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Maria Aparecida Marinmorales - One of the best experts on this subject based on the ideXlab platform.
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application of micronucleus test and comet assay to evaluate btex Biodegradation
Chemosphere, 2013Co-Authors: Dânia Elisa Christofoletti Mazzeo, Carlos Emilio Levy, Dejanira De Franceschi De Angelis, Silvia Tamie Matsumoto, Maria Aparecida MarinmoralesAbstract:The BTEX (benzene, toluene, ethylbenzene and xylene) mixture is an environmental pollutant that has a high potential to contaminate water resources, especially groundwater. The bioremediation Process by microorganisms has often been used as a tool for removing BTEX from contaminated sites. The application of biological assays is useful in evaluating the efficiency of bioremediation Processes, besides identifying the toxicity of the original contaminants. It also allows identifying the effects of possible metabolites formed during the Biodegradation Process on test organisms. In this study, we evaluated the genotoxic and mutagenic potential of five different BTEX concentrations in rat hepatoma tissue culture (HTC) cells, using comet and micronucleus assays, before and after Biodegradation. A mutagenic effect was observed for the highest concentration tested and for its respective non-biodegraded concentration. Genotoxicity was significant for all non-biodegraded concentrations and not significant for the biodegraded ones. According to our results, we can state that BTEX is mutagenic at concentrations close to its water solubility, and genotoxic even at lower concentrations, differing from some described results reported for the mixture components, when tested individually. Our results suggest a synergistic effect for the mixture and that the Biodegradation Process is a safe and efficient methodology to be applied at BTEX-contaminated sites.
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btex Biodegradation by bacteria from effluents of petroleum refinery
Web Science, 2010Co-Authors: Dânia Elisa Christofoletti Mazzeo, Carlos Emilio Levy, Dejanira De Franceschi De Angelis, Maria Aparecida MarinmoralesAbstract:Groundwater contamination with benzene, toluene, ethylbenzene and xylene (BTEX) has been increasing, thus requiring an urgent development of methodologies that are able to remove or minimize the damages these compounds can cause to the environment. The Biodegradation Process using microorganisms has been regarded as an efficient technology to treat places contaminated with hydrocarbons, since they are able to biotransform and/or biodegrade target pollutants. To prove the efficiency of this Process, besides chemical analysis, the use of biological assessments has been indicated. This work identified and selected BTEX-biodegrading microorganisms present in effluents from petroleum refinery, and evaluated the efficiency of microorganism Biodegradation Process for reducing genotoxic and mutagenic BTEX damage through two test-systems: Allium cepa and hepatoma tissue culture (HTC) cells. Five different non-biodegraded BTEX concentrations were evaluated in relation to biodegraded concentrations. The Biodegradation Process was performed in a BOD Trak Apparatus (HACH) for 20 days, using microorganisms pre-selected through enrichment. Although the Biodegradation usually occurs by a consortium of different microorganisms, the consortium in this study was composed exclusively of five bacteria species and the bacteria Pseudomonas putida was held responsible for the BTEX Biodegradation. The chemical analyses showed that BTEX was reduced in the biodegraded concentrations. The results obtained with genotoxicity assays, carried out with both A. cepa and HTC cells, showed that the Biodegradation Process was able to decrease the genotoxic damages of BTEX. By mutagenic tests, we observed a decrease in damage only to the A. cepa organism. Although no decrease in mutagenicity was observed for HTC cells, no increase of this effect after the Biodegradation Process was observed either. The application of pre-selected bacteria in Biodegradation Processes can represent a reliable and effective tool in the treatment of water contaminated with BTEX mixture. Therefore, the raw petroleum refinery effluent might be a source of hydrocarbon-biodegrading microorganisms.
Guangling Song - One of the best experts on this subject based on the ideXlab platform.
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control of Biodegradation of biocompatable magnesium alloys
Corrosion Science, 2007Co-Authors: Guangling SongAbstract:By utilising its rapid corrosion reaction and controlling its degradation Process through Zn and Mn alloying, purification and anodization, chemically active magnesium can be developed into a biodegradable biocompatible implant material with a specific Biodegradation Process and tolerable hydrogen evolution rate, which may replace current problematic biodegradable polymers in applications.
Ensieh Esmaeili - One of the best experts on this subject based on the ideXlab platform.
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Biodegradation of low density polyethylene ldpe by mixed culture of lysinibacillus xylanilyticus and aspergillus niger in soil
PLOS ONE, 2013Co-Authors: Atefeh Esmaeili, Ahmad Ali Pourbabaee, Hossein Ali Alikhani, Farzin Shabani, Ensieh EsmaeiliAbstract:In this study, two strains of Aspergillus sp. and Lysinibacillus sp. with remarkable abilities to degrade low-density polyethylene (LDPE) were isolated from landfill soils in Tehran using enrichment culture and screening procedures. The Biodegradation Process was performed for 126 days in soil using UV- and non-UV-irradiated pure LDPE films without pro-oxidant additives in the presence and absence of mixed cultures of selected microorganisms. The Process was monitored by measuring the microbial population, the biomass carbon, pH and respiration in the soil, and the mechanical properties of the films. The carbon dioxide measurements in the soil showed that the Biodegradation in the un-inoculated treatments were slow and were about 7.6% and 8.6% of the mineralisation measured for the non-UV-irradiated and UV-irradiated LDPE, respectively, after 126 days. In contrast, in the presence of the selected microorganisms, Biodegradation was much more efficient and the percentages of Biodegradation were 29.5% and 15.8% for the UV-irradiated and non-UV-irradiated films, respectively. The percentage decrease in the carbonyl index was higher for the UV-irradiated LDPE when the Biodegradation was performed in soil inoculated with the selected microorganisms. The percentage elongation of the films decreased during the Biodegradation Process. The Fourier transform infra-red (FT-IR), x-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine structural, morphological and surface changes on polyethylene. These analyses showed that the selected microorganisms could modify and colonise both types of polyethylene. This study also confirmed the ability of these isolates to utilise virgin polyethylene without pro-oxidant additives and oxidation pretreatment, as the carbon source.
M A Sanroman - One of the best experts on this subject based on the ideXlab platform.
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efficient pahs Biodegradation by a bacterial consortium at flask and bioreactor scale
Bioresource Technology, 2012Co-Authors: F Moscoso, Francisco J Deive, I Teijiz, M A SanromanAbstract:In this work, the Biodegradation of three polycyclic aromatic hydrocarbons (PAHs) such as Phenanthrene (PHE), Pyrene (PYR) and Benzo[a]anthracene (BaA) has been investigated. A bacterial consortium consisting of two strains was used for the first time based on preliminary promising Biodegradation data. They were tentatively identified as Staphylococcus warneri and Bacillus pumilus. Degradation values higher than 85% were obtained for each single PAH when operating at flask scale, whereas minimum levels of 90% of PAHs removal were obtained after just 3 days of cultivation at bioreactor scale. The operation in cometabolic conditions led to maximum levels about 75% and 100% at flask and bioreactor scale, respectively. All the experimental data were analyzed in the light of logistic and Luedeking and Piret type models, with the purpose to better characterize the Biodegradation Process by S. warneri and B. pumilus. Finally, the metabolic pathway followed to degrade each PAH was ascertained.
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assessment of a Process to degrade metal working fluids using pseudomonas stutzeri cect 930 and indigenous microbial consortia
Chemosphere, 2012Co-Authors: F Moscoso, Francisco J Deive, M A Longo, P Villar, R Pena, L Herrero, M A SanromanAbstract:The development of a novel biological Process to treat metal working fluids (MWFs)-containing effluents at bioreactor scale was pursued in this work. The bacteria Pseudomonas stutzeri CECT 930 was investigated for the first time as an alternative agent for MWF degradation. An adequate medium design and mixing and aeration system, as well as an appropriate microorganism proved to be crucial for reaching high levels of degradation by P. stutzeri and by an indigenous consortium (about 70% and 50% of reduction in total petroleum hydrocarbon content in less than 2 wk, respectively). Additionally, as there is no information in literature trying to kinetically characterize an MWF-polluted effluent degradation Process, all the experimental data were fitted to logistic and Luedeking and Piret models, that allowed to elucidate the growth-associated character of the Biodegradation Process.
Kuosheng Chen - One of the best experts on this subject based on the ideXlab platform.
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unsaturated consolidation theory for the prediction of long term municipal solid waste landfill settlement
Waste Management & Research, 2006Co-Authors: Rongher Chen, Kuosheng ChenAbstract:The understanding of long-term landfill settlement is important for landfill design and rehabilitation. However, suitable models that can consider both the mechanical and biodecomposition mechanisms in predicting the long-term landfill settlement are generally not available. In this paper, a model based on unsaturated consolidation theory and considering the Biodegradation Process is introduced to simulate the landfill settlement behaviour. The details of problem formulations and the derivation of the solution for the formulated differential equation of gas pressure are presented. A step-bystep analytical procedure employing this approach for estimating settlement is proposed. The proposed model can generally model the typical features of short-term and long-term behaviour. The proposed model also yields results that are comparable with the field measurements.