Predator Versus Pathogen: How Does Predatory Bdellovibrio bacteriovorus Interface with the Challenges of Killing Gram-Negative Pathogens in a Host Setting?

Bdellovibrio bacteriovorus is a small deltaproteobacterial predator that has evolved to invade, reseal, kill, and digest other gram-negative bacteria in soils and water environments. It has a broad host range and kills many antibiotic-resistant, clinical pathogens in vitro, a potentially useful capability if it could be translated to a clinical setting. We review relevant mechanisms of B. bacteriovorus predation and the physiological properties that would influence its survival in a mammalian host. Bacterial pathogens increasingly display conventional antibiotic resistance by expressing and varying surface and soluble biomolecules. Predators coevolved alongside prey bacteria and so encode diverse predatory enzymes that are hard for pathogens to resist by simple mutation. Predators do not replicate outside pathogens and thus express few transport proteins and thus few surface epitopes for host immune recognition. We explain these features, relating them to the potential of predatory bacteria as cellular medicines.