Sulfonamide Per- and Polyfluoroalkyl Substances Can Impact Microorganisms Used in Aromatic Hydrocarbon and Trichloroethene Bioremediation.

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.

The effect of TiO2 nanoparticles on bacterial growth: the effect of particle size and their structure - a systematic review.

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.

Effects of adsorbent carriers in modified ready biodegradability tests of quaternary ammonium salts.

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.

Blame It on the Metabolite: 3,5-Dichloroaniline Rather than the Parent Compound Is Responsible for the Decreasing Diversity and Function of Soil Microorganisms.

Pesticides are key stressors of soil microorganisms with reciprocal effects on ecosystem functioning. These effects have been mainly attributed to the parent compounds, while the impact of their transformation products (TPs) has been largely overlooked. We assessed in a meadow soil (soil A) the transformation of iprodione and its toxicity in relation to (i) the abundance of functional microbial groups, (ii) the activity of key microbial enzymes, and (iii) the diversity of bacteria, fungi, and ammonia-oxidizing microorganisms (AOM) using amplicon sequencing. 3,5-Dichloroaniline (3,5-DCA), the main iprodione TP, was identified as a key explanatory factor for the persistent reduction in enzymatic activities and potential nitrification (PN) and for the observed structural changes in the bacterial and fungal communities. The abundances of certain bacterial (Actinobacteria, Hyphomicrobiaceae, Ilumatobacter, and Solirubrobacter) and fungal (Pichiaceae) groups were negatively correlated with 3,5-DCA. A subsequent study in a fallow agricultural soil (soil B) showed limited formation of 3,5-DCA, which concurred with the lack of effects on nitrification. Direct 3,5-DCA application in soil B induced a dose-dependent reduction of PN and NO3--N, which recovered with time. In vitro assays with terrestrial AOM verified the greater toxicity of 3,5-DCA over iprodione. "Candidatus Nitrosotalea sinensis" Nd2 was the most sensitive AOM to both compounds. Our findings build on previous evidence on the sensitivity of AOM to pesticides, reinforcing their potential utilization as indicators of the soil microbial toxicity of pesticides in pesticide environmental risk analysis and stressing the need to consider the contribution of TPs in the toxicity of pesticides on the soil microbial community.IMPORTANCE Pesticide toxicity on soil microorganisms is an emerging issue in pesticide risk assessment, dictated by the pivotal role of soil microorganisms in ecosystem services. However, the focus has traditionally been on parent compounds, while transformation products (TPs) are largely overlooked. We tested the hypothesis that TPs can be major contributors to the soil microbial toxicity of pesticides using iprodione and its main TP, 3,5-dichloroaniline, as model compounds. We demonstrated, by measuring functional and structural endpoints, that 3,5-dichloroaniline and not iprodione was associated with adverse effects on soil microorganisms, with nitrification being mostly affected. Pioneering in vitro assays with relevant ammonia-oxidizing bacteria and archaea verified the greater toxicity of 3,5-dichloroaniline. Our findings are expected to advance environmental risk assessment, highlighting the potential of ammonia-oxidizing microorganisms as indicators of the soil microbial toxicity of pesticides and stressing the need to consider the contribution of TPs to pesticide soil microbial toxicity.

Zinc and lead detoxifying abilities of humic substances relevant to environmental bacterial species.

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 - 0.3mM and 0.3-0.5mM, 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 - 200mgL-1) to all microorganisms, while hymatomelanic acids reduced zinc toxicity to Pseudomonas chlororaphis PCL1391 at 200mgL-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.

Organismic-level acute toxicology profiling of reactive azo dyes.

In the present study, organismic-level acute toxicology profile of three reactive azo dyes, viz. Reactive Blue 221, Reactive Red 195, and Reactive Yellow 145, was investigated, by using bacterial (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Listeria monocytogenes, and Bacillus subtilis), fungal (Trichoderma asperellum, Aspergillus flavus, Fusarium fujikuroi, and Rhizoctonia solani), plant (Raphanus sativus, Triticum aestivum, Sorghum bicolor, and Phaseolus mungo), and aquatic (Artemia salina and Daphnia magna) specimens. Microbial test organisms (all the six bacteria and two fungi, i.e., T. asperellum and A. flavus) and D. magna were found to be relatively more sensitive towards the reactive azo dyes and their mixture, as the EC50 values were in the range of 80-330, 135-360, and 108-242 ppm for bacteria, fungi, and D. magna, respectively (but the effect was not acutely toxic). Moreover, the effect of dye mixture was comparable tothe individual dyes in almost all the tested microbial specimens. For plant seeds, the dye mixture was found to be relatively more inhibitory towards T. aestivum and R. sativus than the individual dyes. For S. bicolor and P. mungo seeds, the effect of the dye mixture was almost identical to the individual dyes. However, in all cases, EC50 values were in the range of 950-3500 ppm, which indicates a non-toxic effect on plant seed germination potential. Likewise, the dyes and their mixture were not acutely toxic for Artemia salina larvae (more sensitive to the dye mixture) and Daphnia magna neonates (EC50, 516-950 and 108-242 ppm, respectively).

Ecotoxicity assessment of ionic As(III), As(V), In(III) and Ga(III) species potentially released from novel III-V semiconductor materials.

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 O2 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 3.4mM, 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 0.02mM, which is lower than the regulated maximum allowable daily effluent discharge concentration (2.09mg/L or 0.03mM) 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.

The influence of multiwalled carbon nanotubes on polycyclic aromatic hydrocarbon (PAH) bioavailability and toxicity to soil microbial communities in alfalfa rhizosphere.

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.

Size-dependent influences of nanoplastics on microbial consortium differentially inhibiting 2, 4-dichlorophenol biodegradation.

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 (PS100) or 20 nm (PS20) was conducted to verify that PS-NPs had noticeable inhibitory effect on DCP biodegradation in a size-dependent manner. PS100 at 10 mg/L and 100 mg/L both prolonged the microbial stagnation compared to the control without PS-NPs; PS20 exacerbated greater, with PS20 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 PS100 and PS20 exposure, respectively, while the elevated LDH under PS20 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 PS100 and PS20 exposure. Specifically, PS100 downregulated amino acid metabolism, while PS20 stimulated certain pathways in response to more severe oxidative stress. Our findings give insights into PS-NPs environmental effects concerning microflora and biological degradation.

Nanobiochar Associated Ammonia Emission Mitigation and Toxicity to Soil Microbial Biomass and Corn Nutrient Uptake from Farmyard Manure.

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.

A review on mechanistic understanding of microplastic pollution on the performance of anaerobic digestion.

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.

Distinct effects of chemical- and bio- flocculants on the sludge acidogenic fermentation for volatile fatty acids production by affecting the acidogenic steps, microbial community structure and metabolic functions.

Flocculants play crucial roles in sludge treatment, while the specific impact of chemical and bio-flocculants on sludge anaerobic fermentation was unknown. This study unveiled the contrasting effects of chitosan (CTS) and poly­aluminum chloride (PAC) on volatile fatty acids (VFAs) generation during sludge fermentation. CTS supplementation resulted in 17.2 % increase in VFAs production, while PAC exposure led to 7.6 % reduction compared to the control. Further investigation revealed that CTS facilitated sludge solubilization and hydrolysis, thus providing sufficient organic substrates for VFAs generation. Additionally, environmental-friendly CTS exposure positively influenced the abundance and activity of functional anaerobes, as well as the expression of genes associated with VFAs biosynthesis. In contrast, PAC exposure resulted in the formation of larger sludge flocs, which hindered WAS solubilization and hydrolysis. Meanwhile, its potential microbial toxicity also impeded the microbial metabolic activity (i.e., genetic expressions), resulting in unsatisfactory VFAs production.

Glyphosate versus glyphosate based ionic liquids: Effect of cation on glyphosate biodegradation, soxA and phnJ genes abundance and microbial populations changes during soil bioaugmentation.

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.

Efficient biodegradation of Congo red dye using fungal consortium incorporated with Penicillium oxalicum and Aspergillus tubingensis.

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.

The Effects of Quinone Imine, a New Potent Nitrification Inhibitor, Dicyandiamide, and Nitrapyrin on Target and Off-Target Soil Microbiota.

Dicyandiamide (DCD) and nitrapyrin (NP) are nitrification inhibitors (NIs) used in agriculture for over 40 years. Recently, ethoxyquin (EQ) was proposed as a novel potential NI, acting through its derivative quinone imine (QI). Still, the specific activity of these NIs on the different groups of ammonia-oxidizing microorganisms (AOM), and mostly their effects on other soil microbiota remain unknown. We determined the impact of QI, and comparatively of DCD and NP, applied at two doses (regular versus high), on the function, diversity, and dynamics of target (AOM), functionally associated (nitrite-oxidizing bacteria-NOB), and off-target prokaryotic and fungal communities in two soils mainly differing in pH (5.4 versus 7.9). QI was equally effective to DCD but more effective than NP in inhibiting nitrification in the acidic soil, while in the alkaline soil QI was less efficient than DCD and NP. This was attributed to the higher activity of QI toward AOA prevailing in the acidic soil. All NIs induced significant effects on the composition of the AOB community in both soils, unlike AOA, which were less responsive. Beyond on-target effects, we noted an inhibitory effect of all NIs on the abundance of NOB in the alkaline soil, with Nitrobacter being more sensitive than Nitrospira. QI, unlike the other NIs, induced significant changes in the composition of the bacterial and fungal communities in both soils. Our findings have serious implications for the efficiency and future use of NIs on agriculture and provide unprecedented evidence for the potential off-target effects of NIs on soil microbiota. IMPORTANCE NIs could improve N use efficiency and decelerate N cycling. Still, we know little about their activity on the distinct AOM groups and about their effects on off-target soil microorganisms. Here, we studied the behavior of a new potent NI, QI, compared to established NIs. We show that (i) the variable efficacy of NIs across soils with different pH reflects differences in the inherent specific activity of the NIs to AOA and AOB; (ii) beyond AOM, NIs exhibit negative effects on other nitrifiers, like NOB; (iii) QI was the sole NI that significantly affected prokaryotic and fungal diversity. Our findings (i) highlight the need for novel NI strategies that consider the variable sensitivity of AOM groups to the different NIs (ii) identify QI as a potent AOA inhibitor, and (iii) stress the need for monitoring NIs' impact on off-target soil microorganisms to ensure sustainable N fertilizers use and soil ecosystem functioning.

Fate of bis-(4-tert-butyl phenyl)-iodonium under photolithography relevant irradiation and the environmental risk properties of the formed photoproducts.

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.

Bioconcentration potential and microbial toxicity of onium cations in photoacid generators.

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.

Dynamic modelling of tetrazolium-based microbial toxicity assay-a parametric proxy of traditional dose-response relationship.

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.

Development, formulation and optimization of a novel biocompatible ionic liquids dispersant for the effective oil spill remediation.

The application of chemical dispersants in marine oil spill remediation is comprehensively reported across the globe. But, the augmented toxicity and poor biodegradability of reported chemical dispersants have created necessity for their replacement with the bio-based green dispersants. Therefore, in the present study, we have synthesized five ionic liquids (ILs) namely 1-butyl-3-methylimidazolium lauroylsarcosinate, 1,1'-(1,4-butanediyl)bis(1-H-pyrrolidinium) dodecylbenzenesulfonate, tetrabutylammonium citrate, tetrabutylammonium polyphosphate and tetrabutylammonium ethoxylate oleyl ether glycolate, and formulated a water based ILs dispersant combining the synthesized ILs at specified compositions. The effectiveness of formulated ILs dispersant was found between 70.75% and 94.71% for the dispersion of various crude oils ranging from light to heavy. Further, the acute toxicity tests against zebra fish and grouper fish have revealed the practically non-toxic behaviour of formulated ILs dispersant with LC50 value greater than 100 ppm after 96 h. In addition, the formulated ILs dispersant has provided excellent biodegradability throughout the test period. Overall, the formulated new ILs dispersant is deemed to facilitate environmentally benign oil spill remediation and could effectively substitute the use of hazardous chemical dispersants in immediate future.

Synthesis, characterization, ecotoxicity and biodegradability evaluations of novel biocompatible surface active lauroyl sarcosinate ionic liquids.

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.