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Intraspecific Diversity and Pathogenicity of Bacillus thuringiensis Isolates from an Emetic Illness

Jintana Pheepakpraw1,2, Thida Kaewkod1, Maytiya Konkit3

  • 1Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.

Toxins
|February 24, 2023
PubMed

Insights

This study identified Bacillus thuringiensis as the cause of emetic food-borne illness. The bacteria possessed genes for cereulide toxin and induced cell death via necrosis, highlighting a novel pathogenic mechanism.

Area of Science:

  • Microbiology
  • Food Safety
  • Toxicology

Background:

  • Emetic food-borne intoxication is often linked to Bacillus cereus group species.
  • Understanding the specific bacterial species and their pathogenic mechanisms is crucial for public health.

Purpose of the Study:

  • To characterize bacterial isolates from an emetic food-borne intoxication incident.
  • To investigate the molecular, genetic, and cytotoxic properties of these isolates related to emetic illness.

Main Methods:

  • Polyphasic identification and multilocus sequence typing (MLST) were used for bacterial characterization.
  • Analysis of the cereulide synthetase (ces) gene cluster and cytotoxicity assays on Caco-2 cells were performed.
  • Flow cytometry (Annexin V/PI assay) was employed to determine cell death mechanisms.

Main Results:

  • All seven isolates were identified as Bacillus thuringiensis, exhibiting intraspecific diversity via MLST.
  • Isolates harbored gene fragments within the ces gene cluster, indicating potential for cereulide production.
  • Toxic supernatants from three isolates induced vacuolation and cell death in Caco-2 cells, primarily through necrosis.

Conclusions:

  • Bacillus thuringiensis can be an agent of emetic food-borne illness.
  • The identified isolates possess genetic factors and cytotoxic potential linked to emetic toxin production.
  • Necrosis is a significant mechanism of Caco-2 cell destruction by these toxic B. thuringiensis isolates.
Keywords:
Bacillus cereus groupBacillus thuringiensisCaco-2 cellscereulide synthetase genecytotoxicityemetic toxinfoodborne intoxicationfoodborne outbreak

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