本文研究了裸磁珠对金黄色葡萄球菌吸附效果，优化吸附条件，研究金黄色葡萄球菌和大肠杆菌混合菌液的吸附情况，最终将其应用于牛肉样品中金黄色葡萄球菌的检测。通过实验，优化裸磁珠吸附菌体的最小磁珠用量，最小吸附体积和最短吸附时间，并分析是否满足荧光PCR检测需要。结果表明：裸磁珠对浓度为102~107 cfu/mL金黄色葡萄球菌的吸附率在95%以上，有较好吸附效果；10 mg裸磁珠在5 mL菌液中吸附10 min，从磁珠上提取的DNA浓度和纯度可以满足荧光PCR的检测要求；裸磁珠在混合菌体中吸附到的金黄色葡萄球菌可以被荧光PCR检测出来，裸磁珠在牛肉样品中吸附浓度为102 cfu/mL金黄色葡萄球菌提取的DNA可以被荧光PCR检测出来。因此，裸磁珠可用于食品中金黄色葡萄球菌的富集，满足荧光PCR检测菌体量要求。

The adsorption efficiency of bare magnetic particles for different concentrations of Staphylococcus aureus and for mixed bacteria was studied. And the method was applied to the detection of S. aureus in beef samples. The quantity of beads, the broth volume and the reaction time were optimized for enrichment the bacteria, to examine if the method of Real-Time Fluorescent Quantitative PCR is suitable for measuring the content of bacteria. The results showed that the bare magnetic particles had high adsorption rate to S. aureus in the broth, with the content of 102 ~107 cfu/mL in the culture broth. The adsorption rate was over 95%. The DNA from the bacterium cells enriched by 10mg beads and 5mL culture broth for 10 minutes could be detected by Fluorescent Quantitative PCR. The DNA extracted from S. aureus was detected by Fluorescent Quantitative PCR after enriched by beads in beef broth at the concentration of 102 cfu/mL. Moreover, the DNA extracted from S. aureus was tested after enriched by beads from the mixture broth with Escherichia coli. The method could be used for enrichment and detection of S. aureus in food.

江苏省科技厅社会发展项目（BE2016803）