School Of Environment And Earth Sciences

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    ADVANCES IN MICROBIAL BIODEGRADATION OF CHLORPYRIFOS
    (Jerad Publications,, 2014) M.S., Dhanya
    Chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate) an organophosphate pesticide is one of the most commonly used insecticide, acaricide and termiticide in agriculture, households and public health. The exposure of this moderately hazardous pesticide creates health concerns due to choline esterase inhibition, neurotoxicity, psychological and immunological effects. The microbial bioremediation of chlorpyrifos is a viable option for cleaning up the contaminated sites with its eco-friendliness, high efficiency and cost- effectiveness. Several researchers reported potential bacterial strains like Pseudomonas sp., Arthrobacter sp., Bacillus sp., Klebsiella sp., Serratia marcescens, Enterobacter sp., Stenotrophomonas sp., Sphingomonas sp., Flavobacterium sp. etc., fungal strains such as Phanerochaete chrysosporium, Aspergillus terreus, Verticillium sp., Trichoderma harzianum, etc. and cyanobacteria like Anabaena sp., Aulosira fertilissima, Phormidium valderianum for chlorpyrifos degradation. The microbes capable of producing biosurfactants increase biodegradation efficiency of chlorpyrifos by improving bioavailability of the xenobiotic compound by developing critical micellar concentration. The complete detoxification of the pesticide occurs with those microbes that also degrade its metabolites and avoid its accumulation in the environment. The cloning of mpd gene from chlorpyrifos degrading bacterial strains to Escherichia coli helps in developing its biodegradation capability. This paper focuses on the advancements in chlorpyrifos biodegradation for the efficient onsite remediation of the contaminated environment.
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    Laccase immobilized magnetic iron nanoparticles: Fabrication and its performance evaluation in chlorpyrifos degradation
    (Elsevier Ltd, 2017) Das, A.; Singh, J.; Yogalakshmi, K.N.
    Chlorpyrifos degradation was studied using laccase immobilized on magnetic iron nanoparticles (CENPs). The magnetic iron nanoparticles (MNPs) prepared by co-precipitation method were characterized using Transmission electron microscopy (TEM), Scanning electron microscopy- Energy dispersive spectroscopy (SEM-EDS) and Thermogravimetric analysis (TGA). The size of the nanoparticles ranged between 10 and 15 nm. The MNPs were coated with chitosan, surface modified with carbodiimide (EDAC) immobilized with laccase enzymes. The chlorpyrifos degradation studies were performed in batch studies under constant shaking for a period of 12 h. Results of the study showed that laccase immobilized on magnetic iron nanoparticles were effective in degrading more than 99% chlorpyrifos in 12 h at pH 7 and 60 ?C. In the overall degradation percentage, MNPs contributed to 32.3% of chlorpyrifos removal while ENPs resulted in 58.8% chlorpyrifos degradation. Immobilization of enzyme decreased the overall activity of the free enzyme. The CENPs showed 95% activity after five repeated washing and hence possess good reusability potential. ? 2017 Elsevier Ltd