Isolation, Degradadtion And Phylogenetic Analysis Of Organophosphate Degradative Strains

Pesticides can be classified into six kinds: pesticides, bactericides, herbicides, upgrowth regulators, and parasiticides. Methylparathion (MP, also known as methyl-1605) is a kind of high toxicity organophosphate pesticides and used broadly at present throughout China. Its major intermediate during methylparathion degrading process isρ-nitrophenol (PNP), which is soluble and middling toxicity. Human health could be threatened potentially because both MP and PNP have phenyl ring. At present, MP and PNP degrading bacteria reported are mostly Pseudomonas sp., Flavobacterium, Alcaligenes sp. and so on. Furthermore, those strains can only degrade MP and PNP partially. It is reported firstly here that Arthrobacter sp. can degrade both MP and PNP to small molecule synchronously and effectively.The strains X4, L4, X3 were isolated from polluted wastes of Shandong Huayang Pesticide Chemical Industry Group Co., Ltd. They were cultured with MP and PNP (a kind of intermediate during methylparathion degrading process) and used them as the sole carbon source and decomposed them. They are identified as Arthrobacter sp. by means of a series of tests, and it has visible sphere-pole variable cycle. The degrading ability of X4, L4 and X3 was determined by both gas chromatography (GC) and spectrophotometer, and the degradative rate of X4 for MP at 50mg/L and PNP at 50mg/L is above 99% within 7 h. Moreover, X4 also can degrade other organophosphate pesticides quickly. The degradative rate for methamidophos, chlorpyrifos and carbofuran within 20h is 64%, 54% and 68%, respectively. The degradative rate of L4 for MP at 50mg/L and PNP at 50mg/L within 5h is 85% and 98%, respectively, and the degradative rate of L4 for methamidophos, chlorpyrifos and carbofuran within 20h are 70%, 34% and 38%, respectively. The degradative rate of X3 for PNP at 50mg/L is 99% within 7 h, the degradative rate of X3 for 100mg/L PNP is 98% within 20h. The GenBank accession number of the 16S rDNA sequence of X4 and L4 are DQ202320 and DQ201188, respectively.When study on their growth curve, the three degrading strains were cultured in nutrient broth medium, nutrient broth medium containing...