No abstract

A soil bacterium designated strain JQ-41, capable of growth on fenpropathrin as the sole carbon source and energy source, was isolated from a long-term pyrethroid insecticide-treated orchard. Based on the morphology, physio-biochemical characteristics, and 16S rDNA gene analysis, as well as the G+C content of the genomic DNA, the strain JQ-41 was identified as Pseudomonas aeruginosa. Up to 92.3% of 50 mg l(-1) fenpropathrin was degraded by P. aeruginosa strain at 30°C and pH 7 within 7 days. The kinetic parameters q max, K s, and K i were established to be 1.14 day(-1), 38.41 mg l(-1), and 137.67 mg l(-1), respectively, and the critical inhibitor concentration was determined to be 72.72 mg l(-1). Cell surface hydrophobicity of P. aeruginosa strain was enhanced during growth on fenpropathrin. Three metabolites from fenpropathrin degradation were identified by gas chromatography mass spectrometry, and then a possible degradation pathway was proposed. In addition, this isolate was also able to degrade a wide range of synthetic pyrethroid insecticides including cypermethrin, deltamethrin, bifenthrin, and cyhalothrin with the degradation process following the first-order kinetic model. Taken together, our results provide insights into the kinetics and mechanism of fenpropathrin degradation by P. aeruginosa strain and also highlight its promising potential in bioremediation of pyrethroid-contaminated environment.

1To enhance metal biosorption capacity, magnesium chloride modified Lentinula edodes (MMLE) 2 were prepared by treating Lentinula edodes with the mixture of NaOH, ethanol and MgCl 2. In this 3 study, MMLE was successfully applied for removing Cd(II) and Cu(II) from aqueous solution 4 with a high biosorption capacity of 51.64 ± 0.65 and 59.03 ± 0.64 mg g -1 , respectively, which 5 were higher than many other biosorbents. After pretreatment, the surface of spent Lentinula 6 edodes changed significantly and exposed more metal binding sites. When the initial 7 concentration of heavy metal was 50 mg L -1 and the biosorbent dosage was 5 g L -1 , the maximum 8 uptake of Cu(II) and Cd(II) by MMLE at pH 5.0 and 25 °C was more than one order of magnitude 9 higher than the raw biomass.. The equilibrium biosorption data of Cd(II) and Cu(II) could be well 10 described by Langmuir isotherm model. The experimental data obtained from the biosorption 11 process was successfully correlated with pseudo-second-order kinetics model. The determined 12 thermodynamic parameters indicated that the biosorption process was endothermic and 13 spontaneous. Both physisorption and chemisorption were involved in the biosorption of Cd(II) and 14 Cu(II) onto the surface of MMLE through electrostatic interaction, ion exchange and complex 15 formation. After three biosorption-desorption cycles, the biosorption and recovery efficiency of 16 heavy metals from real industrial wastewater could reached about 90% and 80%, respectively. The 17 results show that MMLE could be an effective and alternative biosorbent for the removal of heavy 18 metals from the real industrial wastewater. 19

No abstract