LAUSR

Burkholderia pseudomallei (Bp) and Burkholderia mallei (Bm) cause the often-lethal infectious diseases melioidosis and glanders, respectively. Curiously, closely related species within the Bp complex share a nearly identical arsenal of virulence traits, yet are harmless to humans. Clues to the origin of virulence in this group can be found in their genetics and ecology. As a resident of the rhizosphere, Bp faces competition for nutrients and predation by other organisms. Adaptation over millennia has enabled Bp to accumulate mechanisms that overlap in their ability to promote fitness in the environment and virulence in mammals. Here, we review the ecology of Bp and its range of virulence attributes, and offer hypotheses on the evolution of virulence in the Bp complex which are relevant to other environmental pathogens.