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Bioavailability of an organophosphorus pesticide, fenamiphos, sorbed on an organo clay
journal contribution
posted on 2003-04-23, 00:00 authored by N Singh, M Megharaj, Will GatesWill Gates, G J Churchman, J Anderson, R S Kookana, R Naidu, Z Chen, P G Slade, N SethunathanHydrolysis of an insecticide/nematicide, fenamiphos [ethyl-3-methyl-4-(methylthio)phenyl-(1-methylethyl)phosphoramidate], immobilized through sorption by cetyltrimethylammonium-exchanged montmorillonite (CTMA-clay) by a soil bacterium, Brevibacterium sp., was examined. X-ray diffraction analysis, infrared spectra, and a negative electrophoretic mobility strongly indicated that fenamiphos was intercalated within the bacterially inaccessible interlayer spaces of CTMA-clay. The bacterium hydrolyzed, within 24 h, 82% of the fenamiphos sorbed by the CTMA-clay complex. There was a concomitant accumulation of hydrolysis product, fenamiphos phenol, in nearly stoichiometric amounts. During the same period, in abiotic (uninoculated) controls, 4.6% of the sorbed insecticide was released into the aqueous phase as compared to 6.0% of the sorbed fenamiphos in another abiotic control where activated carbon, a sink for desorbed fenamiphos, was present. Thus, within 24 h, the bacterium hydrolyzed 77% more fenamiphos sorbed by organo clay than the amounts desorbed in abiotic controls. Such rapid degradation of an intercalated pesticide by a bacterium has not been reported before. Evidence indicated that extracellular enzymes produced by the bacterium rapidly hydrolyzed the nondesorbable fenamiphos, even when the enzyme itself was sorbed. Fenamiphos strongly sorbed to an organo clay appears to be readily available for exceptionally rapid degradation by the bacterium.
History
Journal
Journal of agricultural and food chemistryVolume
51Issue
9Pagination
2653 - 2658Publisher
American Chemical SocietyLocation
Washington, D.C.Publisher DOI
ISSN
0021-8561Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2003, American Chemical SocietyUsage metrics
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AdsorptionAluminum SilicatesBiodegradation, EnvironmentalBiological AvailabilityBrevibacteriumHydrolysisInsecticidesOrganophosphorus CompoundsSpectrophotometry, Infraredfenamiphosorgano claysorptionbioavailabilityScience & TechnologyLife Sciences & BiomedicinePhysical SciencesAgriculture, MultidisciplinaryChemistry, AppliedFood Science & TechnologyAgricultureChemistrySOILDEGRADATIONNAPHTHALENEVERMICULITEMONTMORILLONITEBIODEGRADATIONHYDROCARBONSSMECTITE
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