微菌落法快速定量检测食品中细菌总数

RAPID DETECTION OF TOTAL BACTERIAL COUNT IN FOOD BY MICROCOLONY TECHNIQUE

目的以微孔滤膜作载体,结合多媒体彩显显微放大计数系统,建立快速检测食品中细菌总数方法。方法将待测标本1mL接种于微孔滤膜上,以真空泵负压抽滤,取下滤膜将其贴于营养琼脂平板表面,37℃微菌落法培养3～5h,国标法培养48h,沙黄染色,通过显微摄像电脑放大系统进行计数。用微菌落法与国标法分别对6份不同浓度大肠杆菌悬液中大肠杆菌和36份食品中细菌总数进行平行检测。结果微菌落法对6个大肠杆菌菌液测得结果分别为205、100、117、105、160、184cfu.mL-1,国标法测得结果分别为200、110、120、100、150、180cfu.mL-1,两种方法测得的结果差异无显著性(P>0.05)。两种方法对36份食品中细菌总数测得的结果最大相差为20cfu.mL-1,差异无显著性(P>0.05)。结论该法具有快速、准确、简单易操作等优点,适用于现场对食品中的细菌总数进行快速检测。

Objective Using millipore filter membrane to serve as carrier, and multimedia microscopy photograph with magnifying enumeration system to establish a rapid detection method for total bacterial count in food. Methods One mL of food sample was innoculated onto the millipore membrane, filtered by vaceum pump. The membrane was placed on the surface of nutrient agar plate to cultivate at 37 ℃for 3 - 5 h,then was stained with safranine. The total bacterial count was enumerated by multimedia microscopy photograph system. The total bacterial count of 6 E coli suspensions with different concentrations, and 36 food samples were parallely detected with mieroeolony technique at 37℃ for 3 - 5 h as well as GB method at 37℃ for 48 h. Results The total bacterial count of 6 E eoli suspensions with different concentrations by mieroeolony technique were 205,100,117,105,160,184 cfu· mL^-1 respectively. No significant difference was found between the two methods （ P 〉 0.05）. The total bacterial count of 36 food samples by mierocolony technique were also not significantly different from those by GB method（no greater than 20 cfu·mL^-1, P 〉 0.05）. Conclusions The method has the advantages of rapidity, accuracy, low-cost and easy to operate.