有机磷农药广谱降解菌A1A18菌株(Brevundimonas sp.)的筛选、鉴定与降解特性分析

从宁夏有机磷农药污染土壤中筛选对毒死蜱、氧化乐果和水胺硫磷等3种常用有机磷农药残留具有降解能力的菌株,确定其降解能力的代际稳定性及其对土壤中有机磷农药的降解特性。采用选择培养法和牛津杯法筛选目标菌株,依据细菌形态学特征、生理生化反应及分子测序结果进行分类鉴定,气相色谱法检测液体培养环境和土壤中有机磷农药的残留量。结果表明:分离、筛选获得1株有机磷农药广谱降解菌A1A18菌株,鉴定为短波单胞菌属(Brevundimonas sp.);在液体培养环境中,A1A18菌株对毒死蜱、氧化乐果和水胺硫磷3种有机磷农药的降解率分别为45.82%、9.52%和13.96%;经10代培养,确定该菌株对3种有机磷农药的降解能力具有很好的遗传稳定性。在有机磷原药质量分数为1.0 mg·kg~(-1)干土的土壤中施用A1A18菌株,降解菌初始数量密度为0.2×10~8 CFU·g~(-1)干土,施药后第21天,土壤中毒死蜱和水胺硫磷的降解率分别达到88.81%和87.75%,较对照提高16.24%和24.62%;施药后第7天,土壤中氧化乐果降解率达86.19%,较对照提高12.69%。短波单胞菌A1A18菌株能促进土壤中毒死蜱、氧化乐果和水胺硫磷的降解,具有较好的田间应用潜力。

Screening,Identification and Degradation Characteristics of a Broad- spectrum Organophosphorus Pesticide-degrading Bacteria Strain A1A18 (Brevundimonas sp.)

In this paper,the biodegradable strains of chlorpyrifos,folimat and isocarbophos were screened from soils contaminated by organophosphorus pesticide in Ningxia.The intergenerational stability and degradation characteristics of organophosphorus pesticides in soil were determined.Organophosphorus selective culture method and oxford-cup method were used to screen the target strains.The bacteria were classified and identified by morphological characteristics,physiological and biochemical reactions and molecular sequencing.Gas chromatography was used to detect the degradation of organophosphorus pesticides by strains in liquid culture environment and soil,respectively.The results showed that a broad-spectrum biodegradable strain of organophosphorus pesticide Brevundimonas sp.A1A18 was obtained.In liquid culture environment,the degradation rates of three organophosphorus pesticides of strain A1A18 were chlorpyrifos 45.82%,folimat 9.52%,isocarbophos 13.96%.After ten generations of culture,it was determined that the strain had good genetic stability for the degradation of three organophosphorus pesticides.A1A18 strain was applied to test soil with organic phosphorus mass fraction of 1.0 mg·kg^{-1 dry soil.The initial concentration of degradation bacteria was 0.2×108 CFU·g-1 dry soil.The degradation rates of chlorpyrifos and isocarbophos were 88.81% and 87.75% respectively on the 21st day after application,which were 16.24% and 24.62% higher than CK.The degradation rates of folimat was 86.19% on the 7th day after application,which was 12.69% higher than CK.Brevundimonas sp.A1A18 strain can promote the degradation of chlorpyrifos,folimat and isocarbophos in soil,and has good potential for application in the field.}