食品中农药残留的高通量微生物检测方法研究

目的甲胺磷的微生物高通量定量分析法,并在待检蔬菜样品进行初步的探索。方法以短双歧杆菌LJM-006作为测试菌,选择浓度为0、0.25、0.5、1.0、2.0和4.0 mg/L的甲胺磷标准品溶液20μL加入所述检测管内,37℃厌氧培养8～10 h,分别测定反应管和阴性对照反应管的A500值,B值为样品反应管的A500值,B0值为阴性对照反应管的A500值;以B/B0为纵坐标Y,甲胺磷浓度的对数值为横坐标X,绘制标准曲线,建立甲胺磷含量与B/B0的线性回归方程;以此方法进行模拟食品样品中所含甲胺磷检测,进行准确度、精密度分析。结果双歧杆菌菌株LJM-006对甲胺磷敏感性高,与其他有机磷农药的交叉反应率均小于2%;在0.01～100 mg/L浓度范围内B/B0与甲胺磷浓度对数值的线性关系良好,甲胺磷检测的标准曲线为Y=-24.68X＋66.72,R2为0.9902,IC50=0.25 mg/L,检测下限达到0.1 mg/L,回收率为78.5%～105.7%,批内变异系数≤12%,批间变异系数≤8.2%。结论该方法具有操作简便,具备一定灵敏度和特异性等优点,可作为一种食品中甲胺磷残留筛检方法。

Detection of pesticides residues in food with high-throughput method

Objective To establish microbiological high-throughput method for Methamidophos residue detection,and conduct a preliminary evaluation of the method with vegetables as the test samples.Method Bifidobacterium breve LJM-006 was used as the test microorganism.Each 20 μL of standard methamidophos solutions at the concentrations of 0 mg/L,0.25 mg/L,0.5 mg/L,1 mg/L,2 mg/L,and 4 mg/L was added to the testing tubes,respectively,then the tubes were cultured at 37℃ in anaerobic condition for 8 to 10 hours.The A500 values of the sample reaction tubes(B) and the negative control reaction tubes(B0) were detected to get a standard curve using B/B0 as the vertical ordinate and the logarithm of Methamidophos concentration as the horizontal coordinate;The linear regression equation of Methamidophos content and B/B0 was established to detect the methamidophos contained in simulated food samples;Accuracy and precision analyses were performed.Result The Bifidobacterium breve LJM-006 showed high sensitivity to methanmidophos and a very low cross reaction rate with other organic phosphorus pesticides(<2%).In concentration range of 0.01~100 mg/L B/B0 and methamidophos concentration had a good linear relation.A standard curve was obtained and the regression equation was Y=-24.68X+66.72,and R2 was 0.9902.The 50% inhibition value(IC50) was 0.25 mg/L.The low detection limit was 0.1 mg/L;the recovery rate was 78.5%~105.7%;Intraassay variation coefficient was less than 12%,while interassay variation coefficient less than 8.2%.Conclusion The method is easy to operate,with certain sensitivity and specificity,and can be used as a screening method of Methamidophos Residue in food.