Browsing by Author "M.S., Dhanya"

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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.
Mutagenic Effect in Vegetables by Pesticides
(Krishi Sanskriti Publications, 2013) Nag, Shilpa; Jain, A.K.; M.S., Dhanya
The advent of pesticides in vegetable crops is to control insects, pathogens and weeds aimed at increasing the crop yield, but the applied pesticides are not fully reaching the target pests. It escapes to environment or accumulates in crops resulting in some deleterious changes. The disturbances were observed in physiological and cytological levels of the affected plants by blocking mitosis and producing mitotic and meiotic chromosome abnormalities. Some pesticides like acetamiprid, carbendazim, chlorpyriphos, cypermethrin, dichlorvos, dicofol, dimethoate, fenvalarate, indoxcarb, mancozeb, monocrotophos, profenophos, quinalphos, zineb etc. proved to be mutagens. Researchers reported abnormalities like chromosomes with inactivated centromeres, isochromosome, picnosis, vagrant, stickiness, bridges, precocious separation and lagging chromosomes, reduction in mitotic index, micronuclei, multipolar cells, sister chromatid exchanges, c- mitosis are common in vegetables. Such abnormalities were observed in kharif vegetables like Lycopersicon esculentum, Capsicum annum, Solanum melongena, Abelmoschus esculentus, Cucumis sativus, Vicia faba, Phaseolus vulgaris and rabi vegetables like Allium cepa, Coriandrum sativum, Raphanus sativus, Solanum tuberosum, Pisum sativum etc. The pesticides act as potent environmental mutagens that possess a threat to cause alterations in genetic makeup in vegetables.
Soil Bacteria in Chlorpyrifos Biodegradation
(Krishi Sanskriti Publications, 2014) M.S., Dhanya
The Chlorpyrifos is a broad spectrum organophosphate insecticide used against various crop pests and household pests. The excessive usage of this moderately hazardous pesticide adds up residues to the environment and become toxic to human and animal health. Biodegradation by the microbes is a viable and ecologically safe option to remediate Chlorpyrifos residues from the contaminated environment. A few microbes have the ability to degrade this pesticide for carbon and energy source. The soil bacterial species under Bacillus and Pseudomonas genera such as B. cereus, B. pumilus, B. subtilis, P. putida, P. stutzeri, P. aeruginosa, etc. have high Chlorpyrifos biodegradation efficiency. Alcaligenes sp, Agrobacterium sp., Enterobacter sp., Klebsiella sp., Serratia sp., Stenotrophomonas sp., Sphingomonas sp., Ralstonia sp., Flavobacterium sp, etc. isolated from soil also reported for having potential for degradation of Chlorpyrifos. The bacteria as isolate or in consortium degraded the pesticide by its enzymatic activities depending on environmental factors. The regular application of the pesticide in the agricultural soil results in increase of resistant bacteria with high degradation potential. The genes from these indigenous bacterial strains act as the gene pools for the development of recombinant microbes with pesticide mineralization property. These soil bacteria have been exploited for the insitu bioremediation and clean up of Chlorpyrifos contaminated soil.