食品基质中不同金黄色葡萄球菌肠毒素基因型表达差异研究

Research on the expression of different staphylococcal enterotoxins genotypes in food matrix

中文关键词:  食物中毒  金黄色葡萄球菌  金黄色葡萄球菌肠毒素  基因表达

英文关键词:food poisoning  Staphylococcus aureus  staphylococcal enterotoxins  gene expression

中文摘要:

      目的 比较研究食品基质中不同金黄色葡萄球菌肠毒素(staphylococcal enterotoxins, SEs)基因型的蛋白表达差异, 为预防金黄色葡萄球菌食物中毒提供参考依据。方法 采用特异性聚合酶链反应方法(polymerase chain reaction, PCR)对食品中分离的金黄色葡萄球菌菌株进行肠毒素基因型检测; 选择sea、seb、sec、sed等基因型阳性菌株, 分别接种于胰酪大豆胨液体培养基(trypticase soy broth, TSB)、牛奶、鸡肉中, 按照GB 4789.10—2016《食品安全国家标准 食品微生物学检验 金黄色葡萄球菌检验方法》酶联免疫吸附试验法(enzyme linked immunosorbent assay, ELISA)定量检测TSB培养基、牛奶和鲜鸡肉中不同金黄色葡萄球菌肠毒素基因型的蛋白表达量。结果 30株金黄色葡萄球菌中检测到14株肠毒素基因型阳性菌株, 所占比例为46.67%, 其中sea基因携带率最高(16.67%), 而seb、sec、sed、seh则各占6.67%。肠毒素A (staphylococcal enterotoxin type A, SEA)在TSB、牛奶、鸡肉3种基质中的平均表达量为7.37 ng/mL, 高于SEB、SEC、SED; 不同基质环境对肠毒素的表达具有一定影响, 如SEA、SEB、SEC、SED在TSB中的表达水平最高, 平均表达量为9.04 ng/mL, 牛奶次之, 鸡肉最低。结论 肠毒素基因型的表达与菌株自身的调控及环境作用密切相关, 本研究对肠毒素的产生机制进行初步了解, 有助于进一步降低食物中毒风险。

英文摘要:

      Objective To study and compare the protein expression of different staphylococcal enterotoxins (SEs) genotypes in food substrates, in order to provide reference basis for the prevention of staphylococcal food poisoning. Methods The enterotoxin genotypes of Staphylococcus aureus isolated from food were detected by specific polymerase chain reaction (PCR), and the sea, seb, sec, sed and other genotypic positive strains were selected, then inoculated into trypticase soy broth medium (TSB), milk and fresh chicken respectively. Protein expression of different staphylococcal enterotoxins genotypes in TSB medium, milk and fresh chicken meat was quantitative determined by enzyme-linked immunosorbent assay (ELISA), according to GB 4789.10—2016 National food safety standard-Food microbiological examination-Staphylococcus aureus. Results 14 strains of enterotoxin positive Staphylococcus aureus were detected among 30 strains accounting for 46.67%, of which the carrying rate of sea genotype was the highest accounting for 16.67%. While seb, sec, sed and seh were accounted for 6.67% respectively. The average expression of SEA in TSB, milk and chicken was 7.37 ng/mL, which was higher than SEB, SEC and SED. The expression of enterotoxins was also influenced by various substrate. The expression level of SEA, SEB, SEC and SED in TSB was the highest, and the average expression was 9.04 ng/mL, milk was the second, and chicken was the lowest. Conclusion The expression of enterotoxin genotypes is closely related to the regulation of strains, and the effects of environment. In this study, a preliminary understanding of the production mechanism of enterotoxins is helpful to reduce the risk of food poisoning.