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Poster De Conférence Année : 2017

Genetic diversity of Bacillus cereus group strains isolated from food in Tunisia

Résumé

It is widely acknowledged that bacteria belonging to the Bacillus cereus group are found in a wide range of environments including foods. In addition to their ubiquitous and spore-forming characteristics, these bacteria are able to form biofilms and can resist industrial pasteurization. Several strains of this group are thus recognized as causing food spoilage and/or sanitary problems. In this study, a total of 687 food samples were collected in Tunisia (cereals, spices, cooked food, canned products, seafood products, dairy products, fresh-cut vegetables, raw and cooked poultry meats) and searched for the presence of the B. cereus group after enrichment and selective plating on mannitol-egg-yolk polymyxin agar. One characteristic B. cereus colony from each selective agar plate was re-isolated and frozen after individual cultivation. Overall, 193 food samples (28%, n=687) were found positive, giving rise to a collection of 193 isolates. This collection was subjected to a PCR test targeting a specific sequence of the sspE gene in order to verify whether they belonged to the B. cereus group. One hundred and seventy four isolates (90.1 %) were found to be positive. Food samples were contaminated as follows: cereals (67.6%), pastry products (46.2%), cooked food (40.8%), cooked poultry meat (32.7%), seafood products (32.3%), spices (28.8%), canned products (16.7%), raw poultry meat (9.4%), freshcut vegetables (5.0%), and dairy products (4.8%). The 174 B. cereus group isolates were characterized by partial sequencing of the panC gene, using a Sym’Previous software tool to assign them to different phylogenetic groups. Strains were distributed as follows: 61.3% in the group III, 29.5 % in the group IV, 7.5% in the group II and 1.7% in the group V. The genetic diversity was further assessed by ERIC-PCR and PFGE. A wide range of typing profiles was highlighted, even within the same food sample and/or within the same phylogenetic group. The results also showed that PFGE had a higher discriminatory power than ERIC-PCR.
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Dates et versions

hal-02735522 , version 1 (02-06-2020)

Identifiants

  • HAL Id : hal-02735522 , version 1
  • PRODINRA : 493793

Citer

Maroua Gdoura, Mariam Siala, Mariem Zayani, Noel Grosset, Feriele Messadi-Akrout, et al.. Genetic diversity of Bacillus cereus group strains isolated from food in Tunisia. Microbial spoilers in food, Jun 2017, Quimper, France. , 2017. ⟨hal-02735522⟩
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