A novel assay to monitor predator-prey interactions for Bdellovibrio bacteriovorus 109 J reveals a role for methyl-accepting chemotaxis proteins in predation

Bdellovibrio bacteriovorus are Gram-negative bacteria that prey upon other Gram-negative bacteria, including some pathogens, in a wide variety of habitats including soil, sewage, marine and estuarine environments. In order to facilitate studies on predation by this organism, we have developed a method that assays killing of luminescent Escherichia coli by B. bacteriovorus . Moreover, we have used this assay to compare predation of cells by derivatives of B. bacteriovorus containing targeted mutations in genes we have identified. Two genes are described; one, mcp2 , encoding a methyl-accepting chemotaxis protein (MCP) and the other, an mviN homologue. Bdellovibrio bacteriovorus mcp2::aphII were less efficient predators on luminescent E. coli than B. bacteriovorus containing a randomly inserted aphII gene via TnphoA transposition. These and other chemotaxis experiments implicated at least a minor role for chemotaxis in predation by B. bacteriovorus. They also open the way for further studies on Bdellovibrio ecology, genomics and predator-prey interactions. The results further confirm that Bdellovibrio uses a chemotaxis system in order to sense, and respond to, changes in its environment, including prey.