Melatonin inhibits atrazine-induced mitochondrial impairment in cerebellum of mice: Modulation of cGAS-STING-NLRP3 axis-dependent cell pyroptosis.

The global prevalence of Neurological disorders has increased alarmingly in response to environmental and lifestyle changes. Atrazine (ATZ) is a difficult to degrade soil and water pollutant with well-known neurotoxicity. Melatonin (MT), an antioxidant with chemoprotective properties, has a potential therapeutic effect on cerebellar damage caused by ATZ exposure. The aim of this study was to explore the effects and underlying mechanisms of MT on the cerebellar inflammatory response and pyroptosis induced by ATZ exposure. In this study, C57BL/6J mice were treated with ATZ (170 mg/kg BW/day) and MT (5 mg/kg BW/day) for 28 days. Our results revealed that MT alleviated the histopathological changes, ultrastructural damage, oxidative stress and decrease of mitochondrial membrane potential (ΔΨm) in the cerebellum induced by ATZ exposure. ATZ exposure damaged the mitochondria leading to release of mitochondrial DNA (mtDNA) to the cytoplasm, MT activated the cyclic GMP-AMP synthetase interferon gene stimulator (cGAS-STING) axis to alleviate inflammation and pyroptosis caused by ATZ exposure. In general, our study provided new evidence that the cGAS-STING-NLRP3 axis plays an important role in the treatment of ATZ-induced cerebellar injury by MT.

Biochemical and gene expression alterations due to individual exposure of atrazine, dichlorvos, and imidacloprid and their combination in zebrafish.

In environmental toxicology, combined toxicity has emerged as an important concern. Atrazine (ATZ), dichlorvos (DIC), and imidacloprid (IMD) are the major pesticides, extensively used to control insect, flies, mosquitoes, and weed. Here, we investigate whether the exposure to three different types of pesticides individually and in combination for 24 h alters antioxidant enzyme responses in zebrafish (Danio rerio). Oxidative stress parameters (biochemical and mRNA expression), acetylcholinesterase (AChE) activity, and Metallothionein-II (MT-II) mRNA expression levels were measured. Present work includes toxicological assessment of individual and combined (CMD) exposure of ATZ (185.4 µM), DIC (181 µM), IMD (97.8 µ), and CMD (ATZ 92.7 µM + DIC 90.5 µM + IMD 48.9 µM), in the liver, kidney, and brain of adult zebrafish. Lipid peroxidation (LPO), glutathione (GSH) content, AChE, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activity along with mRNA expression of SOD, CAT, GPx, and MT-II were evaluated. Briefly, LPO, GSH content, the activity of AChE, and all antioxidant enzymes enhanced significantly in individual exposure, which was further altered in the CMD group. The mRNA expression of SOD, CAT, GPx, and MT-II in the liver and kidney showed significant down-regulation in all exposed groups. In the brain, significant upregulation in mRNA expression of SOD, CAT, GPx, and MT-II was observed in DIC and IMD groups, while ATZ and CMD showed significant downregulation except for GPx. Findings postulate that the CMD group exhibits synergistic toxic manifestation. The present study provides the baseline data on the combined toxic effects of pesticides and suggests regulating the use of pesticides.

TDP-43 is a potential marker of dopaminergic neuronal damage caused by atrazine exposure.

Atrazine (ATR) is one of the herbicides widely used worldwide. Meanwhile, it is an environmental endocrine disruptor that can cross the blood-brain barrier and cause damage to the endocrine-nervous system, especially by affecting the normal secretion of dopamine (DA). Regrettably, effector markers and cascade response mechanisms in damaged dopaminergic neurons induced by ATR exposure remain elusive. In this paper, we focus on investigating aggregation and position change of transactive response DNA-binding protein-43 (TDP-43) after ATR exposure, and illustrating whether TDP-43 can serve as a potential marker of mitochondrial dysfunction which causes damage to dopaminergic neurons. In our study, we used rat adrenal pheochromocytoma cell line 12 (PC12) to establish an in vitro model of dopaminergic neurons. After PC12 was intervened by ATR, we found reduced DA cycling and DA levels, and that TDP-43 aggregated continuously in the cytoplasm and then translocated to mitochondria. Furthermore, the studies we have performed showed that the translocation can cause mitochondrial dysfunction through activating the unfolded mitochondrial protein response (UPRmt), ultimately causing damage to dopaminergic neuron. The research we have done suggests that TDP-43 can serve as a potential effector marker of dopaminergic neuron damaged caused by ATR exposure.

Atrazine induces phagocytotic dysfunction of microglia depends on nucleocytoplasmic translocation of acetylated HMGB1.

Atrazine (ATR) is a widely applied herbicide which was named an environmental endocrine disrupting chemical (EDC). Increasing evidence indicates ATR causes neurotoxic effects resulting in central nervous system (CNS) disease. As the primary immunocytes in the CNS, microglia cells carry out their phagocytosis to maintain the CNS microenvironment by preventing damage from healthy cells. However, the mechanism in which ATR affects the phagocytic function of microglia remains unclear. The present study was designed to investigate the effect of ATR on the phagocytosis of microglia. BV-2 cells and primary microglia selected as microglial models in which BV-2 cells were administrated by ATR at different concentrations (0, 4, 8, 16 µM) for 24 h. Results demonstrated ATR dose-dependently increased the expression of ionized calcium binding adapter molecule 1 (Iba-1), indicating that microglia were activated. Microglial phagocytotic activity induced by ATR fluctuated at the different time points, accompanied by fluctuations in membrane receptor MERTK and cytoplasmic lysosomal marker LAMP1 (two markers related to cell phagocytosis). In this period, the expression of iNOS gradually increased. A mechanistic study further demonstrated that the translocation of High Mobility Group Protein-B1 (HMGB1) from nucleus to cytoplasm in the BV-2 and primary microglial cells induced by ATR, and the process showed a positive correlation with phagocytosis activity of BV-2 cells induced by ATR (r = 0.8030, P = 0.05; α = 0.1). ATR was also shown to spur the acetylation of HMGB1 by breaking the balance between acetylase P300 and deacetylase SIRT1. Unexpectedly, the inhibition of acetylating HMGB1 by resveratrol (Res) was effectively retained by HMGB1 in the nucleus, reversed the SIRT1 and MERTK expression, and enhanced the phagocytosis activity in BV-2 cells. Our results suggested that ATR exposure influenced microglial phagocytosis by acetylating HMGB1 further translocated it in the nucleoplasm.

Anxiety-related behavior and associated brain transcriptome and epigenome alterations in adult female zebrafish exposed to atrazine during embryogenesis.

Atrazine often contaminates drinking water sources, exceeding the maximum contaminant level established by the US Environmental Protection Agency at 3 parts per billion (ppb; µg/L). Atrazine is linked to endocrine disruption, neurotoxicity, and cancer, with delayed health effects observed after developmental exposure in line with the developmental origins of health and disease (DOHaD) hypothesis. To test the hypothesis that embryonic atrazine exposure induces delayed neurotoxicity in adult female zebrafish (Danio rerio), embryos were exposed to 0, 0.3, 3, or 30 ppb atrazine during embryogenesis (1-72 h post fertilization (hpf)) and raised to adults with no additional atrazine exposure. Behavioral outcomes were tested through a novel tank test, light-dark box, and open field test and indicated female zebrafish had more anxious phenotypes at 9 months post fertilization (mpf). Female brain transcriptomic analysis at 9 mpf found altered gene expression pathways related to organismal injury and cancer with beta-estradiol and estrogen receptor as top upstream regulators. These results were compared to 9 mpf male and 6 mpf female groups with the same atrazine embryonic exposures and showed differences in specific genes that were altered, but similarities in top molecular pathways. Molecular pathways associated with behavior were observed only in the 6 mpf transcriptomic profiles, suggesting prediction of observed behavioral outcomes at 9 mpf. The expression of genes associated with serotonin neurotransmission was also evaluated at 14 mpf to determine persistence; however, no significant changes were observed. Brain global methylation in 12 mpf zebrafish observed an increased percent 5 mC in females with embryonic 0.3 ppb atrazine exposure. Finally, the body length, body weight, and brain weight were determined at 14 mpf and were altered in all treatment groups. These results indicate that embryonic atrazine exposure does cause delayed neurotoxicity within the DOHaD framework, which is significant given atrazine's presence and persistence in the environment.

Alfalfa's response to atrazine stress and its secreted atrazine metabolites.

Although listed as endocrine disruptor compounds, atrazine (ATZ) is still used in large quantities in agricultural production. Here, alfalfa seedling was cultivated in hydroponic media to investigate the toxic effects of ATZ on alfalfa and accumulation of ATZ in tissues of different plant parts. Alfalfa had a strong upward translocation ability to ATZ. The stress response of alfalfa under ATZ stress was studied using metabolomic and transcriptomic techniques. S-adenosylmethionine, glutathione, 3-mercaptopyruvic acid, ornithine, and aminopropylcadaverine were significantly increased by ATZ in pathways mtr00270 and mtr00480. Several genes of cysteine synthase and spermidine synthase were significantly up-regulated by ATZ induction. They may be markers and genes with potential physiological functions of alfalfa in response to ATZ stress. In addition, using high resolution mass spectrometry, a total of five ATZ metabolites secreted from alfalfa roots were detected. Among them, acetylated deisopropylated ATZ was discovered for the first time. Hydroxylated ATZ and acetylated deethylated ATZ were more readily excreted by the root system. This study not only provides potential genes for the construction of engineering plants to remediate ATZ-contaminated soil, but also provides monitoring objects for the ecological research of ATZ metabolites.

OsBR6ox, a member in the brassinosteroid synthetic pathway facilitates degradation of pesticides in rice through a specific DNA demethylation mechanism.

This manuscript described a comprehensive study on a pesticide degradation factor OsBR6ox that promoted the degradation of pesticides atrazine (ATZ) and acetochlor (ACT) in rice tissues and grains through an epigenetic mechanism. OsBR6ox was transcriptionally induced under ATZ and ACT stress. Genetic disruption of OsBR6ox increased rice sensitivity and led to more accumulation of ATZ and ACT, whereas transgenic rice overexpressing OsBR6ox lines (OEs) showed opposite effects with improved growth and lower ATZ and ACT accumulation in various tissues, including grains. OsBR6ox-mediated detoxification of ATZ and ACT was associated with the increased abundance of brassinolide (one of the brassinosteroids, BRs), a plant growth regulator for stress responses. Some Phase I-II reaction protein genes for pesticide detoxification such as genes encoding laccase, O-methyltransferase and glycosyltransferases were transcriptionally upregulated in OE lines under ATZ and ACT stress. HPLC-Q-TOF-MS/MS analysis revealed an enhanced ATZ/ATC metabolism in OE plants, which removed 1.21-1.49 fold ATZ and 1.31-1.44 fold ACT from the growth medium but accumulated only 83.1-87.1 % (shoot) and 71.7-84.1 % (root) of ATZ and 69.4-83.4 % of ACT of the wild-type. Importantly, an ATZ-responsive demethylated region in the upstream of OsBR6ox was detected. Such an epigenetic modification marker was responsible for the increased OsBR6ox expression and consequent detoxification of ATZ/ACT in rice and environment. Overall, this work uncovered a new model showing that plants utilize two mechanisms to co-regulate the detoxification and metabolism of pesticides in rice and provided a new approach for building up cleaner crops and eliminating residual pesticides in environments.

Atrazine exposure in zebrafish induces aberrant genome-wide methylation.

Atrazine (ATZ) is the second most common agricultural herbicide used in the United States and is an endocrine disrupting chemical (EDC). Developmental exposure to ATZ can lead to significant behavioral and morphological alterations in exposed animals and their progeny suggesting the involvement of an epigenetic mechanism. Specific epigenetic mechanisms responsible for these alterations, however, are yet to be elucidated. In this study, we exposed zebrafish embryos to 0, 0.3, 3, or 30 ppb (µg/L) of ATZ from 1 to 72 h post fertilization (hpf). Chemical exposure was ceased and zebrafish maintained until 9 months post fertilization (mpf), when whole-genome bisulfite sequencing (WGBS) was performed to assess the effects of embryonic ATZ exposure on DNA methylation in female fish brains. The number of differentially methylated genes (DMGs) increased with increasing treatment concentration. DMGs were enriched in neurological pathways with extensive methylation changes consistently observed in neuroendocrine pathways. Specifically, DMGs with methylation changes in promoter regions showed hypomethylation in estrogen receptor signaling and hypermethylation in androgen signaling. DMGs with methylation changes in genebody were primarily enriched for mitochondrion-related pathways associated with healthy aging. Integrated analysis with transcriptomic data at 9 mpf exhibited a similar trend identifying CABLES1 and NDUFA4 as shared targets at all concentrations. We then compared the predicted upstream regulators of transcriptomic changes with DMGs and identified CALML3 as a common upstream regulator at both 0.3 and 30 ppb that exhibit significant methylation changes. Collectively, our study identified long-lasting DNA methylation changes in genome after embryonic ATZ exposure and elucidated potential gene targets whose aberrant methylation features may drive alterations in gene transcription in long-term.

Differential Effects of Atrazine on Chlorophyceae Species and Association with Morphology, Photosynthesis, Chlorophyll Content, and Glutathione-S-Transferase Activity.

Atrazine is a herbicide widely used in the control of weeds in crops such as corn, sugar cane, and sorghum. It is often found in aquatic environments, where it can potentially endanger nontarget organisms such as microalgae. The present study evaluated atrazine toxicity to seven different species of Chlorophyceae and the tolerance of the species to the herbicide was related to morphological, photosynthetic, chlorophyll-a content and the activity of the glutathione-S-transferase enzyme (GST). The comparison of median effect concentration (EC50) values for growth inhibition indicates higher toxicity of atrazine for Pseudopediastrum boryanum and Desmodesmus communis, intermediate toxicity for Ankistrodesmus densus, Chlamydomonas puliminiorfes, and Raphidocelis subcapitata, and lower toxicity for Kirchneriella lunaris and Ankistrodesmus falcatus (EC50: 38, 42, 66, 103, 248, 1004, and 1585 µg L-1 atrazine, respectively). Principal component analysis (PCA) with algal characteristics suggested that the atrazine-sensitive algae P. boryanum and D. communis were positively associated with photosynthetic levels and negatively associated with GST activity and chlorophyll-a concentration. The PCA also suggested that the atrazine-tolerant algae A. falcatus and K. lunaris were positively associated with morphological parameters, where the larger the cell size, the more tolerant. Although it is difficult to associate a single characteristic of algae as the key factor determining the tolerance to atrazine, results presented in this work indicate that the cell area, the photosynthetic parameters (mainly saturating irradiance), chlorophyll-a content, and the biotransformation by GST in combination may be potential predictors for the differential tolerance of Chlorophyceae species to the herbicide. Environ Toxicol Chem 2022;41:1675-1685. © 2022 SETAC.

Integrated metabolomics and transcriptomics analysis reveals new biomarkers and mechanistic insights on atrazine exposures in MCF­7 cells.

Atrazine (ATZ) is a widely used herbicide worldwide and is a long-suspected endocrine-disrupting chemical. However, most endocrine-disrupting toxicity studies on ATZ have been based on animal models and those investigating inner mechanisms have only focused on a few genes. Therefore, the possible link between ATZ and endocrine-disrupting toxicity is still unclear. In this study, multi-omics and molecular biology techniques were used to elucidate the possible molecular mechanisms underlying the effect of ATZ exposure on MCF-7 proliferation at environmentally relevant concentrations. Our study is the first report on ATZ-induced one carbon pool by folate metabolic disorder in MCF-7 cells. A concentration of 1 µM ATZ yielded the highest cell viability and was selected for further mechanistic studies. A total of 34 significantly changed metabolites were identified based on metabolomic analysis, including vitamins, amino acids, fatty acids, and corresponding derivatives. Folate and pyridoxal have potential as biomarkers of ATZ exposure. One carbon pool by folate metabolic pathway was identified based on metabolic pathway analysis of the significantly altered pathways. Moreover, FTCD and MTHFD related to this pathway were further identified based on transcriptomic analysis and protein assays. Folate and different forms of 5,6,7,8-tetrahydrofolate, which participate in purine synthesis and associate with methyl groups (SOPC, arachidonic acid, and L-tryptophan) in one carbon pool by the folate metabolic pathway, potentially promote MCF-7 cell proliferation. These findings on the key metabolites and regulation of the related differentially expressed genes in folate metabolism will shed light on the mechanism of MCF-7 cell proliferation after ATZ exposure. Overall, this study provides new insights into the mechanistic understanding of toxicity caused by endocrine-disrupting chemicals.

Induced Hepatic Glutathione and Metabolomic Alterations Following Mixed Pesticide and Fertilizer Exposures in Juvenile Leopard Frogs (Lithobates sphenocephala).

The increasing use of agrochemicals, alone and in combination, has been implicated as a potential causative factor in the decline of amphibians worldwide. Fertilizers and pesticides are frequently combined into single-use tank mixtures for agricultural applications to decrease costs while meeting the food demands of a growing human population. Limited data are available on the effects of increased nitrogen levels in nontarget species, such as amphibians, and therefore investigating alterations in the nitrogen cycle and its impacts on amphibians needs to be considered in best management practices going forward. The objective of the present study was to elucidate the impact of fertilizer (urea) and herbicide (atrazine and/or alachlor) tank mixtures on the hepatic metabolome of juvenile leopard frogs as well as to investigate alterations in oxidative stress by relating these changes to glutathione (GSH) levels. Herbicide exposure only moderately increased this parameter in amphibians, however, urea alone and in combination with either atrazine or alachlor statistically elevated GSH levels. Interestingly, urea also inhibited pesticide uptake: calculated bioconcentration factors were greatly decreased for atrazine and alachlor when urea was present in the exposure mixture. Metabolomic profiling identified fluxes in hepatic metabolites that are involved in GSH and carbohydrate metabolic processes as well as altered intermediates in the urea cycle. Ultimately, understanding the biological impacts of nitrogenous fertilizers alone and in combination with pesticide exposure will inform best management practices to conserve declining amphibian populations worldwide. Environ Toxicol Chem 2022;41:122-133. © 2021 SETAC.

Prolonged atrazine exposure beginning in utero and adult uterine morphology in mice.

Through drinking water, humans are commonly exposed to atrazine, a herbicide that acts as an endocrine and metabolic disruptor. It interferes with steroidogenesis, including promoting oestrogen production and altering cell metabolism. However, its precise impact on uterine development remains unknown. This study aimed to determine the effect of prolonged atrazine exposure on the uterus. Pregnant mice (n = 5/group) received 5 mg/kg body weight/day atrazine or DMSO in drinking water from gestational day 9.5 until weaning. Offspring continued to be exposed until 3 or 6 months of age (n = 5-9/group), when uteri were collected for morphological and molecular analyses and steroid quantification. Endometrial hyperplasia and leiomyoma were evident in the uteri of atrazine-exposed mice. Uterine oestrogen concentration, oestrogen receptor expression, and localisation were similar between groups, at both ages (P > 0.1). The expression and localisation of key epithelial-to-mesenchymal transition (EMT) genes and proteins, critical for tumourigenesis, remained unchanged between treatments, at both ages (P > 0.1). Hence, oestrogen-mediated changes to established EMT markers do not appear to underlie abnormal uterine morphology evident in atrazine exposure mice. This is the first report of abnormal uterine morphology following prolonged atrazine exposure starting in utero, it is likely that the abnormalities identified would negatively affect female fertility, although mechanisms remain unknown and require further study.

Accumulation, distribution and removal of triazine pesticides by Eichhornia crassipes in water-sediment microcosm.

After application, pesticides remained in the field may contaminate water resources through surface runoff and leaching, posing a threat to aquatic ecosystem. In the current study, the accumulation, translocation, distribution and removal of four triazine pesticides (simazine, atrazine, terbuthylazine and metribuzin) by free floating aquatic plant Eichhornia crassipes (E. crassipes) in water-sediment microcosm were investigated and the removal mechanisms were explored. E. crassipes was exposed to an initial concentration of 50 µg·L-1 and the pesticide levels in water, sediment, roots and shoots of E. crassipes were monitored during 30 days. The results demonstrated that E. crassipes was capable of accumulating triazine pesticides with the bio-concentration factor (BCF) ranging from 0.8 to 18.4. Triazine pesticides were mainly stored in roots, and root accumulation and translocation amount depend on the hydrophobicity of the pesticides. The removal of the pesticides in water were significantly accelerated by the presence of E. crassipes, with the removal efficiency ranging from 66% to 79% after 30 days of treatment. Though phytoaccumulation only constituted 2-18% of the total spiked pesticides in the microcosm, E. crassipes played a vital role in removing simazine, atrazine and metribuzin. However, microbial degradation in sediment was the main pathway for the removal of terbuthylazine in the microcosm. This study demonstrated the potential application of E. crassipes to accelerate removal of contaminants from aquatic environment.

Identification and characterization of serum albumin covalent adduct formed with atrazine by liquid chromatography mass spectrometry.

The present study developed an analytical technique to investigate the possible covalent adduct formation of albumin with the herbicide atrazine, and to characterize the protein modifications in vitro using liquid chromatography separation coupled with high resolution time-of-flight mass spectrometry (LC-TOF-MS). Tandem mass spectrum analysis (MS/MS) with collision induced dissociation (CID) revealed the specific sites of rat, human and bovine serum albumin adduct with atrazine. The formation of b-ion, y-ion series in MS/MS showed a covalent adduct with an addition mass of 179.1 Da located on Cys-34 of serum albumin from rats, human and bovine. This clearly indicated that the chemical group C8H13N5 forms an adduct with Cys-34 despite the sequences differences between of rat, human and bovine serum albumin. To confirm the method reliability, concentration-dependent and time-dependent formation of adducts between serum albumins and atrazine were also investigated. Our results confirmed that atrazine can directly react with Cys-34 of serum albumin and form covalent adducts without prior metabolism.

Biodegradation of atrazine and ligninolytic enzyme production by basidiomycete strains.

BACKGROUND: Atrazine is one of the most widespread chlorinated herbicides, leaving large bulks in soils and groundwater. The biodegradation of atrazine by bacteria is well described, but many aspects of the fungal metabolism of this compound remain unclear. Thus, we investigated the toxicity and degradation of atrazine by 13 rainforest basidiomycete strains. RESULTS: In liquid medium, Pluteus cubensis SXS320, Gloelophyllum striatum MCA7, and Agaricales MCA17 removed 30, 37, and 38%, respectively, of initial 25 mg L- 1 of the herbicide within 20 days. Deficiency of nitrogen drove atrazine degradation by Pluteus cubensis SXS320; this strain removed 30% of atrazine within 20 days in a culture medium with 2.5 mM of N, raising three metabolites; in a medium with 25 mM of N, only 21% of initial atrazine were removed after 40 days, and two metabolites appeared in culture extracts. This is the first report of such different outcomes linked to nitrogen availability during the biodegradation of atrazine by basidiomycetes. The herbicide also induced synthesis and secretion of extracellular laccases by Datronia caperata MCA5, Pycnoporus sanguineus MCA16, and Polyporus tenuiculus MCA11. Laccase levels produced by of P. tenuiculus MCA11 were 13.3-fold superior in the contaminated medium than in control; the possible role of this enzyme on atrazine biodegradation was evaluated, considering the strong induction and the removal of 13.9% of the herbicide in vivo. Although 88% of initial laccase activity remained after 6 h, no evidence of in vitro degradation was observed, even though ABTS was present as mediator. CONCLUSIONS: This study revealed a high potential for atrazine biodegradation among tropical basidiomycete strains. Further investigations, focusing on less explored ligninolytic enzymes and cell-bound mechanisms, could enlighten key aspects of the atrazine fungal metabolism and the role of the nitrogen in the process.

Cytochrome P450 and Glutathione-S-Transferase Activity are Altered Following Environmentally Relevant Atrazine Exposures in Crayfish (Faxoniusvirilis).

The herbicide atrazine is heavily applied in the U.S. Midwest to control broadleaf weeds. It enters local streams and rivers through runoff and seepage, and exposure can affect non-target aquatic organisms, like crayfish. We examined sublethal effects of atrazine on the expression and activity of the detoxification enzymes cytochrome P450 (CYP450) and glutathione-S-transferase (GST) in crayfish. Crayfish were exposed to 0, 10, 40, 80, 100 and 300 ppb atrazine for 1, 2, 4, 7 and 10 days. Their hepatopancreas was collected and CYP450 expression and GST activity was analyzed. Atrazine exposure caused differential expression and activity of CYP450 and GST. CYP450 expression varied over exposure concentrations and time. Further, GST activity significantly increased following a 2 day, 10 ppb exposure to atrazine and a 300 ppb atrazine exposure for all days tested. We found that atrazine detoxification is a dynamic process that changes with the length and intensity of atrazine exposure.

Efficient removal of atrazine by iron-modified biochar loaded Acinetobacter lwoffii DNS32.

In order to efficiently remove commonly used herbicide atrazine in farmland, an iron-modified biochar (FeMBC) was fabricated via chemical co-precipitation of Fe3+ onto corn stalks biochar. The composites of FeMBC and Acinetobacter lwoffii DNS32 (bFeMBC) effectively accelerated the degradation rate of atrazine (100 mg L-1) in inorganic salt culture solution. TEM，XRD，XPS and FTIR were used to study the basic properties of the Materials. FeMBC promoted the formation of bacterial biofilm, -NH functional group on the surface of bacterial extracellular polymers (EPS) and FeMBC could interact with the aromatic ring of atrazine through Hbonding, which were conducive for microbial capture of atrazine. Meanwhile, the pores (2-10 µm) of FeMBC facilitated the passage of the DNS32 strain and the atrazine molecule, which contributed to the efficient capture and degradation of atrazine by DNS32 strain. BFeMBC amendment helped to maintain the bacterial diversity in the atrazine contaminated soil. The increase of rare bacteria (relative abundance of 0.01%-0.05%) richness plays a certain role in stabilizing nutrient cycling, thereby promoting microbial nutrient utilization activities and has the function of pollutant degradation. This may contribute to the digestion of atrazine and its intermediate metabolites，reducing the stress of microbial in atrazine contaminated soil. bFeMBC amendment may be a promising in situ remediation technique for soil atrazine contamination.

Microcosm study of atrazine bioremediation by indigenous microorganisms and cytotoxicity of biodegraded metabolites.

Intensive use of atrazine in agriculture to increase crop productivity has resulted in pollution and consequently deteriorated the environment. Three isolated bacteria, Rhodococcus sp. BCH2 (RB), Bacillus sp. PDK1 (BP1) and Bacillus sp. PDK2 (BP2) possessing capability to degrade atrazine were used in different combinations (RB + BP1, RB + BP2, BP1 + BP2, RB + BP1 + BP2) to prepare a highly effective bacterial consortium which can significantly reduce the toxicity of atrazine. Cytotoxicity tests evaluated by MTT assay on HepG2 indicated significant decrease in the toxicity of atrazine by the consortium RB + BP1 + BP2 due to its effective degradation and formation of simpler and less/nontoxic metabolites compared to other combinations of consortia. A microcosm study was conducted to check the survivability of this consortium (RB + BP1 + BP2) in the presence of atrazine and indigenous soil microflora for four weeks. LC-Q-TOF/MS analysis revealed that RB + BP1 + BP2 could degrade atrazine to various simple metabolites in the microcosm. The cluster analysis of the DGGE patterns of the microcosm of control-soil, soil exposed to atrazine and soil augmented with consortium in the presence of atrazine (1000 mg kg-1) revealed a shift in microbial community of soil. The microbial dynamics studies suggested that the augmented bacteria were well-thrived with natural microflora during four weeks of exposure to atrazine.

Bioaccumulation of pharmaceutically active compounds and endocrine disrupting chemicals in aquatic macrophytes: Results of hydroponic experiments with Echinodorus horemanii and Eichhornia crassipes.

Information regarding the bioaccumulation behaviour of pharmaceutically active compounds (PhACs) and endocrine disrupting chemicals (EDCs) in aquatic plants is limited. The present study involved controlled hydroponic experiments to assess uptake and elimination rate constants (ku, ke), bioconcentration factors (BCFs) and translocation factors (TFs) of several PhACs and EDCs in two aquatic macrophyte species, including one submerged species (Echinodorus horemanii) and one free-floating species (Eichhornia crassipes). The results revealed that the studied compounds are readily taken up in these aquatic plants. While bioconcentration factors (BCFs) and translocation factors (TFs) of the test compounds varied substantially, no discernible relationship with physicochemical properties such as octanol-water distribution coefficient (Dow), membrane-water distribution coefficient (Dmw) and organic carbon-water partition coefficient (Koc). Diphenhydramine and triclosan exhibited the highest degree of uptake and bioaccumulation potential. For example, the whole-plant BCF of triclosan in E. horemanii was 4390L/kg, while the whole-plant BCF of diphenhydramine in E. crassipes was 6130L/kg. BCFs of 17ß-estradiol (E2), 17α-ethinylestradiol (EE2), estrone (E1) and bisphenol A (BPA) were relatively low (2-150L/kg). BCFs were generally higher in free-floating aquatic macrophyte species compared to the submerged species. For the free-floating species, E. crassipes, the majority of PhACs and EDCs were more allocated in roots compared to leaves, with TFs<1. However, some compounds such as caffeine, atrazine, diphenhydramine, E2 and carbamazepine were more allocated in leaf tissue (TFs>1). The study findings may be useful for design and implementation of phytoremediation systems, as well as aid future modeling and risk assessment initiatives for these emerging organic contaminants.

Evaluation of volcanic pumice stone as media in fixed bed sequence batch reactor for atrazine removal from aquatic environments.

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) is a component of S-triazine. Its characteristics make it a pollutant of ecosystems and a probable human carcinogen. The present study evaluated volcanic pumice stone as a suitable media for biological growth and biofilm development in a fixed-bed sequencing batch reactor (FBSBR) for atrazine removal from aquatic environments. The FBSBR was fed with synthetic wastewater containing sucrose and atrazine at four hydraulic retention times to assess biodegradation of atrazine by a microbial consortium for removal from aquatic environments. The maximum efficiency for atrazine and soluble chemical oxygen demand removal were 97.9% and 98.9%, respectively. The results of this research showed that the Stover-Kincannon model was a very good fit (R2 > 99%) for loading atrazine onto the FBSBR. Increasing the initial concentration of atrazine increased the removal efficiency. There was no significant inhibition of the mixed aerobic microbial consortia by the atrazine. Atrazine degradation depended on its initial concentration in the wastewater and the amount of atrazine in the influent. Although this system shows good potential for atrazine removal from aqueous environments, that remaining in the effluent does not yet meet international standards. Further research is required to make this system effective for removal of atrazine from the environment.