A ferric dicitrate uptake system is required for the full virulence of Bacillus cereus

Bacillus cereus is an opportunistic human pathogen of increasing prevalence. Analysis of the Bacillus cereus genome sequence identified a potential ferric dicitrate uptake system. The three-gene operon was confirmed to be negatively regulated by the ferric uptake repressor (Fur). The Fee operon was genetically silenced using the integration suicide vector pMUTIN4. The mutant strain displayed no growth defect under iron-limited conditions but was unable to grow on ferric citrate as a sole iron source. The virulence of the mutant strain was attenuated in a lepidopteran infection model, highlighting the importance of iron uptake systems to the virulence of B. cereus and the potential of these systems to act as targets for novel antimicrobial agents.