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Per- and polyfluoroalkyl substances (PFASs) from aqueous film forming foams (AFFFs) can hinder bioremediation of co-contaminants such as trichloroethene (TCE) and benzene, toluene, ethylbenzene, and xylene (BTEX). Anaerobic dechlorination can require bioaugmentation of Dehalococcoides, and for BTEX, oxygen is often sparged to stimulate in situ aerobic biodegradation. We tested PFAS inhibition to TCE and BTEX bioremediation by exposing an anaerobic TCE-dechlorinating coculture, an aerobic BTEX-degrading enrichment culture, and an anaerobic toluene-degrading enrichment culture to n-dimethyl perfluorohexane sulfonamido amine (AmPr-FHxSA), perfluorohexane sulfonamide (FHxSA), perfluorohexanesulfonic acid (PFHxS), or nonfluorinated surfactant sodium dodecyl sulfate (SDS). The anaerobic TCE-dechlorinating coculture was resistant to individual PFAS exposures but was inhibited by >1000× diluted AFFF. FHxSA and AmPr-FHxSA inhibited the aerobic BTEX-degrading enrichment. The anaerobic toluene-degrading enrichment was not inhibited by AFFF or individual PFASs. Increases in amino acids in the anaerobic TCE-dechlorinating coculture compared to the control indicated stress response, whereas the BTEX culture exhibited lower concentrations of all amino acids upon exposure to most surfactants (both fluorinated and nonfluorinated) compared to the control. These data suggest the main mechanisms of microbial toxicity are related to interactions with cell membrane synthesis as well as protein stress signaling.

AbstractOur research described in this paper investigated the environmental degradation of polypropylene (PP) films incorporating pro-oxidants and assessed their impact on the ecosystem. Weathering aging effects were monitored through Fourier-Transform Infrared (FTIR) analysis, revealing significant changes in carbonyl, hydroxyl and amorphous regions post-aging. The presence of pro-oxidants intensified these changes, indicating higher oxidation levels. Contact angle measurements demonstrated decreased hydrophobicity upon aging, particularly pronounced in pro-oxidant-containing films (initial contact angle: 87.79° for PP/1% Co/1% Fe, sample (F6) decreased to 79.24° after aging). Differential Scanning Calorimetric (DSC) analysis revealed decreased melting temperatures (initial Tm: 159.5 °C for F6 decreased to 148 °C after aging) and the crystallinity post-aging (initial χ: 73.25% for F6 decreased to 60.17% after aging), suggesting increased susceptibility to degradation. Thermogravimetric Analysis (TGA) showed decreased thermal stability after aging, especially in PP/pro-oxidant films; the Tonset (T5); 432.00 °C for F6, decreased to 268.00 °C after aging; where Tonset is the temperature corresponding to 5% weight loss. Biodegradation tests indicated enhanced biodegradability in the pro-oxidant-containing films, with cobalt and ferrous stearate mixtures showing the highest degradation degrees (e.g., PP/1% Co/1% Fe: ≈ 77% biodegradation after 140 days). Ecotoxicological evaluations, including microbial toxicity and plant germination and growth tests, revealed no inhibitory effects of the degradation products on soil flora or plant growth, confirming their nontoxic nature. Overall, we believe this comprehensive study provides insights into the environmental fate of PP films with pro-oxidants, highlighting their potential for accelerated degradation without adverse ecological impacts. [ABSTRACT FROM AUTHOR]

Microbial toxicity tests play an important role in various scientific and technical fields including the risk assessment of chemical compounds in the environment. There is a large battery of normalized tests available that have been standardized by ISO (International Organization for Standardization) and OECD (Organization for Economic Co-operation and Development) and which are worldwide accepted and applied. The focus of this review is to provide information on microbial toxicity tests, which are used to elucidate effects in other laboratory tests such as biodegradation tests, and for the prediction of effects in natural and technical aqueous compartments in the environment. The various standardized tests as well as not normalized methods are described and their advantages and disadvantages are discussed. In addition, the sensitivity and usefulness of such tests including a short comparison with other ecotoxicological tests is presented. Moreover, the far-reaching influence of microbial toxicity tests on biodegradation tests is also demonstrated. A new concept of the physiological potential of an inoculum (PPI) consisting of microbial toxicity tests whose results are expressed as a chemical resistance potential (CRP) and the biodegradation adaptation potential (BAP) of an inoculum is described that may be helpful to characterize inocula used for biodegradation tests. Key points: • Microbial toxicity tests standardized by ISO and OECD have large differences in sensitivity and applicability. • Standardized microbial toxicity tests in combination with biodegradability tests open a new way to characterize inocula for biodegradation tests. • Standardized microbial toxicity tests together with ecotoxicity tests can form a very effective toolbox for the characterization of toxic effects of chemicals. [ABSTRACT FROM AUTHOR]

One of the widely used microbiological methods to determine the toxicity of chemicals, catalysts, and other types of materials is the minimum inhibitory concentration (MIC) test. The present study aims to investigate the influence of composition of composite materials based on TiO2 and their particle size as well as bacterial type and shape based on the MIC values reported in the literature. The results show that among the 36 articles selected, most of the studies used Escherichia coli (E. coli) (26) and Staphylococcus aureus (S. aureus) (19) bacteria to determine MIC values. This study revealed that the MIC in values below 70 µg ml−1 for S. aureus was lower than that for E. coli bacteria (below 200 µg ml−1). Importantly, MIC value decreased from 60.6 to 7.66 µg ml−1 with decrease in the size of nanoparticles. It follows from the increased surface area for smaller-sized particles, thus increased interaction with bacteria during MIC test. [ABSTRACT FROM AUTHOR]

Purpose: The potential toxic effects due to the application of sophorolipid and the novel saponin biosurfactant extracted from the leaves of Eucalyptus camaldulensis for the purpose of bioremediating PAH-contaminated soils and sediments were studied. Methods: The phytotoxic effects of sophorolipid and eucalyptus saponin were determined based on the seed germination assays carried out using the seeds of Lactuca sativa L and compared with commonly used rhamnolipid and Tween 20 surfactants. Further, biosurfactant-induced changes in soil/sediment bacterial structure and diversity were investigated by conducting Miseq amplicon sequencing of the bacterial genes. Results: Germination indices (GI) demonstrated the non-phytotoxic effects (GI > 80%) of saponin and sophorolipid biosurfactants (100–500 mg/L), while rhamnolipid demonstrated greater phytotoxicity than Tween 20 at high concentrations (500 mg/L). Saponin-amended soil resulted in greater bacterial diversity and richness compared to controls, while sophorolipid produced the opposite effect. These significant variations were not observed in sediment samples. Incubation of biosurfactants for 20 and 40 days did not result in significant changes in bacterial diversity and structure in any of the samples. Increased abundance of some of the PAH-degrading bacteria was noted at OTU level, in the presence of saponin and sophorolipid. Saponin had less impact on native soil/sediment bacteria relative to sophorolipid based on the prevalence of the significantly shifted OTUs. Conclusion: As saponin and sophorolipid were shown to have no adverse impacts on the microbiome, and non-phytotoxic effects, their sustainable applications to remediate PAH-contaminated soils and sediments can be recommended. [ABSTRACT FROM AUTHOR]

AbstractAdvanced industrialization has caused an increase in the continuous discharge of hazardous effluents in the environment. This study evaluated the potential of the laccase synthesized by Bacillus sp. NU2 to degrade five synthetic dyes. Sawdust, wheat bran and peels of banana and tangerine were utilized as carbon sources for bacterial growth and laccase production. The produced crude enzyme was purified to homogeneity to determine its molecular weight. The kinetic activity of the purified laccase was determined using 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The toxicity of the laccase-treated dye solution was assessed on Bacillus sp. NU2 growth. The result showed optimum laccase yield from the tangerine peel medium. The purified laccase gave a specific activity of 349.94 U mg−1 and a molecular weight of 55 kDa, respectively. The purified laccase displayed a strong affinity for ABTS substrate with an enzyme activity of 31.21 U mg−1. It was optimum at 60 °C and pH 8, with catalytic efficiency (Kcat/Km) of 23.93 mmol L−1. The decolourization effects on Congo Red, Methyl Orange, Remazol Brilliant Blue R, Reactive Blue 4 and Malachite Green were 87%, 70%, 65%, 63% and 51%, respectively. The toxicity assay of laccase degraded dyes on Bacillus sp. NU2 showed a growth reduction of 36.75% (Malachite Green), 12.57% (Congo Red), 17.19% (Methyl Orange), 38.41% (Remazol Brilliant Blue R) and 28.14% (Reactive Blue 4). The laccase produced by Bacillus sp. NU2 holds a high catalytic potential for the detoxification of dye effluents in an environmental system.

The unique properties of NB, such as its nano-size effect and greater adsorption capacity, have the potential to mitigate ammonia (NH3) emission, but may also pose threats to soil life and their associated processes, which are not well understood. We studied the influence of different NB concentrations on NH3 emission, soil microbial biomass, nutrient mineralization, and corn nutrient uptake from farmyard manure (FM). Three different NB concentrations i.e., 12.5 (NB1), 25 (NB2), and 50% (NB3), alone and in a fertilizer mixture with FM, were applied to corn. NB1 alone increased microbial biomass in soil more than control, but other high NB concentrations did not influence these parameters. In fertilizer mixtures, NB2 and NB3 decreased NH3 emission by 25% and 38%, respectively, compared with FM alone. Additionally, NB3 significantly decreased microbial biomass carbon, N, and soil potassium by 34%, 36%, and 14%, respectively, compared with FM. This toxicity to soil parameters resulted in a 21% decrease in corn K uptake from FM. Hence, a high NB concentration causes toxicity to soil microbes, nutrient mineralization, and crop nutrient uptake from the FM. Therefore, this concentration-dependent toxicity of NB to soil microbes and their associated processes should be considered before endorsing NB use in agroecosystems. [ABSTRACT FROM AUTHOR]

The unique properties of NB, such as its nano-size effect and greater adsorption capacity, have the potential to mitigate ammonia (NH3) emission, but may also pose threats to soil life and their associated processes, which are not well understood. We studied the influence of different NB concentrations on NH3 emission, soil microbial biomass, nutrient mineralization, and corn nutrient uptake from farmyard manure (FM). Three different NB concentrations i.e., 12.5 (NB1), 25 (NB2), and 50% (NB3), alone and in a fertilizer mixture with FM, were applied to corn. NB1 alone increased microbial biomass in soil more than control, but other high NB concentrations did not influence these parameters. In fertilizer mixtures, NB2 and NB3 decreased NH3 emission by 25% and 38%, respectively, compared with FM alone. Additionally, NB3 significantly decreased microbial biomass carbon, N, and soil potassium by 34%, 36%, and 14%, respectively, compared with FM. This toxicity to soil parameters resulted in a 21% decrease in corn K uptake from FM. Hence, a high NB concentration causes toxicity to soil microbes, nutrient mineralization, and crop nutrient uptake from the FM. Therefore, this concentration-dependent toxicity of NB to soil microbes and their associated processes should be considered before endorsing NB use in agroecosystems.

Aryl-iodonium salts are utilized as photoacid generators (PAGs) in semiconductor photolithography and other photo-initiated manufacturing processes. Despite their utilization and suspected toxicity, the fate of these compounds within the perimeter of semiconductor fabrication plants is inadequately understood; the identification of photolithography products is still needed for a comprehensive environmental impact assessment. This study investigated the photolytic transformation of a representative iodonium PAG cation, bis-(4-tert-butyl phenyl)-iodonium, under conditions simulating industrial photolithography. Under 254-nm irradiation, bis-(4-tert-butyl phenyl)-iodonium reacted rapidly with a photolytic half-life of 39.2 s; different counter ions or solvents did not impact the degradation kinetics. At a semiconductor photolithography-relevant UV dosage of 25 mJ cm−2, 33% of bis-(4-tert-butyl phenyl)-iodonium was estimated to be transformed. Six aromatic/hydrophobic photoproducts were identified utilizing a combination of HPLC–DAD and GC–MS. Selected photoproducts such as tert-butyl benzene and tert-butyl iodobenzene had remarkably higher acute microbial toxicity toward bacterium Aliivibrio fischeri compared to bis-(4-tert-butyl phenyl)-iodonium. Octanol–water partition coefficients estimated using the Estimation Programs Interface Suite™ indicated that the photoproducts were substantially more hydrophobic than the parent compound. The results fill a critical data gap hindering the environmental impact assessment of iodonium PAGs and provide clues on potential management strategies for both iodonium compounds and their photoproducts. [ABSTRACT FROM AUTHOR]

A novel approach had been carried out to develop fungal consortium, namely, RH-2, containing two marine procured fungal isolates in order to evaluate biodegradation of recalcitrant diazo dye Congo red. The fungi were isolated from the seacoast of Diu, India. According to the ITS sequencing, the strains were identified as Penicillium oxalicum (DS-2) and Aspergillus tubingensis (DS-4). Discs of 12 mm were cut out from the edge of both the fungal isolates (DS-2 and DS-4) and inoculated in flasks consisting of potato dextrose broth with 100 mg/L Congo red for the development of fungal consortium RH-2. The degradation by the fungal consortium RH-2 was more effective than the fungal monocultures DS-2 and DS-4 with the respective degradation reaching 97.15 ± 0.15%, 68.96 ± 0.09%, and 29.96 ± 0.21% in addition of yeast extract (1% w/v) within 12 h. The influence of dextrose (1% w/v), yeast extract (1% w/v), pH 5, and salt concentration (1% w/v) enhanced the degradation potential of fungal consortium RH-2. The maximal degradation was correlated with the production of laccase (12.498 ± 0.21 U/mL) and manganese peroxidase (10.314 ± 0.25 U/mL). The catabolism of Congo red was confirmed by UV–Visible spectroscopic analysis (Congo red λ-max = 499 nm) and ATR-FTIR spectroscopic analysis. The filtrates obtained after Congo red degradation were also evaluated for microbial toxicity against bacteria (Bacillus haynesii) and phytotoxicity analysis on plant seed (Trigonella foenum) which revealed that the filtrate acquired after the treatment of Congo red by fungal consortium RH-2 was less toxic than the original dye in nature. A novel aspect is determined by the evidence of mutualistic interaction between two different fungi for the rapid decolorization and degradation of dye providing a prospective of utilizing the developed consortium RH-2 as a cost-effective approach in textile wastewater treatment for cleaner environment. [ABSTRACT FROM AUTHOR]

Advanced industrialization has caused an increase in the continuous discharge of hazardous effluents in the environment. This study evaluated the potential of the laccase synthesized by Bacillus sp. NU2 to degrade five synthetic dyes. Sawdust, wheat bran and peels of banana and tangerine were utilized as carbon sources for bacterial growth and laccase production. The produced crude enzyme was purified to homogeneity to determine its molecular weight. The kinetic activity of the purified laccase was determined using 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The toxicity of the laccase-treated dye solution was assessed on Bacillus sp. NU2 growth. The result showed optimum laccase yield from the tangerine peel medium. The purified laccase gave a specific activity of 349.94 U mg−1 and a molecular weight of 55 kDa, respectively. The purified laccase displayed a strong affinity for ABTS substrate with an enzyme activity of 31.21 U mg−1. It was optimum at 60 °C and pH 8, with catalytic efficiency (Kcat/Km) of 23.93 mmol L−1. The decolourization effects on Congo Red, Methyl Orange, Remazol Brilliant Blue R, Reactive Blue 4 and Malachite Green were 87%, 70%, 65%, 63% and 51%, respectively. The toxicity assay of laccase degraded dyes on Bacillus sp. NU2 showed a growth reduction of 36.75% (Malachite Green), 12.57% (Congo Red), 17.19% (Methyl Orange), 38.41% (Remazol Brilliant Blue R) and 28.14% (Reactive Blue 4). The laccase produced by Bacillus sp. NU2 holds a high catalytic potential for the detoxification of dye effluents in an environmental system. [ABSTRACT FROM AUTHOR]

Microbial toxicity of test substances in tetrazolium assay is often quantified while referring to their IC50 values. However, the implication of such an estimate is very limited and can differ across studies depending on prevailing test conditions. In this work, a factorial design-based end-point microbial toxicity assay was performed, which suggests a significant interaction (P= 0.041) between inoculum and tetrazolium dose on formazan production. Subsequently, a dynamic model framework was utilized to capture the nonlinearities in biomass, substrate, formazan profiles and to project the toxicant inhibition parameter as a robust alternative to IC50 value. Microbial growth, glucose uptake and formazan production in the presence or absence of toxicant (Cu2+) from designed batch experiments were used for sequential estimation of model parameters, and their confidence intervals. A logistic growth model with multiplicative inhibition terms for formazan content and toxicant concentration fits the experimental data reasonably well (R2>0.96). Dynamic relative sensitivity analysis revealed that both microbial growth and formazan production profiles were sensitive to toxicant inhibition parameter. The modelling framework not only provides a better insight into the underlying toxic effect but also offers a stable toxicity index for the test substances that can be extended to design a versatile, robust in vitro assay system. [ABSTRACT FROM AUTHOR]

Abstract Seaweed Sargassum wightii is one of the most important marine resources as they have biological activity. Numerous researchers have reported on brilliant green dye decolourization using various seaweed. Despite its impact on after treatment, little information is available on the effect of seaweed-treated dye toxicity against plants and microorganisms. The present investigation was carried out to assess the microbial toxicity of S. wightii-treated and untreated dye using various microorganisms and cytotoxicity effect on Allium cepa L. In this study, untreated dye which has substantial amount of the colour in it exhibited significant toxic effect against major gram-positive and gram-negative bacteria. The clear zone of inhibition exhibited by the untreated dye around bacterial and fungal colonies reflects its extent of microbial toxicity and infers that the untreated dye has antibacterial and antifungal activity. No inhibition zones were observed with treated dye when compared with the untreated dye. Consequently, treated dye does not exhibit microbial toxicity due to the complete absence of the dye in it. Cytotoxicity study on A. cepa grown in untreated dye solution showed decrease in root growth, increase in the mitotic index and chromosomal damage, whereas A. cepa bulbs grown in seaweed-treated dye showed betterment in root growth, increase in the mitotic index and decrease in chromosomal damage. Results of the cytotoxicity study indicated the untreated dye solution exerts toxic effect on A. cepa, whereas treated dye solution did not pose any toxic effect. This indirectly proves the efficiency of marine algae in complete removal of the dye from the present study. Thus, worldwide awareness of dye removal from aqueous solution and its management could be provoked.

Fungi are capable of treating various synthetic dye effluents. Previously, we isolated seven strains of fungi from contaminated batik dye effluent at Banyumas, Central Java. The aims of this study were to screen the ability of these fungi to decolorize batik dye effluents containing Indigosol Blue-04B and to investigate the phytotoxicity effects of biodegraded effluent on the germination of corn seeds Zea mays L. and green bean seeds Vigna radiate (L.) Wilczek. In addition, the decolorized effluents were tested for toxic effect on the agriculturally important gram-positive and gram-negative soil bacteria Bacillus cereus and Azotobacter sp., Staphylococcus aureus and Escherichia coli, respectively. Study of decolorization showed that fungi were able to decolorize Indigosol Blue-04B batik dye effluents by 21.04% to 99.89% at room temperature after three days of incubation. The assay of phytotoxicity showed that both plumule and radicle length of Z. mays and V. radiata grown on the decolorized effluent was longer than on untreated effluent. The percentage of Z. mays and V. radiata seed germination in decolorized effluent was higher than in untreated effluent. There was no inhibition zone found around the decolorized effluent samples after incubating the bacteria for 48 hours. Aspergillus sp. 3 was the most effective for degradation and could be used for batik effluent mycoremediation processes.

Despite the widespread utilization of onium salts as photoacid generators (PAGs) in semiconductor photolithography, their environmental, health, and safety (EHS) properties remain poorly understood. The present work reports the bioconcentration potential of five representative onium species (four sulfonium and one iodonium compound) by determining the octanol–water partition coefficient (POW) and lipid membrane affinity coefficient (KMA); microbial toxicity was evaluated using the bioluminescent bacterium Aliivibrio fischeri (Microtox bioassay). Four of the oniums exhibited varying degrees of hydrophobic (lipophilic) partitioning (log POW: 0.08–4.12; KMA: 1.70–5.62). A strong positive linear correlation was observed between log POW and KMA (KMA = log POW + 1.76, R2 = 0.99). The bioconcentration factors (log BCF) estimated from POW and KMA for the four oniums ranged from 0.13 to 3.67 L kg−1. Bis-(4-tert-butyl phenyl)-iodonium and triphenylsulfonium had 50% inhibitory concentrations (IC50) of 4.8 and 84.6 μM, whereas the IC50 values of the other three oniums were not determined because these values were higher than their aqueous solubility. Given the increased regulatory scrutiny regarding the use and potential health impacts from onium PAGs, this study fulfills critical knowledge gaps concerning the EHS properties of PAG oniums, enabling more comprehensive evaluation of their environmental impacts and potential risk management strategies. [ABSTRACT FROM AUTHOR]

Standard ready biodegradability tests are conducted at unrealistically high test concentration and therefore cannot properly evaluate toxic substances to microorganisms. The present study evaluated the effects of four adsorbent carriers in modified ready biodegradability tests of four quaternary ammonium salts (QASs) demonstrating microbial toxicity according to the Organization for Economic Co-operation and Development Test Guideline 301F and cautions for using carriers were found. In the tests with silica gel, the concentration of all QASs in the test solutions decreased due to adsorption. The percentages of biodegradation of octadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, and benzyldimethyloctadecylammonium chloride, which have a linear alkyl chain, were 89.9%, 80.6%, and 70.1% on day 28, respectively; benzethonium chloride, with a branched alkyl chain, did not undergo biodegradation. In the tests with activated carbon, although the concentrations of QASs greatly decreased, no QASs underwent biodegradation. In the tests with sea sand or quartz sand, QASs were not adsorbed on the carriers and were not biodegraded. Using an adsorbent carrier for toxic substances will increase biodegradation, but it has no effect on highly persistent substances with specific chemical structures, e.g., branched carbons, which is very important because ready biodegradability is not overestimated. Carriers having moderate adsorbability should be selected. [ABSTRACT FROM AUTHOR]

• Polystyrene nanoplastics have noticeable inhibitory effect on biodegradation system. • Smaller size ones (20 nm) pose remarkably more damage than larger ones (100 nm). • Both sizes of PS-NPs aggravate bacteria oxidative stress, decrease microbial diversity. • PS-NPs alter ecological niche of different microbial species and microbial network. • Functional species and metabolic pathway respond differentially to PS100 and PS20. Nanoplastics (NPs), as a type of newly emerging pollutant, are ubiquitous in various environmental systems, one of which is coexistence with organic pollutants in wastewater, potentially influencing the pollutants' biodegradation. A knowledge gap exists regarding the influence of microbial consortium and NPs interactions on biodegradation efficiency. In this work, a 2,4-dichlorophenol (DCP) biodegradation experiment with presence of polystyrene nanoplastics (PS-NPs) with particle sizes of 100 nm (PS 100) or 20 nm (PS 20) was conducted to verify that PS-NPs had noticeable inhibitory effect on DCP biodegradation in a size-dependent manner. PS 100 at 10 mg/L and 100 mg/L both prolonged the microbial stagnation compared to the control without PS-NPs; PS 20 exacerbated greater, with PS 20 at 100 mg/L causing a noticeable 6-day lag before the start-up of rapid DCP reduction. The ROS level increased to 1.4-fold and 1.8-fold under PS 100 and PS 20 exposure, respectively, while the elevated LDH under PS 20 exposure indicated the mechanical damage to cell membrane by smaller NPs. PS-NPs exposure also resulted in a decrease in microbial diversity and altered the niches of microbial species, e.g., they decreased the abundance of some functional bacteria such as Brevundimonas and Comamonas , while facilitated some minor members to obtain more proliferation. A microbial network with higher complexity and less competition was induced to mediate PS-NPs stress. Functional metabolism responded differentially to PS 100 and PS 20 exposure. Specifically, PS 100 downregulated amino acid metabolism, while PS 20 stimulated certain pathways in response to more severe oxidative stress. Our findings give insights into PS-NPs environmental effects concerning microflora and biological degradation. [Display omitted] [ABSTRACT FROM AUTHOR]

One of the widely used microbiological methods to determine the toxicity of chemicals, catalysts, and other types of materials is the minimum inhibitory concentration (MIC) test. The present study aims to investigate the influence of composition of composite materials based on TiO 2 and their particle size as well as bacterial type and shape based on the MIC values reported in the literature. The results show that among the 36 articles selected, most of the studies used Escherichia coli ( E. coli ) (26) and Staphylococcus aureus ( S. aureus ) (19) bacteria to determine MIC values. This study revealed that the MIC in values below 70 µg ml -1 for S. aureus was lower than that for E. coli bacteria (below 200 µg ml -1 ). Importantly, MIC value decreased from 60.6 to 7.66 µg ml -1 with decrease in the size of nanoparticles. It follows from the increased surface area for smaller-sized particles, thus increased interaction with bacteria during MIC test.

Ionic liquids (ILs) based surfactants have been emerged as attractive alternatives to the conventional surfactants owing to their tailor-made and eco-friendly properties. Therefore, present study described the synthesis of nine new fatty amino acids based IL surfactants utilizing lauroyl sarcosinate anion and pyrrolidinium, imidazolium, pyridinium, piperidinium, morpholinium and cholinium cations for the first time. The synthesized surface active lauroyl sarcosinate ionic liquids (SALSILs) were characterized by 1H NMR, 13C NMR and TGA. Next, the surface tension and critical micellar concentrations were determined and compared with the surface properties of ILs based surfactants. Further, the toxicity and biodegradability of the synthesized SALSIILs were evaluated to confirm their safe and efficient process applications. The studies revealed that three out of nine synthesized SALSILs containing pyridinium cation have showed strong activity towards the tested microbial growth. The remaining six SALSILs met the biocompatible measures demonstrating moderate to low activity depends on the tested microbes. The alicyclic SALSILs containing morpholinium and piperidinium cations have demonstrated 100% biodegradation after 28 days of the test period. Overall, it is believed that the synthesized SALSILs could effectively replace the conventional surfactants in a wide variety of applications. • Successfully synthesized nine different SALSILs for the first time. • Toxicity and biodegradability of all synthesized SALSILs were evaluated in detail. • SALSILs with morpholinium and piperidinium cations showed 100% biodegradation. • Synthesized SALSILs could be utilized in food, cosmetic and oil & gas industries. [ABSTRACT FROM AUTHOR]

Abstract Mangiferin, a bioactive compound with numerous therapeutic properties was extracted from Curcuma amada. To solve the bioavailability issues of mangiferin, it was encapsulated in β-lactoglobulin (β-LG), by desolvation method and reduced to a nano size. From the Dynamic Light Scattering (DLS) data, average particle size and zeta potential of the nanoparticle was 89 ± 10 nm and −30.0 ± 0.2 mV respectively. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) results illustrated the spherical and uniform size (approximately 70 nm) of the nanoparticles. The release kinetics of mangiferin by simulated gastrointestinal (GI) studies demonstrated more resistance of nanoparticles towards pepsin digestion in comparison with pancreatin digestion. Release of mangiferin observed in colon fluid was 80%. In vitro release kinetics, by Kopcha model, predicted that the mangiferin release from the nanoparticles follows a non-Fickian process. The Baker–Lonsdale model further predicted the spherical shape of the nanoparticles. The nanoparticles can be stored for 30 days at 4 °C retaining its activity. DPPH assay proved that nanoencapsulation of mangiferin retained the antioxidant property. Nanoparticles demonstrated anti-microbial activity against Staphylococcus aureus and Escherichia coli. No toxicity was observed towards the useful probiotic strain of gastrointestinal tract. The study could establish that the mangiferin/β-lactoglobulin nanoparticles might be a promising candidate for oral delivery. Highlights • Mangiferin was encapsulated in β-Lactoglobulin to improve its bio-availability. • Nanoparticles are spherical and uniform in size. • Maximum mangiferin release was observed in simulated colon fluid. • Nanoparticles can be stored for 30 days. • The antioxidant properties of mangiferin was retained by nanoencapsulation. [ABSTRACT FROM AUTHOR]

Nuclear polyhedrosis virus (NPV) and Bacillus thuringiensis (Bt) are potential biological pest controller which can regulate an extensive range of bollworms larvae in both Agricultural and Horticultural crops. Spodoptera litura is a commercial pest of diverse field crops comprising cauliflower (Brassica oleracea var. botrytis). Current inspections were carried out to determine their impact on larval mortality, pupal and adult emergence by exposing three field strains of S. litura (Faisalabad, Chiniot and Sargodha), under laboratory conditions. Both NPV and Bt were applied using diet incorporation method. Two concentrations of a NPV based formulation (Somestar): 1x107 and 1x108 POB/ml, and three concentrations of a Bt based formulation (Dipel): viz., 0.1, 0.3 and 0.5 µg/g, were applied alone and in different combinations against 2nd and 4th instar larvae of S. litura. The highest mortality of larvae was recorded after 7 days of application when both insect pathogens were used in combination (SpltNPV 1×108 POB/ml + Bt 0.1 µg/g) i.e. 85.25, 79.31 and 92.11% mortality (in case of 2nd instar larvae) and 70.42, 63.64 and 80.88% (in case 4th instar larvae) of Faisalabad, Chiniot and Sargodha's population of S. litura, respectively. This study could be helpful to use NPV and Bt in intensive pest management under field conditions to control S. litura on cauliflower. [ABSTRACT FROM AUTHOR]

The prediction of chemical mixture toxicity is a major concern regarding unintentional mixture of pesticides from agricultural lands treated with various such compounds. We focused our work on a mixture of three herbicides commonly applied on maize crops within a fortnight, namely mesotrione (β-triketone), nicosulfuron (sulfonylurea) and S-metolachlor (chloroacetanilide). The metabolic pathways of mesotrione and nicosulfuron were qualitatively and quantitatively determined with a bacterial strain ( Bacillus megaterium Mes11). This strain was isolated from an agricultural soil and able to biotransform both these herbicides. Although these pathways were unaffected in the case of binary or ternary herbicide mixtures, kinetics of nicosulfuron disappearance and also of mesotrione and nicosulfuron metabolite formation was strongly modulated. The toxicity of the parent compounds and metabolites was evaluated for individual compounds and mixtures with the standardized Microtox® test. Synergistic interactions were evidenced for all the parent compound mixtures. Synergistic, antagonistic or additive toxicity was obtained depending on the metabolite mixture. Overall, these results emphasize the need to take into account the active ingredient and metabolites all together for the determination of environmental fate and toxicity of pesticide mixtures. [ABSTRACT FROM AUTHOR]

The effect of humic substances (HS) and their different fractions (humic acids (HA) and hymatomelanic acids (HMA)) on the toxicity of zinc and lead to different strains of bacteria was studied. All tested bacteria demonstrated a lower resistance to zinc than lead showing minimum inhibitory concentrations of 0.1 − 0.3 mM and 0.3–0.5 mM, respectively. The highest resistance to lead was characteristic of Pseudomonas chlororaphis PCL1391 and Rhodococcus RS67, while Pseudomonas chlororaphis PCL1391 showed the greatest resistance to zinc. The combined fractions of HS and HA alone reduced zinc toxicity at all added concentrations of the organic substances (50 – 200 mg L −1 ) to all microorganisms, while hymatomelanic acids reduced zinc toxicity to Pseudomonas chlororaphis PCL1391 at 200 mg L −1 organic concentration only. The HS fractions imparted similar effects on lead toxicity also. This study demonstrated that heavy metal toxicity to bacteria could be reduced through complexation with HS and their fractions. This was particularly true when the metal-organic complexes held a high stability, and low solubility and bioavailability. [ABSTRACT FROM AUTHOR]

The insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO) was recently approved by the U.S. Army to replace cyclotrimethylene trinitramine (RDX) in conventional explosives. As its use becomes widespread, concern about the potential toxicity of NTO increases. NTO can undergo microbial reduction to 3-amino-1,2,4-triazol-5-one (ATO), which is recalcitrant in waterlogged soils. In this study, the acute toxicity of NTO and ATO towards various organisms, including microorganisms ( i.e. , methanogenic archaea, aerobic heterotrophs, and Aliivibrio fischeri (Microtox assay)), the microcrustacean Daphnia magna (ATO only), and zebrafish embryos ( Danio rerio ), was assessed. NTO was notably more inhibitory to methanogens than ATO (IC 50 = 1.2 mM, > 62.8 mM, respectively). NTO and ATO did not cause noteworthy inhibition on aerobic heterotrophs even at the highest concentrations tested (32.0 mM). High concentrations of both NTO and ATO were required to inhibit A. fischeri (IC 20 = 19.2, 22.4 mM, respectively). D. magna was sensitive to ATO (LC 50 = 0.27 mM). Exposure of zebrafish embryos to NTO or ATO (750 μM) did not cause lethal or developmental effects (22 endpoints tested). However, both compounds led to swimming behavior abnormalities at low concentrations (7.5 μM). The results indicate that the reductive biotransformation of NTO could enhance or lower its toxicity according to the target organism. [ABSTRACT FROM AUTHOR]

Water pollution is one of the major concerns over long-term sustainability of the environment. Effective and efficient treatment of polluted wastewater is still a serious challenge for global researchers. In the last 2-3 decades, due to the incessant emergence of micropollutants in surface and ground water bodies, several endeavors have been made to resolve the water pollution issues either through chemical, physical and biological degradation processes or through removal/separation processes using different adsorbents and membranes. It has been found that most of the studies are mainly limited to single or binary pollutant analysis in a pure water matrix. Therefore, in this novel investigation, a mixture of five different pollutants has been studied for UV/TiO-based photocatalytic degradation. In the present study, a commercially available TiO, an antibiotic, i.e. Ciprofloxacin and four different synthetic dyes, i.e. Rhodamine B, Methylene Blue, Methyl Orange and Amaranth have been used as a photocatalyst, a pharmaceutical and various industrial dyes, respectively, in a batch photocatalytic reactor system with a stirrer. It is important to note that the commercial TiO photocatalyst has also been characterized with the help of several characterization techniques. The present study is mainly focused on the degradation of different micropollutants present in the simulated wastewater matrix and their individual degradation kinetics. It is interesting to observe that MB and RhB have shown the maximum degradation followed by CIP (96.21, 96.15 and 89.62%, respectively). In addition, a microbiological assay has also been performed to check the toxicity variation in the degraded products. It is quite interesting to observe that the simulated wastewater matrix has completely lost its microbial toxicity within 120 min of UV/TiO-based photocatalytic treatment. Finally, total organic carbon evaluations of various treated samples have also been performed and the obtained results substantiate the theory of assimilable organic carbon. [ABSTRACT FROM AUTHOR]

Surfactant Modified Zeolite (SMZ) represents a versatile, cost-effective permeable reactive material, capable of treating multiple classes of contaminants. The potential for HDTMA-Br, a cationic surfactant commonly used to modify zeolite, to desorb from the zeolite surface has been identified as a potential issue for the ongoing use of SMZ in water remediation contexts. This paper investigates the toxicity of HDTMA-Br towards enteric virus surrogates, F-RNA bacteriophage MS2 and E. coli , Bacillus subtilis , and soil microflora. The concentration of surfactant desorbing from SMZ was quantified through a bioassay using E. coli . Results showed HDTMA-Br concentrations of ≥10 −5 M were toxic to MS2, ≥10 −4 M were toxic to E. coli and ≥10 −6 M were toxic to B. subtilis. No toxic relationship was established between HDTMA-Br and soil microflora. Desorption of ≥10 −4 M of HDTMA-Br was shown for the two SMZ samples under the mixing conditions used. Effects of this surfactant on total soil microflora were ambiguous since no toxic relationship could be established, however, HDTMA-Br, at concentrations desorbing from SMZ, were shown to impact the soil bacterium B. subtilis . Further research is required to determine the effect of this surfactant on microbial populations and species diversity in soils. [ABSTRACT FROM AUTHOR]

III-V materials such as indium arsenide (InAs) and gallium arsenide (GaAs) are increasingly used in electronic and photovoltaic devices. The extensive application of these materials may lead to release of III-V ionic species during semiconductor manufacturing or disposal of decommissioned devices into the environment. Although arsenic is recognized as an important contaminant due to its high toxicity, there is a lack of information about the toxic effects of indium and gallium ions. In this study, acute toxicity of As(III), As(V), In(III) and Ga(III) species was evaluated using two microbial assays testing for methanogenic activity and O 2 uptake, as well as two bioassays targeting aquatic organisms, including the marine bacterium Aliivibrio fischeri (bioluminescence inhibition) and the crustacean Daphnia magna (mortality). The most noteworthy finding was that the toxicity is mostly impacted by the element tested. Secondarily, the toxicity of these species also depended on the bioassay target. In(III) and Ga(III) were not or only mildly toxic in the experiments. D. magna was the most sensitive organism for In(III) and Ga(III) with 50% lethal concentrations of 0.5 and 3.4 mM, respectively. On the other hand, As(III) and As(V) caused clear inhibitory effects, particularly in the methanogenic toxicity bioassay. The 50% inhibitory concentrations of both arsenic species towards methanogens were about 0.02 mM, which is lower than the regulated maximum allowable daily effluent discharge concentration (2.09 mg/L or 0.03 mM) for facilities manufacturing electronic components in the US. Overall, the results indicate that the ecotoxicity of In(III) and Ga(III) is much lower than that of the As species tested. This finding is important in filling the knowledge gap regarding the ecotoxicology of In and Ga. [ABSTRACT FROM AUTHOR]

In order to explore the toxicity of hebicides on soil microorganisms, the nitrogen transformation of microorganisms in fluvo-aquic soil and the respiration intensity of microorganisms in krasnozem, brown soil and fluvo-aquic soil were determined after exposure to sulfometuron methyl and clodinafop-propargyl, respectively. The soils were treated with these herbicides at the recommended field concentration (RFC), 10 and 100-fold of RFC and then incubated for 15 days. In terms of sulfometuron methyl, the inhibition of respiration was abserved in the exposed brown soil, whereas soil respiration intensity was significantly increased in fluvo-aquic soil. In krasnozem, soil respiration was inhibited after the exposure to sulfometuron methyl in 10 fold application rate treatment, but it was stimulated in the other two treatments. With regards of clodinafop-propargyl, the results indicated that respiration were inhibited in krasnozem and brown soils, but it was stimulated in fluvo-aquic soil. Regarding to nitrogen transformation, sulfometuron methyl significantly increased the NO3--N contents of the fluvo-aquic soil after the exposure to the recommended field concentration (RFC) and 5-fold of RFC for 7, 14, 28, 42, 56 and 70 d, respectively. The NO3--N contents was significantly increased 28 d after the exposure to clodinafop-propargy. However, no significant change between the control and the treatment group was observed 0, 7, 14 and 42d after the exposure. In summary, sulfometuron methyl and clodinafop-propargyl showed low toxicity to soil respiration intensity in the three soils, and no longterm effects on nitrogen transformation were observed in the fluvo-aquic soil. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing has advanced the development of shale gas extraction, while inadvertent spills of flowback water may pose a risk to the surrounding environment due to its high salt content, metals/metalloids (As, Se, Fe and Sr), and organic additives. This study investigated the potential impact of flowback water on four representative soils from shale gas regions in Northeast China using synthetic flowback solutions. The compositions of the solutions were representative of flowback water arising at different stages after fracturing well establishment. The effects of solution composition of flowback water on soil ecosystem were assessed in terms of metal mobility and bioaccessibility, as well as biological endpoints using Microtox bioassay ( Vibrio fischeri ) and enzyme activity tests. After one-month artificial aging of the soils with various flowback solutions, the mobility and bioaccessibility of As(V) and Se(VI) decreased as the ionic strength of the flowback solutions increased. The results inferred a stronger binding affinity of As(V) and Se(VI) with the soils. Nevertheless, the soil toxicity to Vibrio fischeri only presented a moderate increase after aging, while dehydrogenase and phosphomonoesterase activities were significantly suppressed with increasing ionic strength of flowback solutions. On the contrary, polyacrylamide in the flowback solutions led to higher dehydrogenase activity. These results indicated that soil enzyme activities were sensitive to the composition of flowback solutions. A preliminary human health risk assessment related to As(V) suggested a low level of cancer risk through exposure via ingestion, while holistic assessment of environmental implications is required. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) has emerged as a promising technology for diverting the organic waste from the landfills along with the production of clean energy. AD is a microbial-driven biochemical process wherein the plethora of microbial communities participate in converting the putrescible organic matter into biogas. Nevertheless, the AD process is susceptible to the external environmental factors such as presence of physical (microplastics) and chemical (antibiotics, pesticides) pollutants. The microplastics (MPs) pollution has received recent attention due to the increasing plastic pollution in terrestrial ecosystems. This review was aimed for holistic assessment of impact of MPs pollution on AD process to develop efficient treatment technology. First, the possible pathways of MPs entry into the AD systems were critically evaluated. Further, the recent literature on the experimental studies pertaining to the impact of different types of MPs at different concentrations on the AD process was reviewed. In addition, several mechanisms such as direct exposure of MPs on the microbial cells, indirect impact of MPs through the leaching of toxic chemicals and reactive oxygen species (ROS) formation on AD process were elucidated. Besides, the risk possessed by the increase of antibiotic resistance genes (ARGs) after the AD process due to the MPs stress on microbial communities were discussed. Overall, this review deciphered the severity of MPs pollution on AD process at different levels. [Display omitted] • Microplastics influence the biochemical pathways of anaerobic digestion process. • Microplastics directly interact with microbial cells and disrupt the cell walls. • Leaching & reactive oxygen species formation are the indirect inhibitory pathways. • Microplastics exposure increases the abundances of antibiotic resistance genes. [ABSTRACT FROM AUTHOR]

The applicability of herbicidal ionic liquids (HILs) as an alternative form of herbicides is currently evaluated. Yet, the available research is lacking information on the behaviour of herbicidal ionic liquids upon addition to the environment, i.e. , if cations and anions act as separate moieties or remain an ionic salt. Hence, we tested degradation of five HILs with the glyphosate anion, their bioavailability in soil, toxicity towards microorganisms, impact on the biodiversity and the abundance of phnJ and soxA genes. The cations were proven to be slightly or moderately toxic. The properties of cations determined the properties of the whole formulation, which might suggest that cations and anion act as the independent mixture of ions. The mineralisation efficiencies were in the range of 15–53%; however, in the case of cations (except non-toxic choline), only 13–20% were bioavailable for degradation. The hydrophobic cations were proven to be highly sorbed, while the anion was readily available for microbial degradation regardless of its counterion. The approach to enrich test samples with isolated microorganisms specialised in glyphosate degradation resulted in higher degradation efficiencies, yet not high enough to mitigate the negative impact of cations. In addition, increased activity of enzymes participating in glyphosate degradation was observed. In the view of obtained results, the use of cationic surfactants in HILs structure is not recommended, as sorption was shown to be determining factor in HILs degradation efficiency. Moreover, obtained results indicate that corresponding ions in HILs might act as separate moieties in the environment. [Display omitted] • Cations and anions in HILs act as separate moieties in soils. • Quaternary ammonium cations in HILs are toxic and tend to sorb in soils. • Bioaugmentation approach was insufficient to minimise cation's impact. • Toxicity and biodegradation of HILs are reflecting cation's properties. [ABSTRACT FROM AUTHOR]

This work investigated the microbial toxicity of soluble species that can potentially be leached from the II-VI semiconductor materials, cadmium telluride and cadmium selenide. The soluble ions tested included: cadmium, selenite, selenate, tellurite, and tellurate. Their toxicity towards the acetoclastic and hydrogen-consuming trophic groups in a methanogenic consortium as well as towards a bioluminescent marine bacterium, Aliivibrio fischeri (Microtox ® test), was assessed. The acetoclastic methanogenic activity was the most affected as evidenced by the low 50% inhibiting concentrations (IC 50 ) values obtained of 8.6 mg L −1 for both cadmium and tellurite, 10.2 mg L −1 for tellurate, and 24.1 mg L −1 for selenite. Both tellurium oxyanions caused a strong inhibition of acetoclastic methanogenesis at low concentrations, each additional increment in concentration provided progressively less inhibition increase. In the case of the hydrogenotrophic methanogenesis, cadmium followed by selenite caused the greatest inhibition with IC 50 values of 2.9 and 18.0 mg L −1 , respectively. Tellurite caused a moderate effect as evidenced by a 36.8% inhibition of the methanogenic activity at the highest concentration tested, and a very mild effect of tellurate was observed. Microtox ® analyses showed a noteworthy inhibition of cadmium, selenite, and tellurite with 50% loss in bioluminescence after 30 min of exposure of 5.5, 171.1, and 458.6 mg L −1 , respectively. These results suggest that the leaching of cadmium, tellurium and selenium ions from semiconductor materials can potentially cause microbial toxicity. [ABSTRACT FROM AUTHOR]

The toxicity of water-receiving bodies, the effluent and other treatment stages in wastewater treatment plants has recently been of interest to the public due to the lack of a regulated toxicity-based index for wastewater discharge in China. This study aimed to evaluate the conventional pollution parameters and toxicities of wastewaters collected at different treatment stages from a pharmaceutical industrial park wastewater treatment plant through dehydrogenase activity (DHA) and bioluminescent bacteria ( Vibrio qinghaiensis ) tests. The results of an analysis of conventional parameters indicated that the total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH 3 N), and total phosphorus (TP) were largely removed after various treatments. However, the TN, NH 3 N and COD still exceeded the regulated standards. The tested pharmaceutical park effluents were mainly polluted with organic pollutants and nitrogenous. The toxicity test results indicated that the toxicities could be markedly reduced after treatment, with the toxicities of two out of the six effluent samples at different treatment stages being greater than the influent toxicity. Spearman’s rank correlation coefficients indicated a significantly positive correlation between the toxicity values obtained using the DHA and Vibrio qinghaiensis tests. Compared with the DHA measurement, the Vibrio qinghaiensis test was faster and more sensitive. Meanwhile, the toxicity indicators were significantly and positively correlated with the TSS, TN, TP and COD concentrations. These results may aid the understanding of the toxicity of pharmaceutical industrial park wastewaters and toxicity removal using the treatment techniques that are currently utilized in China. [ABSTRACT FROM AUTHOR]

Micellar draw solutions containing either sodium dodecyl sulphate (SDS), tetraethyl ammonium bromide (TEAB), 1-Octane sulphonic acid sodium salt (1-OSA) or trimethyloctyl ammonium bromide (TMOAB) were tested in the FOMBR system. After 48 h, reverse transported draw solute concentrations with 1 M draw solution concentrations for NaCl, SDS, TEAB, TMOAB and 1-OSA reached 3.22 mg/l (55 μM), 0.012 mg/l (0.04 μM), 0.067 mg/l (0.32 μM), 0.057 mg/l (0.23 μM) and 0.062 mg/l (0.29 μM), respectively. Thus, reverse transport of surfactant solute was minimal. The toxicity of each draw solution was tested using Pseudomonas aeruginosa specie and mixed (activated) sludge. The percentage growth for P. aeruginosa at the highest tested draw solute concentration of 0.05 M was 60% for SDS and 49% for TEAB, while the other surfactants proved to be more toxic. Similar to bacterial growth, the TOC reduction was higher for P. aeruginosa when compared to the mixed sludge consortium. For membrane cleaning, 0.0005 M EDTA with 0.125 g/l NaOH (a pH of 11.6) for 0.5 h was found to be an effective cleaning strategy, along with prior- and post-cleaning of the membrane using DI water. Reuse of the regenerated draw solutes indicated that the SDS flux returned close to the original flux, while the TEAB flux reached 50% of the original. Overall, SDS and TEAB are recommended for future investigation, because of minimal reverse solute transport, low in-situ microbial toxicity, good flux recovery after membrane cleaning, and effective draw solute regeneration. [ABSTRACT FROM AUTHOR]

2,4-Dinitroanisole (DNAN) is an emerging insensitive munitions compound. It undergoes rapid (bio)transformation in soils and anaerobic sludge. The primary transformation pathway catalyzed by a combination of biotic and abiotic factors is nitrogroup reduction followed by coupling of reactive intermediates to form azo-dimers. Additional pathways include N -acetylation and O -demethoxylation. Toxicity due to (bio)transformation products of DNAN has received little attention. In this study, the toxicity of DNAN (bio)transformation monomer products and azo-dimer and trimer surrogates to acetoclastic methanogens and the marine bioluminescent bacterium, Allivibrio fischeri , were evaluated. Methanogens were severely inhibited by 3-nitro-4-methoxyaniline (MENA), with a 50%-inhibiting concentration (IC 50 ) of 25 μM, which is more toxic than DNAN with the same assay, but posed a lower toxicity to Allivibrio fischeri (IC 50 = 219 μM). On the other hand, N -(5-amino-2-methoxyphenyl) acetamide (Ac-DAAN) was the least inhibitory test-compound for both microbial targets. Azo-dimer and trimer surrogates were very highly toxic to both microbial systems, with a toxicity similar or stronger than that of DNAN. A semi-quantitative LC-QTOF-MS method was employed to determine product mixture profiles at different stages of biotransformation, and compared with the microbial toxicity of the product-mixtures formed. Methanogenic toxicity increased due to putative reactive nitroso-intermediates as DNAN was reduced. However, the inhibition later attenuated as dimers became the predominant products in the mixtures. In contrast, A. fischeri tolerated the initial biotransformation products but were highly inhibited by the predominant azo-dimer products formed at longer incubation times, suggesting these ultimate products are more toxic than DNAN. [ABSTRACT FROM AUTHOR]

N-methyl- p -nitroaniline (MNA) is an ingredient of insensitive munitions (IM) compounds that serves as a plasticizer and helps reduce unwanted detonations. As its use becomes widespread, MNA waste streams will be generated, necessitating viable treatment options. We studied MNA biodegradation and its inhibition potential to a representative anaerobic microbial population in wastewater treatment, methanogens. Anaerobic biodegradation and toxicity assays were performed and an up-flow anaerobic sludge blanket reactor (UASB) was operated to test continuous degradation of MNA. MNA was transformed almost stoichiometrically to N-methyl- p -phenylenediamine (MPD). MPD was not mineralized; however, it was readily autoxidized and polymerized extensively upon aeration at pH = 9. In the UASB reactor, MNA was fully degraded up to a loading rate of 297.5 μM MNA d −1 . Regarding toxicity, MNA was very inhibitory to acetoclastic methanogens (IC 50 = 103 μM) whereas MPD was much less toxic, causing only 13.9% inhibition at the highest concentration tested (1025 μM). The results taken as a whole indicate that anaerobic sludge can transform MNA to MPD continuously, and that the transformation decreases the cytotoxicity of the parent pollutant. MPD can be removed through extensive polymerization. These insights could help define efficient treatment options for waste streams polluted with MNA. [ABSTRACT FROM AUTHOR]

In Japan, understanding the environmental persistence of chemicals is very important for risk assessment, and ready biodegradability tests are mainly conducted according to the Organisation for Economic Co-operation and Development test guideline 301C. However, the highest test concentration specified in test guideline 301C, 100 mg/L, may cause microbial toxicity and incomplete biodegradation. The authors performed test guideline 301C tests at test concentrations of 30 mg/L for 13 substances that were readily biodegradable in ready biodegradability tests but not in test guideline 301C tests. Of the 5 substances with potential to cause microbial toxicity at 100 mg/L, the percentage of biodegradation of sodium dimethyldithiocarbamate, 4-chloro-3-cresol (CC), thymol (THY), and p-tert-butyl-α-methylbenzenepropionaldehyde measured by biochemical oxygen demand (BOD) increased in the test guideline 301C test at 30 mg/L, suggesting a reduction in toxicity effects. Furthermore, CC and THY met the criteria for ready biodegradability, which are more than 60% of biodegradation by BOD and a 10-d window. Of the 8 substances with a low potential for causing microbial toxicity at 100 mg/L, the percentage of biodegradation of only 2-(diethylamino)ethanol increased in the test guideline 301C test at 30 mg/L. Employing a lower test concentration in the standard test guideline 301C test will contribute to improvement of consistency between results of a test guideline 301C test and other ready biodegradability tests. [ABSTRACT FROM AUTHOR]

Lead (Pb) and decabromodiphenyl ether (BDE209) are the main pollutants at electronic waste (e-waste) recycling sites (EWRSs), and their potential toxic effects on soil organisms have received extensive attention. However, the impact on soil microorganisms of joint exposure to the two chemicals remains almost unknown. Therefore, indoor incubation tests were performed to explore the adverse impacts of Pb and BDE209 on soil microbial activities and chemical transformation for the first time. The results have demonstrated that BDE209 was barely degraded in all treated groups, indicating that the presence of Pb hardly affected BDE209 dissipation. The fractions analysis according to Tessier suggested that Pb gradually transformed towards more stable fractions in the slightly alkaline soil, thus reducing the bioavailability of Pb. Additionally, increased Pb doses caused significantly higher bioavailability ( p < 0.05), and the same trend was clearly observed after simultaneous exposure to BDE209. Generally, single Pb or BDE209 exposure markedly inhibited ( p < 0.05 or 0.01) soil microbial biomass C ( C), while soil basal respiration (SBR) indicated the opposite response trend (inhibition or stimulation for BDE209 or Pb alone, respectively). Compared to the controls, Pb dramatically ( p < 0.01) facilitated soil metabolic quotient (qCO) during the incubation period. After joint exposure to Pb and BDE209, C generally declined with increasing exposure concentration, following certain dose-response relationships. However, SBR and qCO were highly significantly stimulated ( p < 0.01), and more doses of Pb and BDE209 resulted in higher values. The results of these observations have provided a basic understanding of the potential ecological risk of Pb and BDE209 in soil at EWRSs. [ABSTRACT FROM AUTHOR]

Electron beam irradiation has shown potential as an alternative process for the treatment of industrial effluents that contain toxic organic chemicals. This study investigated the effectiveness of electron beam in degrading chloramphenicol (CAP) in aqueous solution. The degradation efficiency was 32.4 % at 1 kGy, 86.9 % at 5 kGy, and 100 % at 10 kGy. The total organic carbon (TOC) of CAP in aqueous solution declined 4.6 % at 1 kGy, 12.1 % at 5 kGy, and 17.1 % at 10 kGy of irradiation with electron beam. The CAP degradation products after irradiation were CAP1 ([M + H] m/z 307.1), CAP2 ([M + H] m/z 291.1), and CAP3 ([M + H] m/z 321.1). The degradation products were tested for microbial toxicity against Escherichia coli, Pseudomonas putida, and Bacillus subtilis and did not show any toxic antimicrobial effects caused by the CAP degradation products after irradiation with electron beam. The results of this study suggest that electron beam irradiation is the best technology for the comprehensive treatment of veterinary antibiotics at wastewater treatment plants. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) may affect bioavailability and toxicity of organic contaminants due to their adsorption properties. Recent studies have observed the influence of multiwalled carbon nanotubes (MWNTs) on the fate of polycyclic aromatic hydrocarbons (PAHs) and other organic contaminants. Greenhouse studies (49 d) were conducted with alfalfa plants in two different soil types. Four treatment conditions (0, 25, 50, or 100 mg/kg MWNTs+100 mg/kg PAHs mixture-pyrene and phenanthrene) were tested in order to determine their effects on soil microbial community composition and PAH residues. Microbial community structure in the two highest treatments (50 mg/kg and 100 mg/kg MWNTs) showed a dramatic shift in the presence of MWNTs in sandy loam soil (1% organic matter) in comparison to the control (0 mg/kg MWNTs). Many microbial fatty acid methyl ester (FAMEs) markers (i15:0, 16:1ω5c, 10Me17:0, 10Me16:0) were missing in the control soil. However, there was a lower abundance of these FAMEs in the 25 mg/kg MWNT treatment (except 10Me17:0) and a higher presence of these FAMEs in the 50 mg/kg and 100 mg/kg MWNT treatments compared to control. In contrast, microbial community composition was not influenced by the MWNT treatments in sandy clay loam soil (5.9% organic matter). However, pyrene degradation in sandy clay loam soil significantly increased by 21% in the highest MWNT treatment group (100 mg/kg) and 9.34% in 50 mg/kg MWNT treatment. Under the conditions tested in this study, MWNTs significantly impacted the soil microbial community distribution and PAH degradation and effects were dependent on soil types, specifically organic matter content. [ABSTRACT FROM AUTHOR]

Highlights: [•] Toxicity of five different metal NPs against soil bacterial community as a function of time has been studied. [•] ZnO and Cu NPs did not change the structure of soil bacterial community when present in biosolids. [•] Ag nanoparticles, anatase and rutile TiO2 nanoparticles altered the structure of bacterial community. [ABSTRACT FROM AUTHOR]

Highlights: [•] The microbial toxicity of DNAN and its metabolites was assayed. [•] DNAN caused severe inhibition of methanogens, nitrifiers, and Aliivibrio fischeri. [•] The aromatic amine metabolites were generally less toxic than DNAN. [Copyright &y& Elsevier]