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Biodegradation of Methyl Parathion by Pseudomonas stutzeri YC-YH1 and Detection of Its Metabolites
Received:May 05, 2015  
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KeyWord:methyl parathion;p-nitrophenol;Pseudomonas stutzeri;biodegradation
Author NameAffiliationE-mail
SHI Yan-hua Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China  
REN Lei Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China  
JIA Yang Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China  
RUTH Nahurira Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China  
YAN Yan-chun Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China yanyanchun@caas.cn 
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Abstract:
      A newly isolated bacterial strain YC-YH1, which could degrade methyl-parathion efficiently, was identified according to 16S rRNA gene analysis in combination with physiological, biochemical and Biolog tests. The present study was focused on its capability of degrading methyl parathion. The metabolites of methyl parathion were identified by HPLC-MS. Changes of methyl parathion and its metabolite concentrations in the inorganic medium were determined by HPLC. The primers of genes involved in the methyl parathion degradation were designed and the target fragments were obtained by gene cloning. The influence of degradation intermediates on the growth of the strain YC-YH1 was examined using filter paper and plate methods. The colonic and microscopic morphologies of the strain YC-YH1 was determined. The 16S rRNA gene sequence showed that YC-YH1 had 98% similarity to Pseudomonas stutzeri. Pseudomonas stutzeri YC-YH1 showed high degradation efficiency for parathion-methyl. p-nitrophenol and dimethyl phosphorothioate were identified as the intermediates. p-nitrophenol concentrations increased along with decrease of methyl parathion concentrations in the inorganic medium. However, p-nitrophenol significantly inhibited the growth of the strain YC-YH1 in the inorganic medium. Methyl parathion hydrolase gene mpd and organophosphorus pesticides hydrolase gene ophC2 were both cloned from the strain YC-YH1. These results suggest that the strain YC-YH1 could efficiently degrade methyl parathion, but the degradation intermediate p-nitrophenol could significantly inhibit the growth of the strain YC-YH1.