[show abstract][hide abstract] ABSTRACT: The present study aims to assess mutual interaction among low-molecular-weight polycyclic aromatic hydrocarbons (LMW PAHs), predominant contamitants at petroleum contaminated sites, in nonionic, anionic and their mixed micelles. Cosolubilization effects were evaluated by the molar solubilization ratio, the micelle-water partition coefficient and the deviation ratio. Two conditions existed: i) naphthalene/phenanthrene and naphthalene/fluorene, with significant different hydrophobicities, showed synergistic effect, a new finding compared to previous observations that no more than one solute’s solubility would increase when two solubilizates coexisted, e.g. solubility of naphthalene and phenanthrene in Triton X-100 was increased by 20.8% and 38.5% when cosolubilized, respectively; ii) phenanthrene/fluorene, with similar hydrophobicity, exhibited inhibitive effect due to competition for the same solubilization sites, i.e. solubility of phenanthrene and fluorene in Triton X-100 was decreased by 36.1% and 6.5% when cosolubilized, respectively. Solubility of PAHs with higher log Kow gained larger enhancement. Synergism was stronger in bisolutes solubilization system where more PAHs could solubilize in the micellar shell region. Solubility inhibition was more intense to PAHs with lower log Kow. The cosolubilization trends were consistent in single and mixed surfactant systems, whereas the enhancing and suppressive extent, on the whole, were weakened and strengthened with increasing mole ratio of anionic surfactant in the mixed micelles because of reduction in micelle size. This study suggested the significance of considering multi-solutes’ interaction to estimate solubilization power of surfactants for selective separation of LMW PAHs from water and soil.
Chemical Engineering Journal 02/2014; 244:522-530. · 3.47 Impact Factor
[show abstract][hide abstract] ABSTRACT: The aim of the present study was to investigate pyrene degradation by a functional strain F14, which was constructed through protoplast fusion between Sphingomonas sp. GY2B and Pseudomonas sp. GP3A. The ability of F14 to degrade pyrene increased from 18% to 46% with the decrease of pyrene concentration from 100 mg L−1 to 15 mg L−1 within 10 days. When pyrene was in binary mixture with phenanthrene or naphthalene, about 42% and 78% of pyrene were biodegraded by F14, respectively, indicating the presence of naphthalene or phenanthrene enhanced pyrene degradation, and the enhanced effect of 2-ring naphthalene was more obvious than that of 3-ring phenanthrene. Detection of metabolites 4, 5-dihydropyrene during pyrene degradation further confirmed the degradation capability of fusion strain F14. The present study showed that fusion strain F14 have a promising application in bioremediation of PAHs contaminated environment.
International Biodeterioration & Biodegradation 01/2014; 87:75–80. · 2.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: A fusant strain F14 with high biodegradation capability of phenanthrene was obtained by protoplast fusion between Sphingomonas sp. GY2B (GenBank DQ139343) and Pseudomonas sp. GP3A (GenBank EU233280). F14 was screened and identified from 39 random fusants by antibiotic tests, scanning electron microscope (SEM) and randomly amplified polymorphic DNA (RAPD). The result of SEM analysis demonstrated that the cell shape of fusant F14 different from parental strains. RAPD analysis of 5 primers generated a total of 70 bands. The genetic similarity indices between F14 and parental strains GY2B and GP3A were 27.9 and 34.6 %, respectively. F14 could rapidly degrade phenanthrene within 24 h, and the degradation efficiency was much better than GY2B and GP3A. GC-MS analysis of metabolites of phenanthrene degradation indicated F14 had a different degradation pathway from GY2B. Furthermore, the fusant strain F14 had a wider adaptation of temperatures (25-36 °C) and pH values (6.5-9.0) than GY2B. The present study indicated that fusant strain F14 could be an effective and environment-friendly bacterial strain for PAHs bioremediation.
MIRCEN Journal of Applied Microbiology and Biotechnology 03/2013; · 1.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: Maize is an economic crop that is also a candidate for use in phytoremediation in low-to-moderately Cd-contaminated soils, because the plant can accumulate high concentration of Cd in parts that are nonedible to humans while accumulating only a low concentration of Cd in the fruit. Maize cultivars CT38 and HZ were planted in field soils contaminated with Cd and nitrilotriacetic acid (NTA) was used to enhance the phytoextractive effect of the maize. Different organs of the plant were analyzed to identify the Cd sinks in the maize. A distinction was made between leaf sheath tissue and leaf lamina tissue. Cd concentrations decreased in the tissues in the following order: sheath > root > lamina > stem > fruit. The addition of NTA increased the amount of Cd absorbed but left the relative distribution of the metal among the plant organs essentially unchanged. The Cd in the fruit of maize was below the Chinese government's permitted concentration in coarse cereals. Therefore, this study shows that it is possible to conduct maize phytoremediation of Cd-contaminated soil while, at the same time, harvesting a crop, for subsequent consumption.
Bioinorganic Chemistry and Applications 01/2013; 2013:959764. · 1.17 Impact Factor
[show abstract][hide abstract] ABSTRACT: Zinc oxide nanoparticles (ZnO NPs) are increasingly recognized for their cytotoxicity, whereas little is known about the toxicity mechanisms of ZnO NPs in human cells. To explore the possible molecular mechanisms for apoptosis induced by ZnO NPs, we investigated the relevant apoptotic signaling in human bronchial epithelial (16HBE) cells. ZnO NPs were found to induce intracellular reactive oxygen species (ROS) generation accompanied with the mitochondrial membrane potential (MMP, deltapsi(m)) reduction in 16HBE cells. Further, the expressions of two key apoptotic trigger regulators were determined by quantitative real time PCR and Western blot analysis. It demonstrated that following the exposure of 16HBE cells to ZnO NPs, both levels of mRNA and protein expression of c-Myc were significantly up-regulated, whereas the expressions of Bcl-2 mRNA and protein were down-regulated. Our results suggested that apoptosis induced by ZnO NPs might primarily involve the regulations of c-Myc and Bcl-2 gene expressions besides decline of MMP in 16HBE cells.
Journal of Biomedical Nanotechnology 08/2012; 8(4):669-75. · 5.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: The fusant strain (F14), which produced by protoplast fusion between Sphingomonas sp. GY2B (GenBank DQ139343) and Pseudomonas sp. GP3A (GenBank EU233280), was tested for phenanthrene biodegradation at 30 °C and pH of 7.0. The kinetics of phenanthrene biodegradation by F14 was investigated over a wide range of initial concentration (15-1,000 mg l(-1)). The rate and the extent of phenanthrene degradation increased with the increase of concentration up to 230 mg l(-1), which indicated negligible inhibition effect at low concentrations. The non-competitive inhibition model was found to be fit for the process. GC-MS analysis showed that biodegradation of phenanthrene by F14 was via dioxygenation at both 1,2- and 3,4-positions and followed by 2-hydroxy-1-naphthoic acid and 1-hydroxy-2-naphthoic acid. The relative intensity of 2-hydroxy-1-naphthoic acid was approximately 3-4 times higher than that of 1-hydroxy-2-naphthoic acid, indicating the 2-hydroxy-1-naphthoic acid was the predominant product in the phenanthrene degradation by fusant strain F14.
Current Microbiology 05/2012; 65(3):225-30. · 1.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this work, the electrochemical behavior of a pyrite–carbon paste electrode in the presence and absence of Acidithiobacillus ferrooxidans was investigated by electrochemical impedance spectroscopy (EIS) in conjunction with X-ray photoelectron spectroscopy (XPS). The EIS responses varied over time in both inoculated and sterile solution, suggesting the change of kinetic processes at the pyrite-solution interface during the leaching process. The pyrite oxidation rate was initially controlled by iron moiety dissolution in both of the systems with and without bacteria, with the formation of intermediate products such as elemental sulfur and polysulfide at the surface of pyrite. In the presence of bacteria, these intermediate products could further be oxidized to SO42-. However, the oxidation of S in the sterile solution was undetectable by EIS measurement. These results were also confirmed by XPS measurements, which showed that the presence of microorganisms was able to remove the elemental sulfur from pyrite surface.
[show abstract][hide abstract] ABSTRACT: Polycyclic aromatic hydrocarbons (PAHs) exhibit toxic properties at low concentrations and several have been listed as priority pollutants to be monitored in industrial effluents, natural waters, soils, and sediments. Now there has been tremendous interest in understanding the fate and transport of PAHs in subsurface environments that are largely microaerobic or anaerobic. Although vast information is available on aerobic biotransformation of PAHs, little is known about anaerobic biotransformation of these contaminants. The anaerobic degradation of PAHs in the sediments of Taihu Lake was simulated under laboratory conditions. The effects of different carbon substrates were evaluated, including glucose, sucrose, potato starch, sodium acetate and humic acid. Microbial biomass and community structure were characterized based on the analysis of phospholipid ester-linked fatty acids (PLFA). Fatty acids ranged from C12 to C20 in carbon chain length, including saturated, monounsaturated, branched, and cyclopropyl fatty acids. The results presented in this study showed that supplement with additional carbon substrates can be used to enhance the degradation of total PAHs concentration in anaerobic sediments. PLFA patterns in the anaerobic sediments added carbon substrates indicated higher microbial biomass, and microbial communities also changed. PLFA analysis proved to be a more sensitive indicator than functional parameters.
Chinese Journal of Geochemistry 01/2006; 25:182-183.
[show abstract][hide abstract] ABSTRACT: The oxidation of tailings in ponds may result in acid rock drainage (ARD) which is believe to be able to contaminate the surrounding environment. This study presents the synthesis of sodium triethylenetetramine-bisdithiocarbamate (DTC-TETA) as a coating for pyrite and tailing surfaces to suppress ARD production at source. DTC-TETA characterizations revealed its structure and two CS2H groups were believed as able to coordinate covalently to the pyrite and metal-sulfide tailing surface to prevent metals leaching. Leaching experiments showed decreased Fe leaching by 99.8% and 98.5% upon pyrite exposure to pH 6.0 and 3.0 solutions, respectively. Column leaching also decreased by >90% for Cu, Zn, Cd, Pb, and Fe metals at pH 6.0 and 3.0 solutions for a period of 30 days in fresh and weathered tailing samples. The probable mechanisms of the passivation of pyrite and tailing samples were also proposed. Unlike most of other coatings, DTC-TETA was covalently coordinated to metals and formed a cross-linked hydrophobic passivating layer on the pyrite or tailing surface to inhibit the release of metals in acidic solutions.