The genus bdellovibrio and like organisms

Abstract

Bdellovibrio and like organisms (BALOs) are gram-negative, obligate predators of other gram-negative bacteria. These small bacteria interact with their prey as highly motile attack phase cells, attaching to the outer membrane and consuming the prey extracellularly (epibiotic predation) or penetrating their periplasm (periplasmic predation). The former divides in a binary fashion, while the latter grows as a polynucleotide filament to finally split as progeny attack cells. High-resolution microscopy, molecular genetics, genomics, and functional genomics have been applied to study the cell cycle of BALOs, revealing functions required for predation and for cellular organization. Until recently, Bdellovibrio bacteriovorus was the only recognized species of BALOs. Culture-dependent and culture-independent approaches have shown that these predators form diverse monophyletic groups, including the three families Bdellovibrionaceae, Bacteriovoraceae, and Peridibacteraceae in the δ-proteobacteria, and the genus Micavibrio in the α-proteobacteria. Based on this detailed taxonomical knowledge, it has become possible to track predator and prey interactions in natural systems, providing first evaluations of the impact of bacterial predation on community structure.