Investigation of toxin production by Bacillus cereus, characterization and detection of the strains responsible for food poisoning

General introduction

Bacillus cereus is a sporeforming food pathogen which can cause a toxico-infection responsible for either vomiting or diarrhea. This project focuses on the diarrhea-causing type, a genetically heterogenous type. ILVO coordinates a project consortium including Ghent University, UCL, WIV. This consortium explores the genetic variation within this Bacillus species. The circumstances of enterotoxinproduction in the small intestine are described. The aim is to identify scientific elements that facilitate thorough hazard characterisation and efficient control measures throughout the food chain.

Research approach

A quantitative LC-MS method is being developed for the B. cereus enterotoxins CytK and Nhe using pure cultures and small intestine samples. The behaviour of B. cereus is then thoroughly investigated in a simulation model of the human gastrointestinal tract, the SHIME reactor. The growth kinetics and enterotoxin production of psychrotolerant and mesophilic strains in vegetative and spore form are investigated under the conditions of the small intestine. The genetic and genomic diversity of a carefully selected collection of diarrhea causing B. cereus strains are investigated with an MLST analysis of the toxin genes cytK and nhe and their genetic surroundings. Finally, we use a retrospective analysis, predictive modelling and synthesis of all project data to identify hazardous contamination levels and relevant food items for public health purposes.

Relevance/Valorisation

The increasing popularity of ready-to-eat or ready-to-cook food makes Bacillus cereus an emerging pathogen, but the pathotypes associated with gastroenteritis are not yet well described. The project yields more information and tools to characterize the potentially most hazardous strains and conditions (both in food and in the gut). This study leads to a detailed characterization of the risk of B. cereus diarrheal food intoxication in terms of strain/type, food type and contamination level.

External partner(s)
UCL - Université Catholique de Louvain-la-Neuve - Fac. D'ingénieri biologique, agronomique et Environnementale - AGRO
Ugent - Fac. Bio-ingenieurswetenschappen
UGent - Fac. Wetenschappen
WIV - Wetenschappelijk Instituut voor Volksgezondheid