Mammalian cell line-based bioassays for toxicological evaluation of landfill leachate treated by Pseudomonas sp. ISTDF1

Landfill leachate has become a serious environmental concern because of the presence of many hazardous compounds which even at trace levels are a threat to human health and environment. Therefore, it is important to assess the toxicity of leachate generated and discharge it conforming to the safety standards. The present work examined the efficiency of an earlier reported Pseudomonas sp. strain ISTDF1 for detoxification of leachate collected from Okhla landfill site (New Delhi, India). GC-MS analysis performed after treatment showed the removal of compounds like alpha-limonene diepoxide, brominated dioxin-2-one, Bisphenol A, nitromusk, phthalate derivative, and nitrobenzene originally found in untreated leachate. ICP-AES analysis for heavy metals also showed reduction in concentrations of Zn, Cd, Cr, Fe, Ni, and Pb bringing them within the limit of safety discharge. Methyl tetrazolium (MTT) assay for cytotoxicity, alkaline comet assay for genotoxicity, and 7-ethoxyresorufin-O-deethylase (EROD) assay for dioxin-like behavior were carried out in human hepato-carcinoma cell line HepG2 to evaluate the toxic potential of treated and untreated leachates. The bacterium reduced toxicity as shown by 2.5-fold reduction of MTT EC₅₀ value, 7-fold reduction in Olive Tail Moment, and 2.8-fold reduction in EROD induction after 240 h of bacterial treatment.     

Human cell death in relation to DNA damage after exposure to the untreated and biologically treated pharmaceutical wastewater

Among all the pharmaceutical drugs that contaminate the environment, antibiotics occupy an important place due to their high consumption rates in both veterinary and human medicine. The present study examined the ability of Pseudomonas putida to grow on the antibiotic wastewater, currently expanding in Tunisia, containing amoxicillin and cefadroxil. P. putida was very efficient to grow quickly in pharmaceutical wastewater (PW) and in reducing the total dissolved solids to 80.1 %. Cytotoxicity of PW, before and after biodegradation with P. putida mt-2, was evaluated in vitro, using the MTT assay, against four human tumor cell lines such as A549 (lung cell carcinoma), HCT15 (colon cell carcinoma), MCF7 (breast adenocarcinoma), and U373 (glioma cell carcinoma). The PW reduced all human cell lines viability in a dose-dependent manner. This activity was very remarkable against U373 cell line. For this reason, we have tested the genotoxicity of PW using comet assay for quantification of DNA fragmentation. In fact, PW has statistically significant (p?<?0.001) influence on DNA. Indeed, the percentage of genotoxicity was 66.87 and 87.5 %, after 24 and 48 h of treatment, respectively. However, cytotoxicity and genotoxicity decreased strongly when tested the PW obtained after incubation with P. putida mt-2. Our results indicate that P. putida is a promising and improved alternative to treating industrial-scale effluent compared to current chemical treatment procedures used by the industrials.     

2,3,7,8-TCDD-mediated toxicity in peripheral blood mononuclear cells is alleviated by the antioxidants present in <Emphasis Type="Italic">Gelidiella acerosa</Emphasis>: an in vitro study

Seaweeds have been used as a source of traditional medicine worldwide for the treatment of various ailments, mainly due to their ability to quench the free radicals. The present study aims at evaluating the protective effect of methanolic extract of Gelidiella acerosa, an edible red seaweed against 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced toxicity in peripheral blood mononuclear cells (PBMC). For evaluating the protective effect of G. acerosa, PBMC were divided into four groups: vehicle control, TCDD (10 nM), TCDD?+?G. acerosa (300 μg/ml), and G. acerosa alone treated. Scavenging of intracellular reactive oxygen species (ROS) induced by TCDD was assessed by the dichloro-dihydro-fluorescein diacetate (DCFH-DA) method. Alterations at macromolecular level were quantified through lipid peroxidation (LPO) level, protein carbonyl content (PCC) level, and comet assay. The cellular morphology upon TCDD toxicity and G. acerosa treatment was obtained by light microscopy and histopathological studies. The chemical composition present in the methanolic extract of G. acerosa was determined by gas chromatography-mass spectrometry (GC-MS) analysis. The results reveal that 10 nM TCDD caused significant (P?<?0.05) reduction in cell viability (94.10?±?0.99), and treatment with 300 μg/ml extract increased the cell viability (99.24?±?0.69). TCDD treatment resulted in a significant increase in the production of ROS, LPO (114?±?0.09), and PCC (15.13?±?1.53) compared to the control, whereas co-treatment with G. acerosa significantly (P?<?0.05) mitigated the effects. Further, G. acerosa significantly (P?<?0.05) prevented TCDD-induced genotoxicity and cell damage. GC-MS analysis showed the presence of n-hexadecanoic acid (retention time (RT) 13.15), cholesterol (RT 28.80), α-d-glucopyranose, 4-O-α-d-galactopyranosyl (RT 20.01), and azulene (RT 4.20). The findings suggest that G. acerosa has a strong protective ability against TCDD-induced cytotoxicity, oxidative stress, and DNA damage.     

Assessment of DNA damage in Brazilian workers occupationally exposed to pesticides: a study from Central Brazil

We evaluated 41 rural workers occupationally exposed to pesticides and 32 subjects as a control group, using the micronucleus (MN) and the comet assay. For the comet assay, we evaluated the peripheral blood, and for the MN, we sampled cells from the oral epithelium. Damage to DNA was measured by tail length, % DNA in tail (% tail), olive tail moment (OTM), and tail moment (TM). The exposed group presented an 8× increase in MN frequency, when compared to the control group (p <0.05). When we contrasted the MN frequencies between the individuals that use and do not use personal protective equipment, we found a mean of 7.5 MN (57 % variance) and 12.1 MN (130 % variance), respectively. The binucleated cells were 0.04 and 0.005, in the exposed and control groups, respectively, indicating 8× increase in the number of binucleated cells, when comparing the groups (p <0.05). In the comet assay, we demonstrated statistically significant differences in three parameters (% DNA, OTM, and TM) indicating that the rural workers presented high levels of genomic damages. Our results indicate that occupational exposure to pesticides could cause genome damage in somatic cells, representing a potential health risk to Brazilian rural workers that deal constantly with agrochemicals without adequate personal protection equipment.     

Developmental toxicity of PAH mixtures in fish early life stages. Part I: adverse effects in rainbow trout

A new gravel-contact assay using rainbow trout, Oncorhynchus mykiss, embryos was developed to assess the toxicity of polycyclic aromatic hydrocarbons (PAHs) and other hydrophobic compounds. Environmentally realistic exposure conditions were mimicked with a direct exposure of eyed rainbow trout embryos incubated onto chemical-spiked gravels until hatching at 10 °C. Several endpoints were recorded including survival, hatching delay, hatching success, biometry, developmental abnormalities, and DNA damage (comet and micronucleus assays). This bioassay was firstly tested with two model PAHs, fluoranthene and benzo[a]pyrene. Then, the method was applied to compare the toxicity of three PAH complex mixtures characterized by different PAH compositions: a pyrolytic extract from a PAH-contaminated sediment (Seine estuary, France) and two petrogenic extracts from Arabian Light and Erika oils, at two environmental concentrations, 3 and 10 μg g^?1 sum of PAHs. The degree and spectrum of toxicity were different according to the extract considered. Acute effects including embryo mortality and decreased hatching success were observed only for Erika oil extract. Arabian Light and pyrolytic extracts induced mainly sublethal effects including reduced larvae size and hemorrhages. Arabian Light and Erika extracts both induced repairable DNA damage as revealed by the comet assay versus the micronucleus assay. The concentration and proportion of methylphenanthrenes and methylanthracenes appeared to drive the toxicity of the three PAH fractions tested, featuring a toxic gradient as follows: pyrolytic?Arabian Light?Erika. The minimal concentration causing developmental defects was as low as 0.7 μg g^?1 sum of PAHs, indicating the high sensitivity of the assay and validating its use for toxicity assessment of particle-bound pollutants.     

Biodegradation of methyl red by Bacillus sp. strain UN2: decolorization capacity,metabolites characterization,and enzyme analysis

Azo dyes are recalcitrant and refractory pollutants that constitute a significant menace to the environment. The present study is focused on exploring the capability of Bacillus sp. strain UN2 for application in methyl red (MR) degradation. Effects of physicochemical parameters (pH of medium, temperature, initial concentration of dye, and composition of the medium) were studied in detail. The suitable pH and temperature range for MR degradation by strain UN2 were respectively 7.0–9.0 and 30–40 °C, and the optimal pH value and temperature were respectively 8.0 and 35 °C. Mg²⁺ and Mn²⁺ (1 mM) were found to significantly accelerate the MR removal rate, while the enhancement by either Fe³⁺ or Fe²⁺ was slight. Under the optimal degradation conditions, strain UN2 exhibited greater than 98 % degradation of the toxic azo dye MR (100 ppm) within 30 min. Analysis of samples from decolorized culture flasks confirmed biodegradation of MR into two prime metabolites: N,N′dimethyl-p-phenyle-nediamine and 2-aminobenzoic acid. A study of the enzymes responsible for the biodegradation of MR, in the control and cells obtained during (10 min) and after (30 min) degradation, showed a significant increase in the activities of azoreductase, laccase, and NADH-DCIP reductase. Furthermore, a phytotoxicity analysis demonstrated that the germination inhibition was almost eliminated for both the plants Triticum aestivum and Sorghum bicolor by MR metabolites at 100 mg/L concentration, yet the germination inhibition of parent dye was significant. Consequently, the high efficiency of MR degradation enables this strain to be a potential candidate for bioremediation of wastewater containing MR.     

The levels of PAHs and aryl hydrocarbon receptor effects in sediments of Taihu Lake,China

A total of 16 priority polycyclic aromatic hydrocarbons (PAHs) in sediment samples from Taihu Lake were analyzed by instruments, and sediment extracts were assayed for aryl hydrocarbon receptor (AhR)-mediated ethoxyresorufin-o-deethylase (EROD) induction using a rat hepatoma cell line (H4IIE). The cause–effect relationship between the observed EROD activity and chemical concentrations of PAHs was examined. Our results showed that sediment extracts could induce significant AhR effects, and the bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents of raw extracts (TEQ_bios) ranged from 2.7 to 39.8 pg g^?1 dw. Chemical analysis showed that 16 PAHs were all detected in all samples, and their total concentrations (Σ₁₆PAHs) ranged from 179.8 to 1,669.4 ng g^?1 dw. The abundance of sedimentary PAHs in the three regions (Meiliang Bay, Gonghu Bay, and Xukou Bay) showed a decreasing trend from the inflow region to the outflow region. Chemical analysis-derived TEQs (TEQ_cals) contributed by PAHs ranged from 1.6 to 20.7 pg g^?1 dw. The mean contribution rates (CRs) of PAHs to TEQ_bios were 48.9 %. In Meiliang Bay, EROD effects of 60 % samples were caused by PAHs whose CRs were more than 60 %, while in most sampling sites of Gonghu Bay and Xukou Bay, the CRs of PAHs to TEQ_bios were basically below 40 %. In addition, preliminary ecological risk assessment found that PAHs in sediments have very low ecological impact based on the chemical data of PAHs, while the sediments might pose an unacceptable risk to aquatic organisms and their predators based on the data of TEQ_bio. These findings showed that EROD effects of sediment extracts from Taihu Lake were also caused by other compounds, such as dioxins, polychlorinated biphenyls, etc., together.     

Applying Raman spectroscopy to the assessment of the biodegradation of industrial polyurethanes wastes

Polyether-based polyurethanes (PBP) are extremely problematic polymers due to their long persistence in the environment. Moreover, the assessment of PBP biodegradation remains biased due to the inability of conventional methods to determine how their diverse subunits are degraded. To improve our knowledge of PBP biodegradation, we used Raman spectroscopy to identify patterns of PBP biodegradation. Specifically, PBP biodegradation was assessed using a microbial inoculum isolated from an industrial soil in which polyurethanes have been buried for 40 years. During a 28-day biodegradation assay, the PBP biodegradation level reached 27.5 % (w/w), in addition to undergoing profound alteration of the PBP composition as identified by chemical analyses. After microbial degradation, Raman analyses revealed the disappearance of the polymer’s amorphous region, which contains a high polyol content, whereas the isocyanate-rich crystalline regions were preserved. The use of Raman spectroscopy appears to be a particularly useful tool to enhance our assessment of polymer biodegradation.     

Remediation of polycyclic aromatic hydrocarbon and metal-contaminated soil by successive methyl-β-cyclodextrin-enhanced soil washing–microbial augmentation: a laboratory evaluation

Polycyclic aromatic hydrocarbon (PAH) and metal-polluted sites caused by abandoned coking plants are receiving wide attention. To address the associated environmental concerns, innovative remediation technologies are urgently needed. This study was initiated to investigate the feasibility of a cleanup strategy that employed an initial phase, using methyl-β-cyclodextrin (MCD) solution to enhance ex situ soil washing for extracting PAHs and metals simultaneously, followed by the addition of PAH-degrading bacteria (Paracoccus sp. strain HPD-2) and supplemental nutrients to treat the residual soil-bound PAHs. Elevated temperature (50 °C) in combination with ultrasonication (35 kHz, 30 min) at 100 g MCD L^?1 was effective in extracting PAHs and metals to assist soil washing; 93 % of total PAHs, 72 % of Cd, 78 % of Ni, 93 % of Zn, 84 % of Cr, and 68 % of Pb were removed from soil after three successive washing cycles. Treating the residual soil-bound PAHs for 20 weeks led to maximum biodegradation rates of 34, 45, 36, and 32 % of the remaining total PAHs, 3-ring PAHs, 4-ring PAHs, and 5(+6)-ring PAHs after washing procedure, respectively. Based on BIOLOG Ecoplate assay, the combined treatment at least partially restored microbiological functions in the contaminated soil. The ex situ cleanup strategy through MCD-enhanced soil washing followed by microbial augmentation can be effective in remediating PAH and metal-contaminated soil.     

Protective effect of Syzygium cumini against pesticide-induced cardiotoxicity

Pesticide-induced toxicity is a serious issue which has resulted in plethora of diseases all over the world. The organophosphate pesticide malathion has caused many incidents of poisoning such as cardiac manifestations. The present study was designed to evaluate the effect of Syzygium cumini on malathion-induced cardiotoxicity. Dose optimization of malathion and polyphenols such as curcumin, (?)-epicatechin, gallic acid, butylated hydroxyl toluene, etc. was done by MTT cell proliferation assay. Nuclear deformities, ROS production, and integrity of extra cellular matrix components were analyzed by different techniques. S. cumini methanolic pulp extract (MPE), a naturally derived gallic acid-enriched antioxidant was taken to study its effect on malathion-induced toxicity. Nuclear deformities, ROS production, and integrity of extra cellular matrix components were also analyzed. Twenty micrograms per milliliter LD50 dose of malathion was found to cause stress-mediated responses in H9C2 cell line. Among all the polyphenols, gallic acid showed the most significant protection against stress. Gallic acid-enriched methanolic S. cumini pulp extract (MPE) showed 59.76 %?±?0.05, 81.61 %?±?1.37, 73.33 %?±?1.33, 77.19 %?±?2.38 and 64.19 %?±?1.43 maximum inhibition for DPPH, ABTS, NO, H₂O₂ and superoxide ion, respectively, as compared to ethanolic pulp extract and aqueous pulp extract. Our study suggests that S. cumini MPE has the ability to protect against the malathion-mediated oxidative stress in cardiac myocytes.     

Cytotoxicity,genotoxicity and oxidative stress of malachite green on the kidney and gill cell lines of freshwater air breathing fish Channa striata

The cytotoxicity, genotoxicity and oxidative stress of malachite green (MG) was investigated using the fish Channa striata kidney (CSK) and Channa striata gill (CSG) cell lines. Five concentrations ranging from 0.001 to 10 μg mL^?1 were tested in three independent experiments. Cytotoxicity was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Rhodamine 123 and Alamar Blue. The mitochondrial changes and apoptosis of MG-exposed cells were observed by Rhodamine 123 and acridine orange/ethidium bromide (AO/EB) staining, respectively. In vitro potential DNA damaging effect of MG was tested using comet assay. Mitochondrial damage, apoptosis and DNA fragmentation increased in a concentration-dependent manner. Additionally, DNA electrophoretic mobility experiments were carried out to study the binding effect of MG to double-stranded DNA (dsDNA) of cells. DNA shift mobility experiments showed that MG is capable of strongly binding to linear dsDNA causing its degradation. Biochemical parameters such as lipid peroxidation (MDA), catalase (CAT) activity and reduced glutathione (GSH) levels were evaluated after exposure to MG. In CSK and CSG cell lines exposed to MG for 48 h, a significant increase in lipid peroxidation, which might be associated with decreased levels of reduced glutathione and catalase activity in these cell lines (p?相似文献   

Toxicity of atrazine and its bioaccumulation and biodegradation in a green microalga,Chlamydomonas mexicana

This study evaluated the toxicity of herbicide atrazine, along with its bioaccumulation and biodegradation in the green microalga Chlamydomonas mexicana. At low concentration (10 μg L^?1), atrazine had no profound effect on the microalga, while higher concentrations (25, 50, and 100 μg L^?1) imposed toxicity, leading to inhibition of cell growth and chlorophyll a accumulation by 22 %, 33 %, and 36 %, and 13 %, 24 %, and 27 %, respectively. Atrazine 96-h EC50 for C. mexicana was estimated to be 33 μg L^?1. Microalga showed a capability to accumulate atrazine in the cell and to biodegrade the cell-accumulated atrazine resulting in 14–36 % atrazine degradation at 10–100 μg L^?1. Increasing atrazine concentration decreased the total fatty acids (from 102 to 75 mg g^?1) and increased the unsaturated fatty acid content in the microalga. Carbohydrate content increased gradually with the increase in atrazine concentration up to 15 %. This study shows that C. mexicana has the capability to degrade atrazine and can be employed for the remediation of atrazine-contaminated streams.     

Role of cosubstrate and bioaccessibility played in the enhanced anaerobic biodegradation of organochlorine pesticides (OCPs) in a paddy soil by nitrate and methyl-β-cyclodextrin amendments

The present study was conducted to investigate the anaerobic biodegradation potential of biostimulation by nitrate (KNO₃) and methyl-β-cyclodextrin (MCD) addition on an aged organochlorine pesticide (OCP)-contaminated paddy soil. After 180 days of incubation, total OCP biodegradation was highest in soil receiving the addition of nitrate and MCD simultaneously and then followed by nitrate addition, MCD addition, and control. The highest biodegradation of chlordanes, hexachlorocyclohexanes, endosulfans, and total OCPs was 74.3, 63.5, 51.2, and 65.1 %, respectively. Meanwhile, MCD addition significantly increased OCP bioaccessibility (p?<?0.05) evaluated by Tenax TA extraction and a three-compartment model method. Moreover, the addition of nitrate and MCD also obtained the highest values of soil microbial activities, including soil microbial biomass carbon and nitrogen, ATP production, denitrifying bacteria count, and nitrate reductase activity. Such similar trend between OCP biodegradation and soil-denitrifying activities suggests a close relationship between OCP biodegradation and N cycling and the indirect/direct involvement of soil microorganisms, especially denitrifying microorganisms in the anaerobic biodegradation of OCPs.     

Low doses of chlorpyrifos interfere with spermatogenesis of rats through reduction of sex hormones

Use of pesticides results in indirect effects on human health. We aimed to evaluate implications of toxicological effects of subchronic chlorpyrifos exposure on reproductive function in male rats. A total of 48 adult Wistar male rats were separated into four groups (n = 12). Animals were gavaged with 2.5 mg/kg (T1), 5 mg/kg (T2), or 10 mg/kg (T3) body weight of chlorpyrifos (CPF) or distilled water (control) daily for 30 days. Organ weights, epididymal sperm parameters, DNA integrity, sex hormonal (FHS and LH) levels, and alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), and creatinine concentrations were determined on day 31. Another two sets of (four groups/set; n = 10) animals were orally treated with the same doses of CPF, control animal groups were treated with distilled water only for 30 days, and fertility indices and blood plasma acetylcholine esterase (AchE) were determined on day 31. Exposure to CPF resulted in a significant (p < 0.05) decrease in weights of testis and epididymis. An increase in liver weight resulted in reduced sperm counts and sperm motility and an increase in sperm abnormalities. Significant reduction in serum testosterone (p < 0.01), luteinizing hormone (p < 0.05), and follicular stimulating hormone (p < 0.05) levels was evident in animals treated with the highest dose. A significant decrease in the number of viable implantation sites and pups was observed in female rats mated with the T3 (p < 0.01) and T2 (p < 0.05) males. The ALT, AST, GGT, and creatinine contents were significantly increased (p < 0.05 and p < 0.01, respectively) on CPF exposure. A significant (p < 0.01) reduction in blood plasma AchE enzyme was observed with the highest dose. Our results demonstrated that prolonged exposure of CPF induces spermatogenesis damage, possibly through interference with sex hormones and AchE enzyme resulting in reduction of fertility. Therefore, awareness programs on handling CPF (pesticides) to enhance safety warrant minimization of its hazards.     

Bioremediation assessment of diesel–biodiesel-contaminated soil using an alternative bioaugmentation strategy

This study investigated the effectiveness of successive bioaugmentation, conventional bioaugmentation, and biostimulation of biodegradation of B10 in soil. In addition, the structure of the soil microbial community was assessed by polymerase chain reaction-denaturing gradient gel electrophoresis. The consortium was inoculated on the initial and the 11th day of incubation for successive bioaugmentation and only on the initial day for bioaugmentation and conventional bioaugmentation. The experiment was conducted for 32 days. The microbial consortium was identified based on sequencing of 16S rRNA gene and consisted as Pseudomonas aeruginosa, Achromobacter xylosoxidans, and Ochrobactrum intermedium. Nutrient introduction (biostimulation) promoted a positive effect on microbial populations. The results indicate that the edaphic community structure and dynamics were different according to the treatments employed. CO₂ evolution demonstrated no significant difference in soil microbial activity between biostimulation and bioaugmentation treatments. The total petroleum hydrocarbon (TPH) analysis indicated a biodegradation level of 35.7 and 32.2 % for the biostimulation and successive bioaugmentation treatments, respectively. Successive bioaugmentation displayed positive effects on biodegradation, with a substantial reduction in TPH levels.     

Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus

Although silver nanoparticles (NPs) are increasingly used in various consumer products and produced in industrial scale, information on harmful effects of nanosilver to environmentally relevant organisms is still scarce. This paper studies the adverse effects of silver NPs to two aquatic crustaceans, Daphnia magna and Thamnocephalus platyurus. For that, silver NPs were synthesized where Ag is covalently attached to poly(vinylpyrrolidone) (PVP). In parallel, the toxicity of collargol (protein-coated nanosilver) and AgNO₃ was analyzed. Both types of silver NPs were highly toxic to both crustaceans: the EC50 values in artificial freshwater were 15–17 ppb for D. magna and 20–27 ppb for T. platyurus. The natural water (five different waters with dissolved organic carbon from 5 to 35 mg C/L were studied) mitigated the toxic effect of studied silver compounds up to 8-fold compared with artificial freshwater. The toxicity of silver NPs in all test media was up to 10-fold lower than that of soluble silver salt, AgNO₃. The pattern of the toxic response of both crustacean species to the silver compounds was almost similar in artificial freshwater and in natural waters. The chronic 21-day toxicity of silver NPs to D. magna in natural water was at the part-per-billion level, and adult mortality was more sensitive toxicity test endpoint than the reproduction (the number of offspring per adult).     

Biodegradation of imidacloprid in liquid media by an isolated wastewater fungus Aspergillus terreus YESM3

In the present study, a new fungal strain capable of imidacloprid degradation was isolated from agricultural wastewater drain. The fungal strain of YESM3 was identified as Aspergillus terreus based on ITS1-5.8S rDNA-ITS2 gene sequence by PCR amplification of a 500 bp sequence. Screening of A. terreus YESM3 to the insecticide imidacloprid tolerance was achieved by growing fungus in Czapek Dox agar for 6 days at 28°C. High values (1.13 and 0.94 cm cm^?1) of tolerance index (TI) were recorded at 25 and 50 mg L^?1 of imidacloprid, respectively in the presence and absence of sucrose. However, at 400 mg L^?1 the fungus did not grow. Effects of the imidacloprid concentration, pH, and inoculum size on the biodegradation percentage were tested using Box–Behnken statistical design and the biodegradation was monitored by HPLC analysis at different time intervals. Box–Behnken results indicated that optimal conditions for biodegradation were at pH 4 and two fungal discs (10 mm diameter) in the presence of 61.2 mg L^?1 of imidacloprid. A. terreus YESM3 strain was capable of degrading 85% of imidacloprid 25 mg L^?1 in Czapek Dox broth medium at pH 4 and 28°C for 6 days under static conditions. In addition, after 20 days of inoculation, biodegradation recorded 96.23% of 25 mg L^?1 imidacloprid. Degradation kinetics showed that the imidacloprid followed the first order kinetics with half-life (t₅₀) of 1.532 day. Intermediate product identified as 6-chloronicotinic acid (6CNA) as one of the major metabolites during degradation of imidacloprid by using HPLC. Thus, A. terreus YESM3 showed a potential to reduce pollution by pesticides and toxicity in the effected environment. However, further studies should be conducted to understand the biodegradation mechanism of this pesticide in liquid media.     

Increasing CACNA1C expression in placenta containing high Cd level: an implication of Cd toxicity

Cadmium (Cd) has known to produce many adverse effects on organs including placenta. Many essential transporters are involved in Cd transport pathways such as DMT-1, ZIP as well as L-VDCC. Fourteen pregnant women participated and were divided into two groups: high and low Cd-exposed (H-Cd, L-Cd) groups on the basis of their residential areas, Cd concentrations in the blood (B-Cd), urine (U-Cd), and placenta (P-Cd). The results showed that the B-Cd and U-Cd were significantly increased in H-Cd group (p < 0.05). Interestingly, the P-Cd in H-Cd group was elevated (p < 0.05) and positively related to their B-Cd and U-Cd values (p < 0.05). However, the mean cord blood Cd (C-Cd) concentration in H-Cd group was not significantly increased about 2.5-fold when comparing to L-Cd group. To determine the Cd accumulation in placental tissues, metallothionein-1A (MT-1A) and metallothionein-2A (MT-2A) expressions were used as biomarkers. The results revealed that mean MT-1A and MT-2A mRNAs and MT-1/2 proteins were up-regulated in H-Cd group (p < 0.05). In addition, the Ca channel alpha 1C (CACNA1C) mRNA and protein expressions were noticeably elevated in H-Cd group (p < 0.05). From these findings, we suggested that CACNA1C might be implicated in Cd transport in human placenta.     

A new bioseed for determination of wastewater biodegradability: analysis of the experimental procedure

A new bioassay proposed in the patent P201300029 was applied to a pre-treated wastewater containing a mixture of commercial pesticides to simulate a recalcitrant industrial wastewater in order to determine its biodegradability. The test uses a mixture of standardized inoculum of the lyophilized bacteria Pseudomonas putida with the proper proportion of salts and minerals. The results highlight that biodegradation efficiency can be calculated using a gross parameter (chemical oxygen demand (COD)) which facilitates the biodegradability determination for routine water biodegradability analysis. The same trend was observed throughout the assay with the dehydrated and fresh inoculums, and only a difference of 5 % in biodegradation efficiency (E _f) was observed. The obtained results showed that the P. putida biodegradability assay can be used as a commercial test with a lyophilized inoculum in order to monitor the ready biodegradability of an organic pollutant or a WWTP influent. Moreover, a combination of the BOD₅/COD ratio and the P. putida biodegradability test is an attractive alternative in order to evaluate the biodegradability enhancement in water pre-treated with advanced oxidation processes (AOPs).     

Combination of in vitro bioassays for the determination of cytotoxic and genotoxic potential of wastewater, surface water and drinking water samples

In this study we evaluated genotoxicity and cytotoxicity of native samples of wastewaters (15 samples), surface waters (28 samples) and potable waters (8 samples) with the SOS/umuC assay with Salmonella typhimurium TA1535/pSK1002 and MTT assay with human hepatoma HepG2 cells. The genotoxicity of selected samples was confirmed with the comet assay with HepG2 cells. In the SOS/umuC assay 13 out of the 51 samples were genotoxic: two effluent samples from chemical industry; one sample of wastewater treatment plant effluent; two hospital wastewater samples; three river water samples and four lake water samples. Six samples were cytotoxic for HepG2 cells: both effluent samples of chemical industry, two wastewater treatment plant effluent samples, and two river water samples, however, only the chemical industry effluent samples were genotoxic and cytotoxic, indicating that different contaminants are responsible for genotoxic and toxic effects. Comparing genotoxicity of river and lake water samples with the chemical analytical data of the presence of the residues of pharmaceutical and personal care products (non-steroidal anti-inflammatory drugs, UV filters and disinfectants) in these samples, indicated that the presence of UV filters might be linked to the genotoxicity of these samples. The results showed that the application of the bacterial SOS/umuC assay and mammalian cell assays (MTT and comet assay) with HepG2 cells was suitably sensitive combination of assays to monitor genotoxicity and cytotoxicity of native samples of wastewaters and surface waters. With this study we also confirmed that the toxicity/genotoxicity bioassays should be an integral tool in the evaluation of toxicity of complex wastewaters before the release into environment, as well as for the monitoring of surface water quality, providing data useful in risk assessment.