Incidence and characterisation of aerobic spore-forming bacteria originating from dairy milk in Tunisia

Authors

  • Chedia Aouadhi,

    Corresponding author
    1. Laboratory of Epidemiology and Microbiology, Bacteriology and Biotechnology development Groups, Pasteur Institute of Tunisia (IPT), University Manar, Tunis, Tunisia
    2. Laboratory of Animal Resources and Food Technology, National Institute of Agronomy Tunis (INAT), University Carthage, Tunis, Tunisia
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  • Abderrazak Maaroufi,

    1. Laboratory of Epidemiology and Microbiology, Bacteriology and Biotechnology development Groups, Pasteur Institute of Tunisia (IPT), University Manar, Tunis, Tunisia
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  • Slah Mejri

    1. Laboratory of Animal Resources and Food Technology, National Institute of Agronomy Tunis (INAT), University Carthage, Tunis, Tunisia
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Abstract

The purpose of this study was to evaluate the incidence and characterisation of aerobic spore-forming bacteria originating from dairy milk in Tunisia. The distribution of Bacillus species in raw milk, pasteurised milk and UHT milk were 47.5%, 27.5% and 25%, respectively. Seven Bacillus species, including Bacillus pumilus (10%), Bacillus subtilis (12.5%), Brevibacillus brevis (10%), Bacillus cereus (22.5%), Bacillus sphaericus (7.5%), Bacillus licheniformis (12.5%) and Bacillus sporothermodurans (25%) were identified in different milk samples. Bacillus 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 Bacillus isolates from Tunisian milk and the persistence of spoilage risk in UHT milk.

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