Comparative phenotypic, genotypic and genomic analyses of Bacillus thuringiensis associated with foodborne outbreaks in France

PLoS One. 2021 Feb 19;16(2):e0246885. doi: 10.1371/journal.pone.0246885. eCollection 2021.

Abstract

Bacillus thuringiensis (Bt) belongs to the Bacillus cereus (Bc) group, well known as an etiological agent of foodborne outbreaks (FBOs). Bt distinguishes itself from other Bc by its ability to synthesize insecticidal crystals. However, the search for these crystals is not routinely performed in food safety or clinical investigation, and the actual involvement of Bt in the occurrence of FBOs is not known. In the present study, we reveal that Bt was detected in the context of 49 FBOs declared in France between 2007 and 2017. In 19 of these FBOs, Bt was the only microorganism detected, making it the most likely causal agent. Searching for its putative origin of contamination, we noticed that more than 50% of Bt isolates were collected from dishes containing raw vegetables, in particular tomatoes (48%). Moreover, the genomic characterization of isolates showed that most FBO-associated Bt isolates exhibited a quantified genomic proximity to Bt strains, used as biopesticides, especially those from subspecies aizawai and kurstaki. Taken together, these results strengthen the hypothesis of an agricultural origin for the Bt contamination and call for further investigations on Bt pesticides.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus thuringiensis / genetics*
  • Food Microbiology*
  • France
  • Genome, Bacterial / genetics
  • Genomics*
  • Genotype*
  • Phenotype*

Grants and funding

This project was funded and supported by ANSES (PPV project “Bt-TIAC”, 2018) via the tax on sales of plant protection products. The proceeds of this tax are assigned to ANSES to finance the establishment of the system to monitor the adverse effects of plant protection products, called “phytopharmacovigilance” (PPV), established by the French Act on the future of agriculture of 13 October 2014.