This study addresses the biodiversity of Bacillus cereus group population present along the value chain of milk for consumption. The B. cereus population did not grow and remained mainly unaltered during storage of milk at 4 °C while storage at a suboptimal temperature at 8 °C (representative of a broken cold chain) caused a major shift in its composition. Mesophilic strains dominated the B. cereus population in raw milk and after storage at 4 °C, while psycrotrophic strains dominated after storage at 8 °C. All psycrotrophic and mesophilic isolates (n = 368) demonstrated high spoilage potentials of the milk components. Fifteen out of 20 mesophilic isolates but only two out of 40 psychrotrophic isolates, exhibited vero cell toxicity. No genes encoding the emetic toxin cereulide were detected in the genomes of 100 milk isolates while 14 of them harbored the enterotoxin genes cytK1/cytK2. Both psycrotrophic and mesophilic isolates carried the enterotoxin genes nheA and hblA. Together, the results provide insight into the composition and properties, of the B. cereus population present in milk along the value chain and during storage at optimal refrigerated temperature and at suboptimal temperature. This knowledge is useful in the dairy industry's work to assure high quality products and for risk assessment.

这项研究解决了在食用牛奶价值链上存在的蜡状芽孢杆菌种群的生物多样性。的蜡状芽孢杆菌的人口不生长，并在4℃下的牛奶贮存期间保持不变为主而存储在次优的温度在8℃下（代表一个破碎冷链的）引起在其组成中的重大转变。中温菌株在蜡状芽孢杆菌中占主导地位在4°C下储存后，原奶中的细菌数量增加，而在8°C下储存后，营养细菌菌株占主导地位。所有的嗜营养菌和嗜温菌分离物（n = 368）均显示出牛奶成分极易变质。在20种嗜温菌中，有15种表现出维罗细胞毒性，而在40种精神营养菌中，只有2种表现出维罗细胞毒性。在100个牛奶分离物的基因组中没有发现编码催吐毒素蜡状内酯的基因，其中14个含有肠毒素基因cytK1 / cytK2。嗜营养菌和中温菌都携带肠毒素基因nheA和hblA。在一起，结果提供了对蜡状芽孢杆菌的组成和性质的了解。价值链中以及在最佳冷藏温度和次优温度下储存期间，牛奶中存在的细菌数量。这些知识对于乳制品行业的工作很有用，以确保高质量的产品和风险评估。