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HERO ID
3078280
Reference Type
Journal Article
Title
Biodegradation of chlorpyrifos by Enterobacter strain B-14 and its use in bioremediation of contaminated soils
Author(s)
Singh, BK; Walker, A; Morgan, JAW; Wright, DJ
Year
2004
Is Peer Reviewed?
Yes
Journal
Applied and Environmental Microbiology
ISSN:
0099-2240
EISSN:
1098-5336
Publisher
American Society for Microbiology
Volume
70
Issue
8
Page Numbers
4855-4863
Language
English
PMID
15294824
DOI
10.1128/AEM.70.8.4855-4863.2004
Web of Science Id
WOS:000223290100058
URL
http:///www.asm.org
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Abstract
Six chlorpyrifos-degrading bacteria were isolated from an Australian soil and compared by biochemical and molecular methods. The isolates were indistinguishable, and one (strain B-14) was selected for further analysis. This strain showed greatest similarity to members of the order Enterobacteriales and was closest to members of the Enterobacter asburiae group. The ability of the strain to mineralize chlorpyrifos was investigated under different culture conditions, and the strain utilized chlorpyrifos as the sole source of carbon and phosphorus. Studies with ring or uniformly labeled [(14)C]chlorpyrifos in liquid culture demonstrated that the isolate hydrolyzed chlorpyrifos to diethylthiophospshate (DETP) and 3, 5, 6-trichloro-2-pyridinol, and utilized DETP for growth and energy. The isolate was found to possess mono- and diphosphatase activities along with a phosphotriesterase activity. Addition of other sources of carbon (glucose and succinate) resulted in slowing down of the initial rate of degradation of chlorpyrifos. The isolate degraded the DETP-containing organophosphates parathion, diazinon, coumaphos, and isazofos when provided as the sole source of carbon and phosphorus, but not fenamiphos, fonofos, ethoprop, and cadusafos, which have different side chains. Studies of the molecular basis of degradation suggested that the degrading ability could be polygenic and chromosome based. Further studies revealed that the strain possessed a novel phosphotriesterase enzyme system, as the gene coding for this enzyme had a different sequence from the widely studied organophosphate-degrading gene (opd). The addition of strain B-14 (10(6) cells g(-1)) to soil with a low indigenous population of chlorpyrifos-degrading bacteria treated with 35 mg of chlorpyrifos kg(-1) resulted in a higher degradation rate than was observed in noninoculated soils. These results highlight the potential of this bacterium to be used in the cleanup of contaminated pesticide waste in the environment.
Keywords
Microbiology; Biodegradation; Soil contaminants; Pesticides
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