Spatially Organized Films from Bdellovibrio bacteriovorus Prey Lysates

Bdellovibrio bacteriovorus is a Gram-negative predator of other Gram-negative bacteria. Interestingly,Bdellovibrio bacteriovorus 109J cells grown in coculture withEscherichia coli ML-35 prey develop into a spatially organized two-dimensional film when located on a nutrient-rich surface. From deposition of 10 μl of a routine cleared coculture ofB. bacteriovorus andE. coli cells, the cells multiply into a macroscopic community and segregate into an inner, yellow circular region and an outer, off-white region. Fluorescencein situ hybridization and atomic force microscopy measurements confirm that the mature film is spatially organized into two morphologically distinctBdellovibrio populations, with primarily small, vibroid cells in the center and a complex mixture of pleomorphic cells in the outer radii. The interior region cell population exhibits the hunting phenotype while the outer region cell subpopulation does not. Crowding and high nutrient availability with limited prey appear to favor diversification of theB. bacteriovorus population into two distinct, thriving subpopulations and may be beneficial to the persistence ofB. bacteriovorus in biofilms.