蜡状芽孢杆菌不同菌株降解有机磷农药的特性分析

Analysis of the degradation characteristics of organophosphorus pesticides by different strains of Bacillus cereus

筛选分离降解微生物解决有机磷农药残留给水体和土壤环境带来的污染问题是一项可行的生物修复技术。采用富集培养和定时取样分析有机磷农药残留的方法,分离驯化出三株能够降解有机磷农药的细菌,研究了其形态特征和生理生化特性并对其16SrDNA序列进行了分析,同时比较了三菌株对甲基对硫磷(Methyl-parathion)、毒死蜱(Chlorpyrifos)和三唑磷(Triazophos)的降解特性。结果表明:通过富集培养得到10菌株具有降解甲基对硫磷和毒死蜱的能力,比较确定HY-1、HY-2和HY-4三菌株作为研究对象,经鉴定为蜡状芽孢杆菌(Bacillus cereus)的不同菌株,三菌株在Genbank上的登录号分别为:eu915687、eu915686和eu915688。在甲基对硫磷质量浓度为50 mg·L 1时,三菌株72 h的降解率分别为91.7%、87.7%与92.4%,降解率无显著性差异(P>0.05),当甲基对硫磷质量浓度增加到100 mg·L 1时,三菌株对甲基对硫磷的降解率有所下降,其中HY-2对甲基对硫磷的降解率下降最大达23%,且和其他两菌株有显著性差异(P<0.05)。三菌株72 h对100 mg·L 1毒死蜱的降解率分别达到64.8%、53.7%和56.5%,在不同的毒死蜱初始质量浓度下,HY-1和HY-4两菌株对毒死蜱的降解率无显著性差异(P>0.05),HY-2与HY-1、HY-4两菌株有显著性差异(P<0.05)。三菌株对三唑磷的降解率均较低,其中HY-2对初始质量浓度为100 mg·L 1三唑磷的降解率最高仅为20.7%,其余两菌株对三唑磷的降解率比HY-2低且无显著性差异(P>0.05)。可以得出本研究分离得到的蜡状芽孢杆菌不同菌株对有机磷农药的降解存在多态性。

A feasible way to remediate organophosphorus pesticides contaminated water and soil environment is to screen degrading microorganisms because of its important significance in the biodegradation of pesticide residue. The degrading bacteria were isolated from the wastewater treatment system of the pesticide enterprises by the method of enrichment culturing and analyzing the residue of organophosphorus pesticides at the definite time. The traditional morphology, physiological-biochemical properties as well as 16S rDNA gene sequence analysis were applied to the bacteria classification. Simultaneously, the degrading characteristics of methyl-parathion, chlorpyrifos and triazophos by the bacteria were also studied. The results indicated that 10 bacteria with the ability of degrading methyl-parathion and chlorpyrifos were separated from the liquid enriched culture and HY-1, HY-2 and HY-4 strain were determined as the research object. The three strains were identified as different strains of Bacillus cereus and the Genbank registration numbers were eu915687, eu915686 and eu915688, respectively. The degradation rates of HY-1, HY-2 and HY-4 reached 91.7%, 87.7% and 92.4% within 72 h when the medium contained 50 mg·L-1 of methyl-parathion and the degradation rates among three strains had no significant difference at 0.05 level. When the concentration of methyl-parathion was 100 mg·L-1, the degradation rates declined and the degradation rate by HY-2 dropped by 23% and had significant difference with the other two strains. When the concentration of chlorpyrifos were 100 mg·L-z, the degradation rates of HY-1, HY-2 and HY-4 reached 64.8%, 53.7% and 56.5% within 72 h, respectively. There was no significant difference in the degradation rate when the concentration of chlorpyrifos ranged from 50 mg·L-1 to 200 mg·L-l by HY-1 and HY-4, HY-2 had significant difference with HY-1 and HY-4 at the 0.05 level. The degradation efficiency of 100 mg·L-1 triazophos by three strains was weak, HY-2 reached the highest and was only 20.7%. The degradation rates by the other two strains were lower and had no significant difference at the 0.05 level. The results reflected the diversity of the degradation characteristics of organophosphorus pesticides by different Bacillus cereus strains.