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Resultados 1421-1430 de 1,955
Batch and continuous biodegradation of Amaranth in plain distilled water by P. aeruginosa BCH and toxicological scrutiny using oxidative stress studies Texto completo
2013
Jadhav, Shekhar B. | Patil, Nilambari S. | Watharkar, Anuprita D. | Apine, Onkar A. | Jadhav, Jyoti P.
Bacterium Pseudomonas aeruginosa BCH was able to degrade naphthylaminesulfonic azo dye Amaranth in plain distilled water within 6 h at 50 mg l⁻¹ dye concentration. Studies were carried out to find the optimum physical conditions and which came out to be pH 7 and temperature 30 °C. Amaranth could also be decolorized at concentration 500 mg l⁻¹. Presence of Zn and Hg ions could strongly slow down the decolorization process, whereas decolorization progressed rapidly in presence of Mn. Decolorization rate was increased with increasing cell mass. Induction in intracellular and extracellular activities of tyrosinase and NADH-DCIP reductase along with intracellular laccase and veratryl alcohol oxidase indicated their co-ordinate action during dye biodegradation. Up-flow bioreactor studies with alginate immobilized cells proved the capability of strain to degrade Amaranth in continuous process at 20 ml h⁻¹ flow rate. Various analytical studies viz.—HPLC, HPTLC, and FTIR gave the confirmation that decolorization was due to biodegradation. From GC-MS analysis, various metabolites were detected, and possible degradation pathway was predicted. Toxicity studies carried out with Allium cepa L. through the assessment of various antioxidant enzymes viz. sulphur oxide dismutase, guaiacol peroxidase, and catalase along with estimation of lipid peroxidation and protein oxidation levels conclusively demonstrated that oxidative stress was generated by Amaranth.
Mostrar más [+] Menos [-]Low-cost adsorbents from bio-waste for the removal of dyes from aqueous solution Texto completo
2013
Manoj Kumar Reddy, P. | Mahammadunnisa, Sk | Ramaraju, B. | Sreedhar, B. | Subrahmanyaṃ, Cuncu
Activated carbons (ACs) were developed from bio-waste materials like rice husk and peanut shell (PS) by various physicochemical activation methods. PS char digested in nitric acid followed by treatment at 673 K resulted in high surface area up to ∼585 m²/g. The novelty of the present study is the identification of oxygen functional groups formed on the surface of activated carbons by infrared and X-ray photoelectron spectroscopy and quantification by using temperature programmed decomposition (TPD). Typical TPD data indicated that each activation method may lead to varying amounts of acidic and basic functional groups on the surface of the adsorbent, which may be a crucial factor in determining the adsorption capacity. It was shown that ACs developed during the present study are good adsorbents, especially for the removal of a model textile dye methylene blue (MB) from aqueous solution. As MB is a basic dye, H₂O₂-treated rice husk showed the best adsorption capacity, which is in agreement with the acidic groups present on the surface. Removal of the dye followed Langmuir isotherm model, whereas MB adsorption on ACs followed pseudo-second-order kinetics.
Mostrar más [+] Menos [-]Semen quality of environmentally exposed human population: the toxicological consequence Texto completo
2013
Pant, Niraj | Pant, A. B. | Chaturvedi, P. K. | Shukla, M. | Mathur, N. | Gupta, Y. K. | Saxena, D. K.
Human data on the relationship of semen quality with pesticide and metals are mostly inconsistent. The purpose of the study is to confirm the toxicity of organochlorine pesticide β- and γ-hexachlorocyclohexane (HCH), DDE and DDD, and metals lead or cadmium on sperm motility in epidemiological study among fertile and infertile men and to determine whether in vivo and in vitro results are in the same direction. Semen analysis and estimation of the toxicants were done in 60 fertile and 150 infertile men. In the in vitro studies, sperm were exposed to the highest levels of these toxicants found in vivo, as well as five and ten times higher, and to the mixture of all compounds. The study assesses sperm viability and motility for a period ranging between 30 min and 96 h. Epidemiological data showed an inverse correlation of toxicant with sperm motility. In vitro study showed that γ-HCH and lead after 12 h, cadmium after 8 h, and coexposure to toxicants after 6 h of exposure caused significant concentration- and duration-dependent decline in sperm motility. Data of in vitro study were concurrent with epidemiological finding that might be useful in establishing the possible association between exposure and effect of these selected pollutants on sperm motility.
Mostrar más [+] Menos [-]Can conservation of single surrogate species protect co-occurring species? Texto completo
2013
Kang, Dongwei | Yang, Hongwei | Li, Junqing | Chen, Youping
Conservation of surrogate species is expected to benefit co-occurring species with similar distributions that share the same habitat, yet the usefulness of this approach to protect nontarget species has been extensively challenged. In this study, we aimed to assess whether co-occurring species could be afforded protection under the conservation of two proposed surrogate species, the giant panda and the takin. We undertook a thorough study on the habitat requirements of these two endangered species, based on the analysis of their habitat preferences. The results revealed that the giant panda exhibits more specialized habitat preferences than does the takin and that habitat separation between these species mainly reflected differences in their dietary requirements and preferences. We suggest that these differences might facilitate their coexistence in sympatric areas. Meanwhile, results of a discriminant function analysis showed that protection of giant pandas would protect 82.1 % of the panda's habitat, but only 25.4 % of the takin's habitat and just 57.0 % of the joint habitats of these species. Importantly, our results also showed that a joint surrogate species approach to conservation would protect 86.9 % of the panda's habitat, 53.7 % of the takin's habitat, and 72.2 % of the joint habitats of these species. This is a higher degree of habitat protection than the single surrogate conservation of pandas. We conclude that the joint surrogate species approach should be adopted to improve biodiversity conservation.
Mostrar más [+] Menos [-]Evaluation of the optimum volatile organic compounds control strategy considering the formation of ozone and secondary organic aerosol in Seoul, Korea Texto completo
2013
Shin, H. J. | Kim, J. C. | Lee, Seunghun J. | Kim, Y. P.
The characteristics of volatile organic compounds (VOCs) and their annual trends in Seoul, Korea were investigated, with their optimal control strategy suggested. The annual concentration of VOCs (96.2–121.1 ppbC) has shown a decreasing trend from 2004 to 2008, suggesting the control strategy via the “Special Measures for Metropolitan Air Quality Improvement,” which was implemented in 2005, has been successful. The contributions of individual VOC to the production of ambient ozone and secondary organic aerosol (SOA) are discussed to assess the adequacy of current control strategies. The contribution of aromatics (C6–C10) to the production of ozone accounted for 38.7–46.3 % of the total ozone production, followed by low carbon alkanes (C2–C6) (27.0–35.9 %). The total SOA formation potential of VOCs was found to range from 2.5 to 3.5 μg m⁻³, mainly as a result of aromatics (C6–C10) (over 85 %). Considering the contributions from ozone and SOA production, it was concluded that solvent use was the most important emission source, followed by vehicle exhaust emissions. Thus, the current emission control strategy focused on these two emission sources is appropriate to reduce the VOCs related pollution level of the Seoul Metropolitan Region. Still, an additional control strategy, such as controlling the emissions from meat cooking, which is an emission source of high carbon alkanes (C7–C10), needs to be considered to further reduce the VOCs related pollution level in Seoul.
Mostrar más [+] Menos [-]Evaluation of the individuality of white rot macro fungus for the decolorization of synthetic dye Texto completo
2013
Pandey, Priyanka | Singh, Ram Praksh | Singh, Kailash Nath | Manisankar, Paramasivam
INTRODUCTION: A biosorbent was developed by simple dried Agaricus bisporus (SDAB) and effectively used for the biosorption of cationic dyes, Crystal Violet and Brilliant Green. MATERIALS AND METHODS: For the evaluation of the biosorbent system, all the batch equilibrium parameters like pH, biomass dose, contact time, and temperature were optimized to determine the decolorization efficiency of the biosorbent. The maximum yields of dye removal were achieved at pH 4.0 for Crystal Violet (CV) and pH 5.0 for Brilliant Green (BG), which are closer to their natural pH also. RESULT AND DISCUSSION: Equilibrium was established at 60 and 40 min for CV and BG, respectively. Pseudo first-order, pseudo second-order, and intraparticle-diffusion kinetic models were studied at different temperatures. Isotherm models such as Freundlich, Langmuir, and Dubinin–Radushkevich were also studied. Biosorption processes were successfully described by Langmuir isotherm model and the pseudo second-order kinetic model. CONCLUSIONS: The biosorption capacity of A. bisporus over CV and BG were found as 21.74 and 12.16 mg gm⁻¹. Thermodynamic parameters indicated that the CV and BG dye adsorption onto A. bisporus is spontaneous and exothermic in the single and ternary systems. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used for the surface morphology, crystalline structure of biosorbent, and dye–biosorbent interaction, respectively. This analysis of the biosorption data confirmed that these biosorption processes are ecofriendly and economical. Thus, this biomass system may be useful for the removal of contaminating cationic dyes.
Mostrar más [+] Menos [-]Seasonal dynamics of harmful algae in outer Oslofjorden monitored by microarray, qPCR, and microscopy Texto completo
2013
Dittami, Simon M. | Hostyeva, Vladyslava | Egge, Elianne Sirnæs | Kegel, Jessica U. | Eikrem, Wenche | Edvardsen, Bente
Monitoring of marine microalgae is important to predict and manage harmful algal blooms. Microarray Detection of Toxic ALgae (MIDTAL) is an FP7-funded EU project aiming to establish a multi-species microarray as a tool to aid monitoring agencies. We tested the suitability of different prototype versions of the MIDTAL microarray for the monthly monitoring of a sampling station in outer Oslofjorden during a 1-year period. Microarray data from two different versions of the MIDTAL chip were compared to results from cell counts (several species) and quantitative real-time PCR (qPCR; only Pseudochattonella spp.). While results from generation 2.5 microarrays exhibited a high number of false positive signals, generation 3.3 microarray data generally correlated with microscopy and qPCR data, with three important limitations: (1) Pseudo-nitzschia cells were not reliably detected, possibly because cells were not sufficiently retained during filtration or lysed during the extraction, and because of low sensitivity of the probes; (2) in the case of samples with high concentrations of non-target species, the sensitivity of the arrays was decreased; (3) one occurrence of Alexandrium pseudogonyaulax was not detected due to a 1-bp mismatch with the genus probe represented on the microarray. In spite of these shortcomings our data demonstrate the overall progress made and the potential of the MIDTAL array. The case of Pseudochattonella — where two morphologically similar species impossible to separate by light microscopy were distinguished — in particular, underlines the added value of molecular methods such as microarrays in routine phytoplankton monitoring.
Mostrar más [+] Menos [-]Human cell death in relation to DNA damage after exposure to the untreated and biologically treated pharmaceutical wastewater Texto completo
2013
Krifa, Mounira | Dellai, Afef | Bouhlel, Ines | Robert, Jacque | Cherif, Ameur | Barillier, Daniel | Mosrati, Ridha | Chekir-Ghedira, Leila | Ben Mansour, Hedi
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.
Mostrar más [+] Menos [-]Mechanism of aflatoxin uptake in roots of intact groundnut (Arachis hypogaea L.) seedlings Texto completo
2013
Snigdha, M. | Hariprasad, P. | Venkateswaran, G.
Aflatoxins are one of the most potent toxic substances that occur naturally, which enter agricultural soils through the growth of aflatoxigenic fungi in rhizhosphere and nonrhizhosphere soils. Though several reports regarding the uptake of aflatoxin by plants are available, the mechanism of aflatoxin uptake remains unknown. This study characterized the aflatoxin uptake mechanism by in vitro hydroponic experiments under variable conditions. The uptake reached saturation after 48 h of incubation for AFB1 and B2 and 60 h for AFG1 and G2. A linear increase in uptake with increasing aflatoxin concentrations was observed, and it fits both linear and nonlinear regression. AFB1 uptake was directly proportional to transpiration rate, and blocking aquaporin activity using mercuric chloride revealed its involvement in the uptake. None of the metabolic inhibitors used to block active transport had any effect on aflatoxin uptake except for sodium azide. From the present study, it could be concluded that aflatoxin uptake by groundnut roots followed mainly a passive way and is facilitated through aquaporins. The involvement of active component should be studied in detail.
Mostrar más [+] Menos [-]Short-chain chlorinated paraffins (SCCPs) in surface soil from a background area in China: occurrence, distribution, and congener profiles Texto completo
2013
Wang, Xue-Tong | Zhang, Yuan | Miao, Yi | Ma, Ling-Ling | Li, Yuan-Cheng | Chang, Yue-Ya | Wu, Ming-Hong
Short-chain chlorinated paraffins (SCCPs) are extremely complex technical mixtures of polychlorinated n-alkanes with carbon chain lengths from C₁₀to C₁₃and chlorine content between 49 and 70 %. SCCPs are under consideration for inclusion in the Stockholm Convention on persistent organic pollutants. SCCPs have been used extensively in industrial production, but little is known about the pollution level in soil environment in China. In this study, levels and distribution of SCCPs in soil samples from Chongming Island were analyzed. Concentrations of total SCCPs in soil samples ranged from 0.42 to 420 ng g⁻¹, with a median of 9.6 ng g⁻¹. The ubiquitous occurrence of SCCPs in Chongming Island implied that long-range atmospheric transport and soil–air exchange may be the most important pathways for SCCP contamination in the background area. The localized SCCP contamination could be derived from an unidentified source. Hierarchical cluster analysis indicated that C₁₃- and C₁₁-congeners were predominant in most soils and C₁₀- and C₁₂-congeners dominated in the remaining soils. Cl₇- and Cl₈-congeners were on the average the most dominant chlorine congeners in nearly all soils. Principal component analysis suggested that the separation of even and odd carbon chain congeners occurred during long-range atmospheric transport and aging in soil in the study area.
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