RESUMO
The goal of this study was to optimize methyl parathion (O,O-dimethyl-O-4-p-nitrophenyl phosphorothioate) degradation using a strain of Escherichia coli DH5α expressing the opd gene. Our results indicate that this strain had lower enzymatic activity compared to the Flavobacterium sp. ATCC 27551 strain from which the opd gene was derived. Both strains were assessed for their ability to degrade methyl parathion (MP) in a mineral salt medium with or without the addition of glucose either as suspended cells or immobilized on tezontle, a volcanic rock. MP was degraded by both strains with similar efficiencies, but immobilized cells degraded MP more efficiently than cells in suspension. However, the viability of E. coli cells was much higher than that of the Flavobacterium sp. We confirmed the decrease in toxicity from the treated effluents through acetylcholinesterase activity tests, indicating the potential of this method for the treatment of solutions containing MP.
Assuntos
Arildialquilfosfatase/genética , Proteínas de Bactérias/genética , Recuperação e Remediação Ambiental/métodos , Escherichia coli/genética , Escherichia coli/metabolismo , Flavobacterium/enzimologia , Metil Paration/metabolismo , Arildialquilfosfatase/metabolismo , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Células Imobilizadas/química , Células Imobilizadas/metabolismo , Escherichia coli/química , Flavobacterium/genética , Expressão GênicaRESUMO
A tezontle-packed up-flow reactor (TPUFR) with an immobilized bacterial consortium for biological treatment of methyl-parathion and tetrachlorvinphos was evaluated. These organophosphate pesticides are widely used in Mexico for insect and mite control, respectively. With the aim of developing a tool for pesticide biodegradation, four flow rates (0.936, 1.41, 2.19, and 3.51 l/h) and four hydraulic residence times (0.313, 0.206, 0.133, and 0.083 h) were evaluated in a TPUFR. In the bioreactor, with an operating time of 8 h and a flow of 0.936 l/h, we obtained 75% efficiency in the removal of methyl-parathion and tetrachlorvinphos. Their adsorptions in the volcanic rock were 9% and 6%, respectively. It was demonstrated that the removal of pesticides was due to the biological activity of the immobilized bacterial consortium. We confirmed the decrease in toxicity in the treated effluent from the bioreactor through the application of acute toxicity tests on Eisenia foetida. Immobilization of a bacterial consortium using tezontle as a support is innovative and an economical tool for the treatment of mixtures of organophosphorus pesticide residues.
Assuntos
Bactérias/metabolismo , Biodegradação Ambiental , Poluição Ambiental/prevenção & controle , Metil Paration/metabolismo , Oligoquetos/efeitos dos fármacos , Praguicidas/metabolismo , Tetraclorvinfos/metabolismo , Adsorção , Animais , Reatores Biológicos , Células Imobilizadas , México , Consórcios Microbianos/fisiologia , Oligoquetos/fisiologia , Porosidade , Erupções VulcânicasRESUMO
Burkholderia cenocepacia is an opportunistic pathogen that belongs to Burkholderia cepacia complex (BCC). Burkholderia cenocepacia strain CEIB S5-2 was isolated from agricultural soils in Morelos, Mexico, and previously has shown its abilities for bioremediation. In this study, we report the draft genome sequence of Burkholderia cenocepacia strain CEIB S5-2.