金黄色葡萄球菌肠毒素A、B、C在草莓中 表达的研究

Study of staphylococcal enterotoxins A, B, and C expression on strawberry

中文关键词:  草莓  金黄色葡萄球菌  肠毒素

英文关键词:strawberry  Staphylococcus aureus  staphylococcal enterotoxins

中文摘要:

      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104 CFU/g (高)、102 CFU/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104 CFU/g以上就可从样品中检测到SEA, 累计到105 CFU/g以上可以检测到SEC, 累计到107 CFU/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。

英文摘要:

      Objective To investigate the correlation between the growth of Staphylococcus aureus (SA) and expression of staphylococcal enterotoxins (SE) including SEA, SEB and SEC on strawberry. Methods The enterotoxin strains were confirmed, 104 CFU/g and 102 CFU/g of bacteria were prepared and artificial pollution to the strawberry by immersion method. According to GB 4789, SA and staphylococcal enterotoxins (A-C) of strawberry were counted and detected in the storage process of 8 ℃ and 25 ℃. Results Under the suitable conditions, regardless of initial contamination level of SA in strawberry could normal growth and produce enterotoxin, especially the production of SEA was higher than that of SEB and SEC quickly. Among them, SEA could be detected from the sample when SA accumulated to more than 104 CFU/g at 25 ℃ storage conditions, accumulated to more than 105 CFU/g would be able to detect SEC, accumulated to more than 107 CFU/g would be able to detect SEB. SE were not detected at 8 ℃ within 48 h. Conclusion The correlation between the growth of SA and expression of SE on strawberry were studied, which would be valuable to the microbiological risk assessment and standards setting of strawberry.