Abstract Bacillus cereus may cause two different types of foodborne illness: diarrheal and emetic syndromes. Dried infant formulae are at risk of contamination by the B. cereus, which is reflected by the requirement for the microbiological examination of foods listed in Regulation (EC) 2073/2005, as amended. This study evaluates the growth and toxin production potential of B. cereus in reconstituted dried infant milk formula. Powdered milk was inoculated with approximately 1 log and 3 log cfu g−1 of spore suspension of toxigenic B. cereus strains and then stored as reconstituted milk for 48 h at 8 °C, 15 °C, and 24 °C. The growth of B. cereus, tested by the plate method, and production of the emetic toxin and enterotoxins, tested by the gold-labelled immunosorbent assay, were regularly detected during 48 h of storage. The Baranyi-Roberts model was used to study the growth potential of B. cereus strains. In reconstituted infant milk, B. cereus did not grow at 8 °C during 48 h of storage. B. cereus multiplied and formed toxins only at 15 °C and 24 °C. The growth curve of the bacteria stored at 15 °C included the lag and exponential phases, and the growth was not completed during the period. The growth of B. cereus at 24 °C was completed, peaking within 27 and 20 h, with the low and high inoculum sizes, respectively. Detectable amounts of toxins were formed during the bacterial growth of around 5 log cfu ml−1 (non-hemolytic enterotoxin) and 7 log cfu ml−1 (hemolysin BL and emetic toxin). Model experiments evaluated consumer risk from B. cereus toxins resulting from extended storage of reconstituted infant milk formula at improper temperatures.

中文翻译：

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重构初始婴儿配方奶粉中蜡状芽孢杆菌菌株的生长和毒素产生

摘要 蜡样芽孢杆菌可能导致两种不同类型的食源性疾病：腹泻和呕吐综合征。干婴儿配方奶粉有被蜡状芽孢杆菌污染的风险，这反映在法规 (EC) 2073/2005 修订版中列出的食品微生物检查要求中。本研究评估了重组婴儿奶粉中蜡状芽孢杆菌的生长和毒素产生潜力。奶粉接种了大约 1 log 和 3 log cfu g-1 的产毒蜡状芽孢杆菌菌株的孢子悬浮液，然后作为复原乳在 8 °C、15 °C 和 24 °C 下储存 48 小时。在 48 小时的储存期间，定期检测蜡样芽孢杆菌的生长，通过平板法测试，以及通过金标记免疫吸附试验测试的催吐毒素和肠毒素的产生。Baranyi-Roberts 模型用于研究蜡状芽孢杆菌菌株的生长潜力。在复原婴儿奶中，蜡样芽孢杆菌在 8 °C 的储存 48 小时内没有生长。B. cereus 仅在 15 °C 和 24 °C 下繁殖并形成毒素。15℃保存的细菌生长曲线包括滞后期和指数期，在此期间生长没有完成。B. cereus 在 24 °C 下生长完成，在 27 和 20 小时内达到峰值，分别具有低和高接种量。在大约 5 log cfu ml-1（非溶血性肠毒素）和 7 log cfu ml-1（溶血素 BL 和催吐毒素）的细菌生长过程中形成了可检测量的毒素。模型实验评估了消费者因在不当温度下长期储存复原婴儿配方奶粉而产生蜡样芽孢杆菌毒素的风险。