Incidence and characterisation of aerobic spore‐forming bacteria originating from dairy milk in T unisia

The purpose of this study was to evaluate the incidence and characterisation of aerobic spore‐forming bacteria originating from dairy milk in T unisia. The distribution of B acillus species in raw milk, pasteurised milk and UHT milk were 47.5%, 27.5% and 25%, respectively. Seven B acillus species, including B acillus pumilus (10%), B acillus subtilis (12.5%), B revibacillus brevis (10%), B acillus cereus (22.5%), B acillus sphaericus (7.5%), B acillus licheniformis (12.5%) and B acillus sporothermodurans (25%) were identified in different milk samples. B acillus cereus was predominant in raw and pasteurised milk. Although B . sporothermodurans was the predominant sporogenous micro‐organism in UHT milk, B . cereus , B . sphaericus and B . licheniformis were also present. This study showed that there is a high degree of diversity, both phenotypic and genotypic, among B acillus isolates from T unisian milk and the persistence of spoilage risk in UHT milk.