Technical Nonylphenol Research Articles

Long-Chain Alkylphenol Biodegradation Potential of Soil Ascomycota

A total of 11 ascomycete strains destructing technical nonylphenol (NP) and 4-tert-octylphenol (4-t-OP) were isolated from NP-contaminated soddy-podzolic loamy soil (Leningrad Region, Russia). The isolates proved capable of degrading NP and 4-t-OP at a high load (300 mg/L). The most efficient Fusarium solani strain 8F degraded alkylphenols (APs) both in cometabolic conditions and in the absence of additional carbon and energy sources. A decrease in APs was due to biodegradation or biotransformation by the strain and, to a minor extent, absorption by fungal cells. NP and 4-t-OP half-lives were, respectively, 3.5 and 6.4 h in cometabolic conditions and 9 and 19.7 h in the absence of additional carbon and energy sources. Amounts of the lipid peroxidation product malondialdehyde (MDA) and reduced glutathione (GSH) increased during NP and 4-t-OP biodegradation in cometabolic conditions by 1.7 and 2 times, respectively, as compared with a control. A high GSH level in F. solani 8F cells potentially implicated the metabolite in both AP biodegradation and strain resistance to oxidative stress. The study is the first to report on the NP and 4-t-OP degradation by the ascomycete F. solani in cometabolic conditions and in the absence of additional carbon and energy sources. The high AP degradation potential of soil ascomycetes was assumed to provide a basis for new environmentally safe bioremediation technologies for purification of soils and natural and waste waters contaminated with endocrine disruptors.

Long-Chain Alkylphenols Biodegradation Potential of the Soil <i>Ascomycota</i>

A total of 11 strains ascomycetes-destructors of technical nonylphenol (NP) and 4-tert-octylphenol (4-t-OP) were isolated from nonylphenol-contaminated soddy-podzolic loamy soil (Leningrad Region, Russia). Fungal isolates are able to degrade NP and 4-t-OP at a high load (300 mg/L). The most effective Fusarium solani 8F strain has the ability to degrade alkylphenols (AP) both under cometabolic conditions and without additional carbon and energy sources. The decrease in AP is due to the processes of biodegradation and/or biotransformation by the studied strain and, to a small extent, due to sorption by fungal cells. The NP and 4-t-OP half-life under cometabolic conditions is 3.5 and 6.4 hours, respectively, and without additional carbon and energy sources, 9 and 19.7 hours, respectively. The amount of the lipid peroxidation product, malondialdehyde, as well as the reduced glutathione content in the process of NP and 4-t-OP biodegradation under cometabolic conditions increases by 1.7 and 2 times, respectively, compared with the control. The high level of reduced glutathione in F. solani 8F cells may indicate the participation of this metabolite both in the processes of AP biodegradation and in providing strain resistance to oxidative stress. To our knowledge, this is the first report on the degradation of NP and 4-t-OP by ascomycetous fungus F. solani both under cometabolic conditions and without additional carbon and energy sources. The revealed high potential of soil ascomycetes to degrade alkylphenols can be the basis for new environmentally safe bioremediation technologies for the purification of endocrine-disruptors conta-minated soils, natural and waste waters.

Comparative analysis of performance of fabricated nitrogen-doped carbon-nanotubes, silicon/germanium dioxide embedded polyethersulfone membranes for removal of emerging micropollutants from water

The occurrence of emerging micropollutants (EMPs) in water is a new challenge to scientific community and ecosystems health worldwide. There remains widespread data gaps regarding effective removal of EMPs from water. In this study, nitrogen-doped carbon nanotubes/polyethersulfone (N-CNT/PES), silicon dioxide (silica) (SiO2) and germanium dioxide (GeO2) embedded polyethersulfone (PES) membranes were fabricated using phase inversion method. A comparative multivariate statistical analysis was done to comprehend major underlying factors behind the performance of the membranes in the removal of EMPs from water using the cross flow filtration system. The EMPs were detected and quantified using GC xGc-HRTOFMS Strong statistically significant positive correlations were observed between removal efficiency of all analytes, namely carbamazepine (CBZ), tonalide (AHTN), galaxolide (HHCB), caffeine (CAF), technical 4-nonylphenol (NP) and bisphenol A (BPA) and various membrane characteristics such as pore density number, ultimate tensile strength, Young's modulus, flux recovery ratio (p-value < 0.05, 95% confidence level). Statistically significant negative corrections were observed between the removal efficiency of the EMPs with pore size, contact angle and surface roughness. The EMPs were observed to be removed from real water samples in the following order: HHCB > NP > AHTN > BPA > CBZ > CAF. The removal of the EMPs followed the order of the decrease in hydrophobicity. It was also observed that modification of PES membranes with N-CNTs, SiO2 and GeO2 nanoparticles enhanced the fouling resistance of the membranes. Generally, the performance of the fabricated membranes in the removal of all analytes followed the following order: SiO2/PES > GeO2/PES > N-CNT/PES > pristine PES. The order of increase in water flux (L/m2/h) was observed to be PES (200.60 ± 0), N-CNT/PES (265.01 ± 0), GeO2/PES (300.01 ± 0) and SiO2/PES (305.88 ± 0). However, lower nanoparticle loadings were required to bring statistically significant improvements in performance and characteristics of the N-CNT/PES membranes than that in the SiO2/PES and GeO2/PES membranes. The results showed that the capability fabricated membranes in removing EMPs from water was superior to the majority of methods reported in the literature.

QuEChERS-Based Methodology for the Screening of Alkylphenols and Bisphenol A in Dairy Products Using LC-LTQ/Orbitrap MS

A simple methodology was developed for the determination of four Endocrine Disrupting Chemicals (EDCs) in dairy products. The EDCs included alkylphenols (4-tert-octylphenol, technical nonylphenol isomers, 4-nonylphenol) and bisphenol-A. The methodology consisted of a quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction followed by liquid chromatography (LC) coupled to the hybrid LTQ/Orbitrap mass spectrometer (MS). The high resolution (HR) analysis provided the required selectivity demonstrating excellent sensitivity and enabled the high-mass accuracy of the analytes within short time of analysis, after a chemometric optimization of the instrument parameters. An experimental design was employed for the estimation of the effect of different parameters on the QuEChERS extraction efficiency to obtain the optimum conditions. Method validation proved that analysis exhibited excellent linearity (R2 &gt; 0.9966), low enough precision (0.6 to 13.3%) and recoveries in the range of 91 to 108%. Limits of detection (LOD &lt; 6.5 ng g−1) and quantification (LOQ &lt; 20 ng g−1) as well as matrix effects (ME) were also evaluated. The optimized method was successfully applied to analyze dairy commodities varying in fat content and packaging material including milk, yogurts and infant formulae. Detected concentration levels (MDL-10.4 ng g−1) for bisphenol-A BPA in milk samples resulted in 0.36% of TDI for the medium case (average BPA concentrations) and 1.15% of TDI for the worst case (maximum BPA concentration).

Sorption and Biodegradation of Octyl- and Nonylphenols by the Cyanobacterium Planktothrix agardhii (Gomont) Anagn. &amp; Komárek

The removal of endocrine-disrupting xenobiotics, technical nonylphenol (NP) and 4-tert-octylphenol (OP), from aquatic environment by the cyanobacterium Planktothrix agardhii has been studied. It is shown that nonyl- and octylphenols are removed from aqueous medium in the presence of the cyanobacterium P. agardhii mainly via abiotic pathways—photolysis and hydrolysis—and biodegradation by cyanobacterial cells rather than by adsorption and accumulation in the cells. P. agardhii has a higher destructive and sorption ability for nonylphenol compared to octylphenol. The results indicate the possibility of self-purification of water bodies contaminated with alkylphenols with the participation of the mass species of cyanobacteria Planktothrix agardhii.

Application of silica and germanium dioxide nanoparticles/ polyethersulfone blend membranes for removal of emerging micropollutants from water

One of the current global issues of increasing environmental-health concern is the ubiquitous occurrence of emerging micropollutants (EMPs) in aquatic environments. Among these EMPs, bisphenol A (BPA), technical 4-nonylphenol (NP), tonalide (AHTN), carbamazepine (CBZ), caffeine (CAF) and galaxolide (HHCB) find their way into aquatic environments as a result of their ever increasing production and consumption coupled with their incomplete removal in conventional water and wastewater treatment plants. This study fabricated silicon dioxide (silica) (SiO2) and germanium dioxide (GeO2) embedded polyethersulfone (PES) blend membranes using phase inversion method for the removal of EMPs from water samples collected from North West Province, South Africa. The EMPs were extracted and enriched by auto-trace solid-phase extraction and analyzed using comprehensive two dimensional gas chromatography coupled to time of flight mass spectrometry (GCxGC-TOFMS). The fabricated membranes' permeation properties were determined by computing the pure water flux and EMPs' rejection. The water flux was observed to increase with increase in transmembrane pressure as well as increase in SiO2 and GeO2 nanoparticle loadings in the polymer matrices. Compared to the pristine PES, the contact angles for the SiO2/PES and GeO2/PES membranes were much lower, showing increased hydrophilicity of the membranes with increase in SiO2 and GeO2 nanoparticle loadings in the matrices. The mean EMPs' concentrations (ng/L) ranges in the feed were found to be: BPA (5.19 ± 0.8 to 53.60 ± 4.25), CAF (6.09 ± 0.00 to 49.96 ± 3.45), CBZ (0.68 ± 0.00 to 3.06 ± 0.74), HHCB (21.31 ± 4.24 to 13.31 ± 14.8), AHTN (8.31 ± 2.23 to 141.82 ± 21.70), and NP (0–174.99 ± 14.5). Even though SiO2/PES membranes showed slightly higher EMPs' removal efficiencies than their GeO2/PES counterparts, both membranes showed the highest and lowest removal efficiencies range of 97.85–99.00% (for HHCB) and 87.42–93.00% (for CAF), respectively. The results showed superiority in capability of the fabricated nanocomposite membranes in removing EMPs from water.

Assessment of endocrine disruption and oxidative potential of bisphenol-A, triclosan, nonylphenol, diethylhexyl phthalate, galaxolide, and carbamazepine, common contaminants of municipal biosolids

The use of biosolids as a soil conditioner and fertiliser is hindered by the limited knowledge on the risks of micro-contaminants they contain. This study investigated the binding of six organic contaminants commonly found in biosolids, to the estrogen (ER), androgen (AR), aryl hydrocarbon (AhR), and transthyretin (TTR) receptors and their redox activity. Triclosan (TCS), bisphenol-A (BPA), and technical nonylphenol (TNP) had affinity for the TTR with relative potencies of 0.3, 0.03, and 0.076 respectively. Further, binding to TTR was the only toxicological response observed for carbamazepine, which induced sub-maximal response and relative potency of 0.0017. Estrogenic activity was induced by BPA, galaxolide (HHCB), diethylhexyl phthalate (DEHP) and TNP with BPA having the strongest potency of 5.1 × 10−6 relative to estradiol. Only BPA showed androgenic activity but it was not quantifiable. BPA also showed anti-androgenic activity along with TCS, HHCB, and TNP in the order of TNP > HHCB > TCS ~ BPA (relative potencies 0.126, 0.042, 0.032, 0.03). No compounds exhibited anti-estrogenic or AhR activity, or were redox-active in the dithiothreitol assay. The results highlight the multiple modes of action through which these compounds may impact exposed organisms, and the concentrations at which effects may occur. This allows assessment of the likelihood of effects being observed at environmental concentrations, and the potential contribution of these compounds.

Hydrochemical modelling of water quality in terms of emerging micropollutants in Mpumalanga, Gauteng and North West Provinces

Emerging micropollutants (EMPs) are ubiquitous in aquatic systems and are associated with a wide range of eco-toxicological effects worldwide. There remains a lack of scientific understanding of the major underlying hydrochemical factors behind variations in concentration heterogeneities of EMPs in time and space. This study was therefore conducted to determine major hydrochemical processes controlling water quality and the occurrence of EMPs mainly, carbamazepine (CBZ), tonalide (AHTN), galaxolide (HHCB), caffeine (CAF), technical 4-nonylphenol (NP) and bisphenol A (BPA) in water from Mpumalanga, Gauteng and North West Provinces in South Africa. Grab water samples were collected bi-monthly between June 2014 and April 2016 from 44 water sources using standard sampling procedures. BPA, NP, CAF, HHCB, AHTN, CBZ were extracted, cleaned and enriched using autotrace-SPE at neutral pH and analyzed using GC × GC-TOFMS. Kruskal Wallis-test was used to test for temporal variations in occurrence of the analytes. The Geochemist's Workbench® Release 11 software, Surfer Golden Graphics for surface mapping, PHREEQC software and bivariate ion plots were used determine the major hydrogeochemical processes. The mean concentrations of EMPs varied from 3.48 μg/L for CAF to 421.53 μg/L for HHCB. Although the Kruskal Wallis test revealed no any statistically significant temporal variations in concentrations of the analytes in water samples at 95% confidence level, their occurrence and distribution vary spatially with BPA being the most widely distributed EMP and was present in 62% of the sampled sites. Municipal waste water inputs, agricultural pollution, ion-exchange reactions, carbonate and silicate weathering were the major processes controlling water quality in the study area. This study may assist water resource managers to ably address and manage water pollution resulting from a number of natural and anthropogenic hydrochemical processes in the study area.

Fate and effects of nonylphenol in the filamentous fungus Penicillium expansum isolated from the bottom sediments of the Gulf of Finland

Abstract Nonylphenol (NP) is the most abundant environmental pollutant that is classified as an endocrine disruptor, and it originates from the degradation of nonylphenol ethoxylates, which are widely used as industrial surfactants. It has been referred to in a list of substances of particular risk to the Baltic Sea, in a list of priority hazardous substances in the Water Frame Directive, and in the 3rd draft Working Document on Sludge, developed by the EU. In this study, the fate and effects of NP in the filamentous fungus Penicillium expansum isolated from the bottom sediments of the coastal zone of the eastern Gulf of Finland were investigated in laboratory experiments. This strain was more tolerant to technical nonylphenol (tNP) compared to other types of aquatic organisms, such as fish, protozoa, and algae. The toxicity concentration values of tNP in Penicillium expansum were EC 50 20 mg L − 1 and ЕС 90 > 100 mg L − 1 . The activity level of hydrolytic enzymes, cellulases and amylases decreased significantly in the tNP treatments. Given the significant role played by terrestrial fungi in the transformation of organic substrate into bottom sediment, such an effect from tNP on fungi could disturb the regulatory mechanisms and balance between the biosynthesis and biodegradation of organic matter in aquatic ecosystems as well as the formation of cenotic relations in aquatic biocenoses. Oxidative stress induced by tNP has been found to increase the synthesis of enzymatic protection factors, such as superoxide dismutase, catalase and nonenzymatic factors (melanin-like pigments and extracellular polysaccharides). This research indicated that the malondialdehyde concentration (the biochemical marker of lipid peroxidation) in the cells of the fungus decreased with increasing antioxidation factors. Penicillium expansum was able to decrease the tNP concentration in the culture medium. The removal of tNP was mainly caused by fungal degradation rather than by simple sorption and accumulation in the cells. Because terrestrial fungi play a significant role in the function of the heterotrophic block of bottom sediments and because tNP has become an increasingly persistent toxic organic and endocrine disruptor, these results may be ecologically relevant for aquatic systems. The results from this study demonstrate a potential application of this fungal species for the removal of tNP from the environment.

Enantioselective separation of defined endocrine-disrupting nonylphenol isomers.

Nonylphenol is in the focus of worldwide endocrine-disrupter research and accountedfor as a priority hazardous substance of the Water Framework Directive of the European Union. Technical nonylphenol consists of a very complex mixture of isomers and enantiomers. As estrogenic effect and degradation behavior in environmental processes of single nonylphenols are heavily dependent on the structure of the nonyl side chain, it is absolutely necessary to consider the nonylphenol problem from an isomer and enantiomer-specific viewpoint. In this study, an enantiomer-specific separation of eight defined synthesized nonylphenol isomers by five different special chiral cyclodextrin columns was performed underivatized and after methylation, silylation, and acylation. This work demonstrates that three columns out of the investigated five show an excellent separation behavior for the studied different nonylphenol isomers and can be used for the enantiomer-specific determination of nonylphenols in food, other biological matrices, and environmental samples in the future. Graphical abstract Enantiomeric pair of 4-NP170 (4-[1-ethyl-1,3,3-trimethylbutyl]phenol).

The impact of variations of influent loading on the efficacy of an advanced tertiary sewage treatment plant to remove endocrine disrupting chemicals

The impact of changes in influent load on the removal of endocrine disrupting chemicals (EDCs) by sewage treatment has not been fully characterised. This study assessed the efficacy of an advanced tertiary sewage treatment plant (STP) to remove EDCs during normal and peak flow events of sewage influent using trace chemical analysis of selected EDCs and four estrogenic in vitro bioassays. During the summer holiday season, influent volume increased by 68%, nutrient concentrations by at least 26% and hydraulic retention time was reduced by 40% compared with base flow conditions. Despite these pressures on the treatment system the concentrations and mass loading of estrone, 17β-estradiol, estriol, Bisphenol A, 4-t-octylphenol and technical nonylphenol were not significantly higher (p>0.05) during the peak flow conditions compared with base flow conditions. Chemical analysis and in vitro bioassays showed that the efficacy of the STP in removing EDCs was not affected by the different loadings between baseline and peak flow regimes. This study demonstrates that large flow variations within the design capacity of advanced multi-stage STPs should not reduce the removal efficacy of EDCs.

Biochemical and physicochemical processes contributing to the removal of endocrine-disrupting chemicals and pharmaceuticals by the aquatic ascomycete Phoma sp. UHH 5-1-03.

The environmentally widespread micropollutants bisphenol A (BPA), carbamazepine (CBZ), 17α-ethinylestradiol (EE2), diclofenac (DF), sulfamethoxazole (SMX), technical nonylphenol (t-NP) and triclosan (TCS) were used to assess the potential of the laccase-producing freshwater ascomycete Phoma sp. strain UHH 5-1-03 for micropollutant removal and to provide quantitative insights into the mechanisms involved. Biotransformation rates observed with whole fungal cells followed the rank order EE2 ≫ BPA > TCS > t-NP > DF > SMX > CBZ. Biosorption onto fungal mycelia was prominent for BPA, EE2, TCS and t-NP and insignificant for CBZ, DF and SMX. Enzymatic removal rates investigated with cell-free, laccase-containing culture supernatants of Phoma sp. followed the rank order EE2 > BPA > DF > t-NP > TCS and were insignificant for SMX and CBZ. Mass spectrometry-assisted investigations addressing metabolite formation from unlabelled and (13)C6-labelled DF and SMX yielded DF metabolites indicating hydroxylation, cyclisation and decarboxylation reactions, as well as oxidative coupling typical for laccase reactions. For SMX, several products characterised by lower molecular masses than the parent compound were found, and indications for deamination and formamide formation were obtained. Summarising, the obtained results suggest that the extracellular laccase of Phoma sp. largely contributes to fungal biotransformation of EE2, BPA, DF, TCS and t-NP, together with cell-associated enzymes such as, e.g. cytochrome P450 monooxygenases suggested by the appearance of hydroxylated metabolites from DF. Laccase does not seem to play any role in the metabolisation of SMX and CBZ, where yet to be identified cell-associated enzymes have to be considered instead.

Occurrence of halogenated transformation products of selected pharmaceuticals and personal care products in secondary and tertiary treated wastewaters from southern California.

Final effluent samples from 10 southern California (United States) wastewater treatment facilities, employing four distinct treatment schemes, were surveyed for selected pharmaceuticals, personal care products (PPCPs), alkylphenols, and 21 of their halogenated disinfection byproducts. Chlorinated and brominated standards and isotopically labeled internal standards were synthesized and purified to confirm and more accurately quantify selected disinfection byproducts of salicylic acid, bisphenol A, gemfibrozil, naproxen, diclofenac, technical 4-nonylphenol, and 4-tert-octylphenol using high-performance liquid chromatography and tandem mass spectrometry. Concentrations of parent compounds ranged from <10 to 3830 ng/L (gemfibrozil), and those of chloro/bromo byproducts ranged from <4 to 370 ng/L (dibromo nonylphenol). The highest concentrations of parent compounds were measured in effluent that was not subjected to tertiary treatment. The chlorinated and brominated byproduct concentration may be affected by the influent concentration of parent compounds, hydraulic retention times, and chlorine contact times. Salicylic acid was readily halogenated, which is evident from the ratio of halogenated to nonhalogenated species. There were no measured chlorinated byproducts of bisphenol A despite occasionally high concentrations of the parent compound. Not surprisingly, higher concentrations of most brominated species were measured in the treatment plant with the highest bromide concentrations. These results demonstrate the occurrence of novel halogenated byproducts of PPCPs that have limited toxicological data and significant uncertainty with regard to their risk to ecological systems.

Development and validation of a liquid chromatography isotope dilution mass spectrometry method for the reliable quantification of alkylphenols in environmental water samples by isotope pattern deconvolution

We present here a new measurement method for the rapid extraction and accurate quantification of technical nonylphenol (NP) and 4-t-octylphenol (OP) in complex matrix water samples by UHPLC-ESI-MS/MS. The extraction of both compounds is achieved in 30min by means of hollow fiber liquid phase microextraction (HF-LPME) using 1-octanol as acceptor phase, which provides an enrichment (preconcentration) factor of 800. On the other hand we have developed a quantification method based on isotope dilution mass spectrometry (IDMS) and singly 13C1-labeled compounds. To this end the minimal labeled 13C1-4-(3,6-dimethyl-3-heptyl)-phenol and 13C1-t-octylphenol isomers were synthesized, which coelute with the natural compounds and allows the compensation of the matrix effect. The quantification was carried out by using isotope pattern deconvolution (IPD), which permits to obtain the concentration of both compounds without the need to build any calibration graph, reducing the total analysis time. The combination of both extraction and determination techniques have allowed to validate for the first time a HF-LPME methodology at the required levels by legislation achieving limits of quantification of 0.1ngmL−1 and recoveries within 97–109%. Due to the low cost of HF-LPME and total time consumption, this methodology is ready for implementation in routine analytical laboratories.

Oxidation of nonylphenol and octylphenol by manganese dioxide: Kinetics and pathways

Due to their potent estrogenicity and ubiquitous occurrence, non-ionic surfactant metabolites nonylphenol (NP) and octylphenol (OP) are of significant concern. Abiotic chemical oxidation by naturally abundant metal oxides may be an important route of their environmental attenuation, but is poorly understood. We investigated the reaction kinetics and pathways of NP and OP with MnO2. At pH 5.5 and 100 mg/L δ-MnO2, 92, 84 and 76% of 4-n-NP, 4-tert-OP and technical nonylphenol (tNP) was transformed in 90 min, respectively. A further experiment using a Mn-containing soil and Mn-removed soil confirmed that soil MnO2 caused NP removal. Multiple reaction products, including hydroquinone, hydroxylated products, dimers and trimers were identified through fragmentation analysis by GC–MS/MS and UPLC–MS/MS, allowing the construction of tentative pathways. This study suggested that abiotic oxidation by MnO2 may contribute to the dissipation of tNP, 4-n-NP, 4-tert-OP and their analogues in the natural environment.

Guidelines for alkylphenols estimation as alkylphenol polyethoxylates pollution indicator in wastewater treatment plant effluents

A solid-phase microextraction coupled with a gas chromatography-mass spectrometry method has been developed for the estimation of technical nonylphenol in the presence of other endocrine disruptors, belonging to different chemical families. The profile of the technical nonylphenol found in real samples was tested, and, given that it was similar to that provided for the standard used, reliable results were obtainable. Endocrine disruptors such as 4-n-nonylphenol, bisphenol A and 4-tert-octylphenol were simultaneously analysed. The best conditions achieved enabled the analysis of all analytes using a sample volume of 15 mL or even only 300 μL. Using such a low sample volume reduced the filtration process, which, in turn, significantly reduced the analysis time. The limits of detection achieved ranged between 0.006 and 0.5 μg L−1. Wastewater samples collected in three sampling campaigns (2006, 2007 and 2008) revealed an important presence of 4-tert-octylphenol and technical nonylphenol in several sampling points especially during the summer season. This finding is indicative of alkylphenol polyethoxylates pollution.

Comparative evaluation of nonylphenol isomers on steroidogenesis of rat Leydig Cells

Nonylphenol (NP) has been proven to be one of the most investigated xenohormones interacting with the estrogen receptor. Technical nonylphenol (t-NP) contains at least 20 para-substituted isomers. It has been shown that NP isomers vary in their estrogenic potency. So the use of mixtures or impure substances can lead to misinterpretations and unsatisfying conclusions. In the present study, experiments were performed to examine effects of NP isomers on steroidogenesis of rat Leydig cells. Primary cultured Leydig cells were exposed to NP isomers (p33-NP, p262-NP, p353-NP, p363-NP) at the optimized inhibitory concentration 5μmol/L for 6h. NP isomers showed various degrees of inhibition of testosterone biosynthesis, with p363-NP leading to the most significant decrease and others sharing the similar efficacy. The expression of 3b-HSD, Cyp11a1, Star and the apoptosis of Leydig cells were further measured to investigate the underlying mechanisms. We demonstrated that NP isomers can affect the steroidogenesis of rat Leydig cells, at least in part, through their influence on gene expression and cell apoptosis, but varied in their individual degree. However, the final results were not completely coincident with their estrogenic potency tested in vitro, which implies that effects of NP isomers on steroidogenesis appear to be mediated through some other underlying mechanisms besides their various estrogenic potency.

Formation of Toxic 2-Nonyl-p-Benzoquinones from α-Tertiary 4-Nonylphenol Isomers during Microbial Metabolism of Technical Nonylphenol

In many environmental compartments, microbial degradation of α-quaternary nonylphenols proceeds along an ipso-substitution pathway. It has been reported that technical nonylphenol contains, besides α-quaternary nonylphenols, minor amounts of various α-H, α-methyl substituted tertiary isomers. Here, we show that potentially toxic metabolites of such minor components are formed during ipso-degradation of technical nonylphenol by Sphingobium xenophagum Bayram, a strain isolated from activated sewage sludge. Small but significant amounts of nonylphenols were converted to the corresponding nonylhydroquinones, which in the presence of air oxygen oxidized to the corresponding nonyl-p-benzoquinones-yielding a complex mixture of potentially toxic metabolites. Through reduction with ascorbic acid and subsequent analysis by gas chromatography-mass spectrometry, we were able to characterize this unique metabolic fingerprint and to show that its components originated for the most part from α-tertiary nonylphenol isomers. Furthermore, our results indicate that the metabolites mixture also contained several α, β-dehydrogenated derivatives of nonyl-p-benzoquinones that originated by hydroxylation induced rearrangement, and subsequent ring and side chain oxidation from α-tertiary nonylphenol isomers. We predict that in nonylphenol polluted natural systems, in which microbial ipso-degradation is prominent, 2-alkylquinone metabolites will be produced and will contribute to the overall toxicity of the remaining material.

Determination of Nonylphenol and Octylphenol in Seawater Samples Using Solid-Phase Microextraction Procedures Coupled to Gas Chromatography–Mass Spectrometry

The solid-phase microextraction (SPME) technique with on-fiber derivatization coupled to gas chromatography–mass spectrometry was evaluated for the analysis of technical nonylphenol (NP) and octylphenol (OP). The optimization of operating conditions influencing the performances of SPME and derivatization were studied in detail. The optimised method was linear over the range studied and showed good level of precision, with a RSD lower than 10% and detection limits at and 0.003 μgL−1 for OP and 0.032μgL−1 for NP, respectively. The results obtained from different seawater samples revealed the presence of the target compounds, at levels ranging between 0.034 and 0.186 μgL−1.

Differential Regulation by Organic Compounds and Heavy Metals of Multiple Laccase Genes in the Aquatic Hyphomycete Clavariopsis aquatica

To advance the understanding of the molecular mechanisms controlling microbial activities involved in carbon cycling and mitigation of environmental pollution in freshwaters, the influence of heavy metals and natural as well as xenobiotic organic compounds on laccase gene expression was quantified using quantitative real-time PCR (qRT-PCR) in an exclusively aquatic fungus (the aquatic hyphomycete Clavariopsis aquatica) for the first time. Five putative laccase genes (lcc1 to lcc5) identified in C. aquatica were differentially expressed in response to the fungal growth stage and potential laccase inducers, with certain genes being upregulated by, e.g., the lignocellulose breakdown product vanillic acid, the endocrine disruptor technical nonylphenol, manganese, and zinc. lcc4 is inducible by vanillic acid and most likely encodes an extracellular laccase already excreted during the trophophase of the organism, suggesting a function during fungal substrate colonization. Surprisingly, unlike many laccases of terrestrial fungi, none of the C. aquatica laccase genes was found to be upregulated by copper. However, copper strongly increases extracellular laccase activity in C. aquatica, possibly due to stabilization of the copper-containing catalytic center of the enzyme. Copper was found to half-saturate laccase activity already at about 1.8 μM, in favor of a fungal adaptation to low copper concentrations of aquatic habitats.