X-H Qiu1, W-Q Bai, Q-Z Zhong, M Li, F-Q He, B-T Li. 1. State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China. quixh@ioz.ac.cn
Abstract
AIMS: To isolate and characterize a methyl parathion (MP)-mineralizing bacterium, and to elucidate the degradative pathway of MP and localize the responsible degrading genes. METHODS AND RESULTS: A bacterial strain, designated B2, capable of mineralizing MP was isolated from the MP-polluted soil. Analysis of the 16S rRNA gene sequence and phenotypic analysis suggested that strain B2 had a close relationship with Ochrobactrum anthropi. B2 could totally degrade MP and four metabolites [p-nitrophenol (PNP), 4-nitrocatechol (4-NC), 1,2,4-benzenetriol (BT) and hydroquinone (HQ)] were identified by HPLC and gas chromatography-mass spectrometry analyses. Plasmid curing of strain B2 resulted in the loss of ability of B2 to degrade PNP, but not the ability to hydrolyse MP. CONCLUSIONS: Ochrobactrum sp. B2 can mineralize MP rapidly via PNP, 4-NC, BT and HQ pathway. B2 harbours a plasmid encoding the ability to degrade PNP, while MP-hydrolysing activity is encoded on the bacterial chromosome. SIGNIFICANCE AND IMPACT OF THE STUDY: This new bacterial strain (B2) capable of mineralizing MP will be useful in a pure-culture remediation process of organophosphate pesticides and their metabolites such as nitroaromatics.
AIMS: To isolate and characterize a methyl parathion (MP)-mineralizing bacterium, and to elucidate the degradative pathway of MP and localize the responsible degrading genes. METHODS AND RESULTS: A bacterial strain, designated B2, capable of mineralizing MP was isolated from the MP-polluted soil. Analysis of the 16S rRNA gene sequence and phenotypic analysis suggested that strain B2 had a close relationship with Ochrobactrum anthropi. B2 could totally degrade MP and four metabolites [p-nitrophenol (PNP), 4-nitrocatechol (4-NC), 1,2,4-benzenetriol (BT) and hydroquinone (HQ)] were identified by HPLC and gas chromatography-mass spectrometry analyses. Plasmid curing of strain B2 resulted in the loss of ability of B2 to degrade PNP, but not the ability to hydrolyse MP. CONCLUSIONS:Ochrobactrum sp. B2 can mineralize MP rapidly via PNP, 4-NC, BT and HQ pathway. B2 harbours a plasmid encoding the ability to degrade PNP, while MP-hydrolysing activity is encoded on the bacterial chromosome. SIGNIFICANCE AND IMPACT OF THE STUDY: This new bacterial strain (B2) capable of mineralizing MP will be useful in a pure-culture remediation process of organophosphate pesticides and their metabolites such as nitroaromatics.