Effects of porcine bile on survival of Bacillus cereus vegetative cells and Haemolysin BL enterotoxin production in reconstituted human small intestine media
Article first published online: 19 JUN 2007
© 2007 The Authors. Journal compilation © 2007 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 103, Issue 5, pages 1568–1575, November 2007
How to Cite
Clavel, T., Carlin, F., Dargaignaratz, C., Lairon, D., Nguyen-The, C. and Schmitt, P. (2007), Effects of porcine bile on survival of Bacillus cereus vegetative cells and Haemolysin BL enterotoxin production in reconstituted human small intestine media. Journal of Applied Microbiology, 103: 1568–1575. doi: 10.1111/j.1365-2672.2007.03410.x
- Issue published online: 19 JUN 2007
- Article first published online: 19 JUN 2007
- 2006/0539: received 18 April 2006, revised 9 February 2007 and accepted 27 February 2007
- Bacillus cereus;
- porcine bile;
- small intestine;
Aims: To determine the effects of porcine bile (PB) on Bacillus cereus vegetative cells and Haemolysin BL (HBL) enterotoxin production in reconstituted small intestine media (IM).
Methods and Results: The effects of PB on the growth of B. cereus vegetative cells in reconstituted IM at PB concentrations ranging between 0 and 3·0 g l−1 were examined. Four gastric media (GM) named GM-J broth (JB), GM-chicken, GM-milk and GM-pea were prepared by mixing equal volumes of a gastric electrolyte solution containing pepsin with JB, chicken, semi-skimmed milk and pea soup, respectively. Bacillus cereus was inoculated at approx. 2 × 104 CFU ml−1 into each GM at pH 5·0 for 30 min at 37°C, then mixed to the same volume of double-strength JB (IM) and PB to give concentrations of between 0 and 3·0 g of PB per litre at pH 6·5 and incubated at 37°C. The diarrhoeal B. cereus strain F4430/73 grew in IM-JB, IM-chicken and IM-milk at PB concentrations of up to 0·6, 1·5 and 1·2 g l−1, respectively. Growth was observed in IM-pea at all concentrations tested. The highest PB concentrations allowing a 3 log B. cereus increase in IM-JB, IM-chicken, IM-milk and IM-pea after a 7–10 h incubation period were 0·3, 0·9, 0·9 and 3·0 g l−1, respectively. The effect of PB on B. cereus cells was strongest in IM-JB, followed by IM-chicken, IM-milk and IM-pea. Haemolysin BL enterotoxin was detectable in IM-chicken, IM-whole milk, IM-semi-skimmed milk and IM-pea up to PB concentrations of only 0·6, 0·6, 0·3 and 0·9 g l−1, respectively. The diarrhoeal B. cereus strain F4433/73 behaved similarly to B. cereus strain F4430/73, whereas the food strain TZ415 was markedly more susceptible to bile.
Conclusions: The tolerance of B. cereus cells to PB strongly depends on the type of food contained in the IM. Bile tolerance is also subject to strain variation.
Significance and Impact of the Study: The probability that B. cereus cells will grow in the small intestine, produce toxins and cause diarrhoea is likely to depend on the food they are ingested with, on the bile tolerance of the B. cereus strain, and on bile concentration.