CHARACTERIZATION OF BACTERIAL ISOLATES (Rhizobium leguminosarum and Bacillus thuringiensis) ABLE TO DEGRADE OF MALATHION AND METHOMYL PESTICIDES . | ||||
| Journal of Agricultural Chemistry and Biotechnology | ||||
| Article 5, Volume 1, Issue 11, November 2010, Page 575-588 PDF (436.87 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jacb.2010.90090 | ||||
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| Author | ||||
| Amina A. Hassan | ||||
| Department of Genetics, Fac. Agric., Zagazig Univ. Egypt | ||||
| Abstract | ||||
| The symbiotic nitrogen fixing soil bacterium, Rhizobium leguminosarum bv. vicieae, is well known for its ability to interact with the leguminous plant Vicia faba. It has, however, not been reported that this species possesses the capability to degrade pesticides that are commonly associated with the agricultural processes. In this study the ability of R.leuminosarum bv.vicieae and the bioinsecticide B.thuringiensis bacteria to degrade malathion and methomyl was investigated. Some mutants were have been isolated. Three mutants of Rhizobia were found to be resistant to malathion up to 7000 ppm(RF12 malr, RZ11 malr and RH11 malr). Bt mutants (Bt3 malr, Bt7 malr and Bt8 malr) were also resistant up to 7000 ppm. Methomyl resistant mutants (RF12 lanr, RZ11 lanr and Bt7 lanr) were resistant up to 10.000 ppm. All these mutants were able to utilize malathion or methomyl as a sole carbon source. The yeast extract was observed to enhance bacterial growth rate in the presence of the two pesticides, Whereas, Cfu/ml was reached up to 9.78 x 1016 in Rhizohium and 9.84 x 1016 in Bt after 10 days of incubation time. Bacterial mutants did not lose the property to grow on media containing 7000 ppm malathion or 10.000 ppm methomyl after acridine orange mediated curing. Gene transfer by conjugation mechanism showed that degradative gene(s) was able to transfer among not only between strains but also between different genera. Transconjugants were able to resist and grow in malathion or methomyl containing media. Some transconjugants were found to be higher response to these pesticides than their parents. It has been suggested that malathion and methomyl degradation gene(s) of Rhizobium leguminosarum bv. vicieae and Bacillus thuringiensis are chromosomal harboring not plasmid genes. | ||||
| Keywords | ||||
| Bt; conjugation; mutants; pesticides; Plasmid curing; Rhizobium | ||||
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