title: Plasmid exchanges among members of the Bacillus cereus group in foodstuffs.
abstract: The Bacillus cereus sensu lato group is genetically very close and possesses a remarkable plasmid gene pool that encodes a variety of functions such as virulence and self-transfer capabilities. The potential for horizontal transfer among the various subspecies of this group, which includes the human opportunistic pathogens B. cereus sensu stricto and B. anthracis as well as the biopesticide B. thuringiensis, has led to growing concerns regarding food safety and public health. In this study, the conjugative behaviour of B. thuringiensis strains was compared in LB medium, milk and rice pudding using the pXO16 and pAW63 conjugative systems, as well as the mobilisable plasmid pC194, in bi- and triparental matings. Conjugation and mobilisation of these plasmids were shown to occur at significant levels in both food products, attaining the highest transfer frequencies in milk, with an approximately ten-fold increase in conjugative transfer in this growth medium as compared to liquid LB. Furthermore, the ability of an emetic strain of B. cereus to function as either plasmid donor or recipient partner in heterologous biparental matings with B. thuringiensis was demonstrated in these food matrices.
authors.affiliation: Laboratory of Food and Environmental Microbiology, Université catholique de Louvain, Croix du Sud, 2/12, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Géraldine A
authors.initials: GA
authors.lastname: Van der Auwera
authors.forename: Sophie
authors.initials: S
authors.lastname: Timmery
authors.forename: Florence
authors.initials: F
authors.lastname: Hoton
authors.forename: Jacques
authors.initials: J
authors.lastname: Mahillon
mesh_terms: D000818:Animals; D001408:Bacillus anthracis; D001409:Bacillus cereus / Q000235:genetics / Q000502:physiology*; D001413:Bacillus thuringiensis / Q000235:genetics / Q000502:physiology*; D003227:Conjugation, Genetic; D003257:Consumer Product Safety; D003433:Crosses, Genetic; D005516:Food Microbiology; D008892:Milk / Q000382:microbiology*; D010957:Plasmids; D011634:Public Health; D013045:Species Specificity