How <i>Bdellovibrio bacteriovorus</i> became a model for invasive bacterial predation

ABSTRACT Bdellovibrio bacteriovorus is a gram-negative Proteobacterium that has evolved to use a novel, predatory, intrabacterial lifestyle. Once encountered under a microscope, in a lecture, or a textbook, it is seldom forgotten. B. bacteriovorus speedily collides with, enters, modifies, and kills other gram-negative bacteria. Residing inside the periplasm of the dead prey for several hours, it uses prey molecules for growth and replication, only bursting out from that temporary home when its progeny are fully formed predators themselves. Rapid motility whilst hunting contrasts with sessility during prey consumption—these key behaviors, studied by early researchers, have been followed by molecular studies in recent times. Genomic analysis has enabled the linkage and discovery of proteins involved in key regulatory circuits, allied to enzymology describing prey cell manipulation and deconstruction. Indeed, the prey bacterium of a B. bacteriovorus is the natural “petri dish” of suitable components for predator growth. A fascinating B. bacteriovorus conundrum continues to be: “how does a predator consume materials very similar to those from which it is built, without self-damage?”. More has been discovered and is yet to be learned about these bacterial damaging enzymes: how predators use them in nature and whether they can be applied to assist human conflicts with pathogens. However, the elegance and molecular complexity, with which B. bacteriovorus accomplishes its intrabacterial lifestyle, will continue to challenge researchers and present new biology in the 21st century. New discoveries, tools, and approaches position B. bacteriovorus research for many more breakthroughs.