- A comparative study on degradation of complex malathion organophosphate using of Escherichia coli IES-02 and a novel carboxylesterase
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Malathion organophosphates considered as the major constituent of herbicides, pesticides and insecticides. Extensively used in agricultural, horticultures and for numerous household applications contributes to precedence organic pollutants leading antagonistic effects on human health and environment. Therefore detoxification of malathion from contaminated site is of general interest. Simultaneously it is very emerging to isolated novel indigenous microbial strains from contaminated site with a record of pesticide application. In this study Escherichia coli IES-02 isolated from malathion contaminant effluent and the strain showed maximum efficiency in malathion degradation that utilized it as the sole source of carbon. Carboxylesterase (33.0, 30.0, 28.0 kDa) were purified (1685.71 U/mg) from Escherichia coli IES-02 showed significant results in malathion degradation approximately 81% within 20 min as compared with Escherichia coli IES-02 cells within 4 h (99.0 to 95.0%) into monocarboxylic acid and diacid derivatives. The generation time of Escherichia coli was also observed at 60 min with 0.1 ppm, 68 min with 0.5 ppm, 74.5 min with 2.0 ppm and 91.37 min with 50 ppm of malathion. The degradation rate and transformation metabolites were estimated by Gas Chromatography-Mass Spectrometry respectively. Malathion metabolites pathway proposed in this study which revealed the potential application against lethal environmental pollution.
- Sirajuddin, Sadia,Khan, Moazzam Ali,Qader, Shah Ali Ul,Iqbal, Sajid,Sattar, Hafsa,Ansari, Asma
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- Molecular cloning, purification, and biochemical characterization of a novel pyrethroid-hydrolyzing esterase from Klebsiella sp. strain ZD112
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The gene encoding pyrethroid-hydrolyzing esterase (EstP) from Klebsiella sp. strain ZD112 was cloned into Escherichia coli and sequenced. A sequence analysis of the DNA responsible for the esfP gene revealed an open reading frame of 1914 bp encoding for a protein of 637 amino acid residues. No similarities were found by a database homology search using the nucleotide and deduced amino acid sequences of the esterases and lipases. EstP was heterologously expressed in E. coli and purified. The molecular mass of the native enzyme was approximately 73 kDa as determined by gel filtration. The results of sodium dodecyl sulfate - polyacrylamide gel electrophoresis and the deduced amino acid sequence of EstP indicated molecular masses of 73 and 73.5 kDa, respectively, suggesting that EstP is a monomer. The purified EstP not only degraded many pyrethroid pesticides and the organophosphorus insecticide malathion, but also hydrolyzed ρ-nitrophenyl esters of various fatty acids, indicating that EstP is an esterase with broad substrates. The Km for trans- and cis-permethrin and kcat/Km values indicate that EstP hydrolyzes both these substrates with higher efficiency than the carboxylesterases from resistant insects and mammals. The catalytic activity of EstP was strongly inhibited by Hg2+, Ag+, and ρ-chloromercuribenzoate, whereas a less pronounced effect (3-8% inhibition) was observed in the presence of divalent cations, the chelating agent EDTA, and phenanthroline.
- Wu, Pei C.,Liu, Yu H.,Wang, Zhuo Y.,Zhang, Xiao Y.,Li, He,Liang, Wei Q.,Luo, Na,Hu, Ji M.,Lu, Jia Q.,Luan, Tian G.,Cao, Li X.
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p. 836 - 842
(2007/10/03)
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