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目的研究金黄色葡萄球菌在草莓中生长情况及与3种肠毒素SEA、SEB、SEC产生的相关性。方法将实验菌株进行肠毒素分型确认后,分别制备10~4 CFU/g(高)、10~2CFU/g(低)两个浓度菌液,采用浸泡方式人工污染到草莓上,分别于8℃、25℃下贮存,贮存过程中参照GB 4789对草莓进行金黄色葡萄球菌计数和金黄色葡萄球菌肠毒素(A-C)检测。结果适宜条件下,无论初始污染程度高低,金黄色葡萄球菌都能在草莓上正常生长代谢并产生肠毒素,特别是SEA的产生较SEB和SEC迅速。其中,25℃贮存条件下,金黄色葡萄球菌累计到10~4 CFU/g以上就可从样品中检测到SEA,累计到10~5 CFU/g以上可以检测到SEC,累计到10~7CFU/g以上可以检测到SEB;8℃贮存条件下,48 h内未检测到肠毒素。结论以草莓作为金黄色葡萄球菌培养基质,获得了金黄色葡萄球菌生长及与3种常见肠毒素产生的相关性,对草莓微生物风险评估及相关标准制订具有参考意义。
Objective To study the growth of Staphylococcus aureus in strawberry and the correlation with three kinds of enterotoxins, SEA, SEB and SEC. Methods After confirming the enterotoxin type of the experimental strains, two concentrations of 10 ~ 4 CFU / g (high) and 10 ~ 2CFU / g (low) bacteria were prepared and inoculated to strawberries by immersion, ℃, storage at 25 ℃, reference to GB 4789 during storage of strawberry S. aureus count and Staphylococcus aureus enterotoxin (AC) detection. Results Under appropriate conditions, Staphylococcus aureus could grow normally on strawberry and produce enterotoxins regardless of the initial pollution level. In particular, SEA was produced more rapidly than SEB and SEC. Among them, SEA could be detected from the sample when Staphylococcus aureus accumulated to above 10 ~ 4 CFU / g under 25 ℃ storage condition, and the SEC could be detected when the total amount reached 10 ~ 5 CFU / g, which reached 10 ~ 7CFU / g or more can detect SEB; 8 ℃ storage conditions, 48 h did not detect enterotoxins. Conclusion Using strawberry as the culture medium of Staphylococcus aureus, the growth of Staphylococcus aureus and its relationship with the production of three kinds of common enterotoxins were obtained. It is of great value to the evaluation of strawberries microbial risk and the development of related standards.