specifically, ozonated-OMW held for 0, 60, 120, 300, 420, 540min in a glass bubble reactor, showed a drastic reduction of OMW total phenols (almost 50%) after 300min of ozonation with a concomitant decrease of OMW toxicity. In particular, the acute toxicity test primarily performed in the fairy shrimp Thamnocephalus platyurus (Thamnotoxkit F™ screening toxicity test) showed a significant attenuation of OMW-induced toxic effects, after ozonation for a period of 120 and in a lesser extent 300min, while further treatment resulted in a significant enhancement of ozonated-OMW toxic effects. Furthermore, ozonated-OMW-treated mussel hemocytes showed a significant attenuation of the ability of OMW to cause cytotoxic (obtained by the use of NRRT assay) effects already after an ozonation period of 120 and to a lesser extent 300min. In accordance with the latter, OMW-mediated oxidative (enhanced levels of superoxide anions and lipid peroxidation by-products) and genotoxic (induction of DNA damage) effects were diminished after OMW ozonation for the aforementioned periods of time. The latter was also revealed by the use of cytokinesis block micronucleus (CBMN) assay in human lymphocytes exposed to different concentrations of both raw- and ozonated-OMW for 60, 120 and 300min. Those findings revealed for a first time the existence of a critical time point during the OMW ozonation process that could be fundamentally used for evaluating OMW ozonation as a pretreatment method of OMW.

Laccase immobilization on the electrode surface to design a biosensor for the detection of phenolic compound such as catechol

Biosensors based on the coupling of a biological entity with a suitable transducer offer an effective route to detect phenolic compounds. Phenol and phenolic compounds are among the most toxic environmental pollutants. Laccases are multi-copper oxidases that can oxide phenol and phenolic compounds. A method is described for construction of an electrochemical biosensor to detect phenolic compounds based on covalent immobilization of laccase (Lac) onto polyaniline (PANI) electrodeposited onto a glassy carbon (GC) electrode via glutaraldehyde coupling. The modified electrode was characterized by voltammetry, Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) techniques. The results indicated that laccase was immobilized onto modified GC electrode by the covalent interaction between laccase and terminal functional groups of the glutaraldehyde. The laccase immobilized modified electrode showed a direct electron transfer reaction between laccase and the electrode. Linear range, sensitivity, and detection limit for this biosensor were 3.2 × 10(-6) to 19.6 × 10(-6)M, 706.7 mAL mol(-1), 2.07 × 10(-6)M, respectively.

Antibacterial evaluation of flavonoid compounds against E. coli by microcalorimetry and chemometrics

Fighting against multidrug-resistant bacteria requires reliable methods to evaluate the effect of antibacterial agents. As a universal, non-destructive, and highly sensitive tool, microcalorimetry has been used in many biological investigations to provide continuous real-time monitoring of the metabolic activity. This method, based on heat-flow output, was used to evaluate the influence of two flavonoid compounds (liquiritigenin and liquiritin) on Escherichia coli. Some crucial information, such as the thermogenic power-time curve and thermokinetic parameters of E. coli growth affected by the two compounds, was obtained and further studied by chemometric techniques including similarity analysis, multivariate analysis of variance, and principal component analysis. By comparing the values of two main parameters, k 2 (growth rate constant of the second exponential phase) and Q 1 (heat output of the first exponential growth phase) of E. coli based on the box and whisker plot, liquiritigenin and liquiritin could be differentiated according to their antibacterial effects; liquiritin with IC50 (half-inhibitory concentration) of 198.6 μg mL(-1) expressed a stronger antibacterial effect than liquiritigenin with IC50 of 337.8 μg mL(-1). The glucoside group in liquiritin containing four additional free hydroxyls in the diphenylpropane skeleton was crucial for inducing the antibacterial effect. Liquiritin might be a promising candidate against E. coli. This study provides a valuable method for searching for novel antibacterial agents using microcalorimetry with chemometrics.

Adhesive and sealant interfaces for general surgery applications

The main functions of biological adhesives and sealants are to repair injured tissues, reinforce surgical wounds, or even replace common suturing techniques. In general surgery, adhesives must match several requirements taking into account clinical needs, biological effects, and material features; these requirements can be fulfilled by specific polymers. Natural or synthetic polymeric materials can be employed to generate three-dimensional networks that physically or chemically bind to the target tissues and act as hemostats, sealants, or adhesives. Among them, fibrin, gelatin, dextran, chitosan, cyanoacrylates, polyethylene glycol, and polyurethanes are the most important components of these interfaces; various aspects regarding their adhesion mechanisms, mechanical performance, and resistance to body fluids should be taken into account to choose the most suitable formulation for the target application. This review aims to describe the main adhesives and sealant materials for general surgery applications developed in the past decades and to highlight the most important aspects for the development of future formulations.

Toxicity of perfluorooctanoic acid to Pseudomonas putida in the aquatic environment

Perfluorinated compounds are potential persistent organic pollutants which attracted much concerns in recent years. Thus relevant toxicity data of perfluorooctanoic acid (PFOA) are vitally important for identification of possible risk in the aquatic environment. In the present study, the acute toxic effect of PFOA in the absence and presence of either chromium (III) or tetra butyl ammonium (TBA) towards Pseudomonas putida in the aquatic environment was investigated by microcalorimetry. The thermokinetic parameters including growth rate constant (k), inhibitory ratio, and half inhibitory concentration, were calculated and compared using the data obtained from the power-time curves. Our work revealed the toxicity of PFOA under three experimental conditions in a descending sequence: PFOA, PFOA+Cr(3+), and PFOA+TBA. The results highlighted that the presence of un-ionized NH3 in the test solutions could not be a potential significant contributor to the observed toxicity of PFOA. In addition, PFOA interacted antagonistically with Cr(3+) and TBA. TBA was found to substantially enhance the surface pressure of PFOA which could be related with the toxicity of PFOA. The higher surface pressure caused for the reduction in toxicity. Thus the results highlighted the potential toxicological risk associated with this surfactant in the aquatic ecosystems.

A strategy for trade monitoring and substitution of the organs of threatened animals

The use of threatened animals as a source of traditional medicines is accelerating the extinction of such species and imposes great challenges to animal conservation. In this study, we propose a feasible strategy for the conservation of threatened medicinal animals that combines trade monitoring and the search for substitutes. First, DNA barcoding provides a powerful technique for monitoring the trade of animal species, which helps in restricting the excessive use and illegal trade of such species. Second, pharmacological tests have been adopted to evaluate the biological equivalence of threatened and domestic animals; based on such testing, potential substitutes are recommended. Based on a review of threatened animal species and their substitutes, we find that the search for substitutes deserves special attention; however, this work is far from complete. These results may be of great value for the conservation of threatened animals and maintaining the heritage of traditional medicine.

Hydroquinone: environmental pollution, toxicity, and microbial answers

Hydroquinone is a major benzene metabolite, which is a well-known haematotoxic and carcinogenic agent associated with malignancy in occupational environments. Human exposure to hydroquinone can occur by dietary, occupational, and environmental sources. In the environment, hydroquinone showed increased toxicity for aquatic organisms, being less harmful for bacteria and fungi. Recent pieces of evidence showed that hydroquinone is able to enhance carcinogenic risk by generating DNA damage and also to compromise the general immune responses which may contribute to the impaired triggering of the host immune reaction. Hydroquinone bioremediation from natural and contaminated sources can be achieved by the use of a diverse group of microorganisms, ranging from bacteria to fungi, which harbor very complex enzymatic systems able to metabolize hydroquinone either under aerobic or anaerobic conditions. Due to the recent research development on hydroquinone, this review underscores not only the mechanisms of hydroquinone biotransformation and the role of microorganisms and their enzymes in this process, but also its toxicity.

Are deep eutectic solvents benign or toxic?

In continuation of investigation for environmentally benign protocol for new solvents termed deep eutectic solvents (DESs), it is herein reported results concerning the toxicity and cytotoxicity of choline chloride (ChCl) based DESs with four hydrogen bond donors including glycerine, ethylene glycol, triethylene glycol and urea. The toxicity was investigated using two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity effect was tested using the Artemia salina leach. It was found that there was no toxic effect for the tested DESs on all of the studied bacteria confirming their benign effects on these bacteria. Nevertheless, it was found that the cytotoxicity of DESs was much higher than their individual components (e.g. glycerine, ChCl) indicating that their toxicological behavior is different. For our best knowledge this is the first time that toxicity and cytotoxicity of DESs were studied. The toxicity and cytotoxicity of DESs varied depending on the structure of components. Careful usage of the terms non-toxicity and biodegradability must be considered. More investigation on this matter is required.

Subcellular distribution of fluoranthene in Chlorella vulgaris with the presence of cetyltrimethylammonium chloride

This study explored the possible mechanism of the joint toxicity of binary mixtures of cetyltrimethylammonium chloride (CTAC) and fluoranthene (Flu) to the green alga Chlorella vulgaris by examining the subcellular distribution of Flu within the alga. The joint action of CTAC (100 μg L(-1)) and Flu (0-200 μg L(-1)) on the algae changed from a synergetic effect (0-50 μg L(-1)) to an antagonistic effect (50-200 μg L(-1)) with an increase of the Flu concentration. The Flu uptake was enhanced by the presence of CTAC through the intracellular detection of Flu. Furthermore, the highest amount of Flu bound to the cytosol, whereas the least amount bound to the cellular debris when synergistic effect was observed at 2.5 μg L(-1) Flu. However, the highest amount of Flu bound to the cellular debris, whereas the least amount bound to the organelles when antagonistic effect was displayed at 200 μg L(-1) Flu. The different subcellular distribution of Flu may affect the uptake of the highly toxic CTAC by the algae in the binary mixture, and consequently lead to a different level of CTAC toxicity. The abovementioned results indicate that the subcellular distribution of chemicals can be used to elucidate possible mechanisms for the joint toxicity of their binary mixtures to aquatic organisms.

Simulation and prediction of phenolic compounds fate in Songhua River, China

The demand for numerical models to simulate and predict the transport and fate of organic pollutants in the environment is a reflection of certain restrictions of experimental research. Various phenolic pollutants have been detected at different concentration levels in the Songhua River, China. A multimedia fate model is coupled with the kinematic wave transport equations to accurately and simply characterize dynamic water flow, velocity and depth. The resulting model is applied to describe the temporal and spatial behavior of eight phenol compounds in the Songhua River. The predictive power of this model is evaluated by statistical tests using field observations during different hydrological seasons of the year 2007. The goodness-of-fit of model prediction for phenolic contaminants is, in general, agreeable. For one focal compound, the pathways and mass fluxes from the river system to the surrounding environment are also evaluated. Uncertainty analysis is performed by Monte Carlo stimulation to judge the influence of variability of input parameters on modeled results. The results indicate that the model has the ability to provide decision makers with valuable reference data for consideration of water pollution controls. Model simulation indicates that phenolic pollution in the river during the low-flow period of 2009 is remarkably reduced when compared to the same period of 2007.

Olive oil mill wastewaters before and after treatment: a critical review from the ecotoxicological point of view

The olive oil mill wastewater (OMW) is a problematic and polluting effluent which may degrade the soil and water quality, with critical negative impacts on ecosystems functions and services provided. The main purpose of this review paper is presenting the state of the art of OMW treatments focusing on their efficiency to reduce OMW toxicity, and emphasizing the role of ecotoxicological tests on the evaluation of such efficiency before the up-scale of treatment methodologies being considered. In the majority of research works, the reduction of OMW toxicity is related to the degradation of phenolic compounds (considered as the main responsible for the toxic effects of OMW on seed germination, on bacteria, and on different species of soil and aquatic invertebrates) or the decrease of chemical oxygen demand content, which is not scientifically sound. Batteries of ecotoxicological tests are not applied before and after OMW treatments as they should be, thus leading to knowledge gaps in terms of accurate and real assessment of OMW toxicity. Although the toxicity of OMW is usually high, the evaluation of effects on sub-lethal endpoints, on individual and multispecies test systems, are currently lacking, and the real impacts yielded by its dilution, in freshwater trophic chains of receiving systems can not be assessed. As far as the terrestrial compartment is considered, ecotoxicological data available include tests only with plants and the evaluation of soil microbial parameters, reflecting concerns with the impacts on crops when using OMW for irrigation purposes. The evaluation of its ecotoxicity to other edaphic species were not performed giving rise to a completely lack of knowledge about the consequences of such practice on other soil functions. OMW production is a great environmental problem in Mediterranean countries; hence, engineers, chemists and ecotoxicologists should face this problem together to find an ecologically friend solution.

Sunlight-assisted Fenton reaction catalyzed by gold supported on diamond nanoparticles as pretreatment for biological degradation of aqueous phenol solutions

Gold nanoparticles supported on Fenton-treated diamond nanoparticles (Au/DNPs) have been reported as one of the most efficient solid catalysts effecting the Fenton reaction, achieving a turnover number (TON) as high as 321,000. However, at room temperature the main limitation for the catalytic activity of Au/DNPs is the pH of the solution, which should be less than 5. In this paper, we report that exposure of Au/DNPs to sunlight enhances the catalytic activity of Au/DNPs up to the point that it can promote the Fenton reaction at room temperature even at slightly basic pH values. Also, in addition to performing a deep Fenton treatment and considering that the excess of H(2)O(2) used in the process should be minimized, we have achieved in our study, using a mild Fenton reaction promoted by Au/DNPs under sunlight irradiation, an optimum in the biodegradability, a minimum in the ecotoxicity, and no toxicity for the Vibrio fischeri test. The results have shown that, by using an H(2)O(2) -to-phenol molar ratio of 5.5 or higher, it is possible to achieve a high biodegradability as well as a complete lack of ecotoxicity and of Vibrio fischeri toxicity. The stability of Au/DNPs was confirmed by analyzing the gold leached to the solution and by performing four consecutive reuses of the catalyst with initial pH values ranging from 4 to 8. It was observed that, after finishing the reaction and exhaustive washings with basic aqueous solutions, the initial reaction rate of the used catalyst is recovered to the value exhibited by the fresh solid. Overall, our study shows that the synergism between catalysis and photocatalysis can overcome the limitations found for dark catalytic reactions and that the reaction parameters can be optimized to effect mild Fenton reactions aimed at increasing biodegradability in biorecalcitrant waste waters.

Comparison of various easy-to-use procedures for extraction of phenols from apricot fruits

Phenols are broadly distributed in the plant kingdom and are the most abundant secondary metabolites of plants. Plant polyphenols have drawn increasing attention due to their potential antioxidant properties and their marked effects in the prevention of various oxidative stress associated diseases such as cancer. The objective of this study was to investigate a suitable method for determination of protocatechuic acid, 4-aminobenzoic acid, chlorogenic acid, caffeic acid, vanillin, p-coumaric acid, rutin, ferulic acid, quercetin, resveratrol and quercitrin from apricot samples. A high-performance liquid chromatograph with electrochemical and UV detectors was used. The method was optimized in respect to both the separation selectivity of individual phenolic compounds and the maximum sensitivity with the electrochemical detection. The lowest limits of detection (3 S/N) using UV detection were estimated for ferulic acid (3 µM), quercitrin (4 µM) and quercetin (4 µM). Using electrochemical detection values of 27 nM, 40 nM and 37 nM were achieved for ferulic acid, quercitrin and quercetin, respectively. It follows from the acquired results that the coulometric detection under a universal potential of 600 mV is more suitable and sensitive for polyphenols determination than UV detection at a universal wavelength of 260 nm. Subsequently, we tested the influence of solvent composition, vortexing and sonication on separation efficiency. Our results showed that a combination of water, acetone and methanol in 20:20:60 ratio was the most effective for p-aminobenzoic acid, chlorgenic acid, caffeic acid, protocatechuic acid, ferulic acid, rutin, resveratrol and quercetin, in comparison with other solvents. On the other hand, vortexing at 4 °C produced the highest yield. Moreover, we tested the contents of individual polyphenols in the apricot cultivars Mamaria, Mold and LE-1075. The major phenolic compounds were chlorgenic acid and rutin. Chlorgenic acid was found in amounts of 2,302 mg/100 g in cultivar LE-1075, 546 mg/100 g in cultivar Mamaria and 129 mg/100 g in cultivar Mold. Generally, the cultivar LE-1075 produced the highest polyphenol content values, contrary to Mold, which compared to cultivar LE-1075 was quite poor from the point of view of the phenolics content.

A comparative cytotoxicity study of isomeric alkylphthalates to metabolically variant bacteria

This work investigated the toxicity of two isomeric alkylphthalates, i.e., di-n-octyl phthalate (DOP) and di-2-ethylhexyl phthalate (DEHP) to two model bacteria, Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), which have been previously used to study the toxicity of environmental pollutants. Microcalorimetry was used as the key analytical tool alongside scanning electron microscopy (SEM) and traditional microbiology techniques. The thermokinetic parameters from microcalorimetry showed that the phthalates had a biphasic effect on the metabolic activities of the bacteria; serving as energy sources for the bacteria thereby stimulating their growth at low dosages (< or = 150 microg/mL), but displaying inhibitory effects at higher dosages (> or = 300 microg/mL), indicated by a sharp decrease in growth rate constants at 450 microg/mL. The SEM revealed that the bacterial cells were morphological deformed, with shrunk cells and elongated strands at 600 microg/mL of both phthalates. The elongated strands inferred that the phthalates inhibited the reproductive processes of the bacteria by possibly impeding some stages of cell division. The half inhibitory concentrations of the phthalates showed that DEHP was more toxic than DOP. Additionally, E. coli, a facultative anaerobe, was more susceptible to the toxic effects of phthalates than B. subtilis, an obligate aerobe capable of forming endospores crucial for tolerating extreme environmental conditions.