Using an insect model to assess correlation between temperature and virulence in Bacillus weihenstephanensis and Bacillus cereus

• Published in: FEMS microbiology letters Vol. 317; no. 2; pp. 196 - 202
• Main Authors: Stenfors Arnesen, Lotte, Granum, Per Einar, Buisson, Christophe, Bohlin, Jon, Nielsen-LeRoux, Christina
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-04-2011; Wiley-Blackwell; Oxford University Press
• Subjects: Agricultural sciences; Animals; Bacillus - pathogenicity; Bacillus cereus; Bacillus cereus - pathogenicity; Bacillus weihenstephanensis; Bacterial Proteins - genetics; Bacterial Proteins - physiology; Bacteriology; Biocompatibility; Biological and medical sciences; Cell culture; Cercopithecus aethiops; cereulide; Cytotoxicity; Foodborne diseases; Fundamental and applied biological sciences. Psychology; Galleria mellonella; Hbl; insect in vivo model; Insecta - microbiology; Insects; Life Sciences; Microbiology; Miscellaneous; Nhe; Species; Strains (organisms); Temperature; Temperature dependence; Temperature effects; Toxicity; toxins; Vero Cells; Virulence; Virulence - genetics; Virulence - physiology; insect; model; Nhe; Hbl; cereulide; toxins; Temperature; Insecta; Virulence; Bacillaceae; insect in vivo model; Toxin; Bacillus cereus; Bacillales; Arthropoda; Bacteria; Models; Invertebrata; STRAINS; CELLS; TOXIN; IDENTIFICATION; DIARRHEAL ENTEROTOXIN; RPLA; THURINGIENSIS; INFECTION; NONHEMOLYTIC ENTEROTOXIN COMPLEX; FOOD
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1111/j.1574-6968.2011.02229.x

Abstract
The closely related bacterial species Bacillus cereus and Bacillus weihenstephanensis are adapted to the mesophilic and the psychrotrophic temperature range, respectively. While B. cereus strains are associated with foodborne diseases, B. weihenstephanensis strains are so far not, although similar virulence genes are found in both species. Our investigations show that both species were virulent in the insect model, Galleria mellonella, following infection via oral and haemocoel routes. However, virulence of B. weihenstephanensis was much higher at 15°C than at 37°C. Furthermore, a temperature-dependent difference between the species was seen in a cell culture cytotoxicity assay. In summary, our results demonstrate for the first time virulence of B. weihenstephanensis strains in an in vivo model. In addition, we found that G. mellonella is a useful model for studies of the psychrotolerant species of the B. cereus group, suggesting that insects might be an ecological growth niche for several members of this bacterial group.