久效磷降解菌的分离及其酶促降解特性研究

Isolation of a Monocrotophos-Degrading Bacterial Strain and Characterization of Enzymatic Degradation

从某农药厂废水处理池的污泥中分离到1株久效磷高效降解菌株M-1,经过对其形态特征、生理生化、以及16S rDNA序列分析,该菌株初步鉴定为Paracoccus sp..M-1能以久效磷作为唯一碳源生长,24 h对100 mg.L-1久效磷的降解效率为92.47%.久效磷降解酶定域表达试验表明该酶为胞内酶,组成表达.久效磷酶促降解的最适反应pH为8.0,最适反应温度为25℃;其米氏常数(Km)为0.29μmol.mL-1,最大降解速率(Vmax)为682.12μmol.(min.mg)-1.久效磷降解酶热稳定性差,碱性条件下能够保持较高降解活性.

A monocrotophos [ dimethyl （ E）- 1-2-methylcarbamoylvinylphosphate or MCP ] -degrading strain named as M-1 was isolated from sludge collected from the wastewater treatment pool of a pesticide factory and identified as Paracoccus sp. according to its morphology and biochemical properties and 16S rDNA sequence analysis. Using MCP as a sole carbon source, M-1 was able to degrade MCP（ 100 mg· L^- 1 ） by 92.47% in 24 h. The key enzyme（s） involved in the initial biodegradation of monocrotophos in M-1 was shown to be constitutively expressed cytosolic proteins and showed the greatest activity at pH 8.0 and 25 ℃, with its Michaelis-Mentn＇ s constant （Km） and maximum degradation rate （Vmax） of 0.29μmol· mL^-1 and 682.12μmol· （min· mg）^- 1 respectively. This degrading enzyme（s） was sensitive to high temperature, but kept high activity under alkaline conditions.