Spatially-resolved Sequence Analysis of hit gene in B. bacteriovorus Biofilms
Mentor:Eileen M. Spain, Professor, Chemistry, Occidental College
Bdellovibrio bacteriovorus is an obligate gram-negative bacterium that preys upon other gram-negative bacteria in the process of its life cycle. Studies on this organism highlight a small gene (306 bp) called the hit locus that maintains cell invasion and predation behaviors. This investigation emphasizes the lifestyle of Bdellovibrio bacteriovorus through the functionality of the hit locus as it preys upon Escherichia coli when trapped on nutrient-rich surface. When a small volume of host-dependent (HD) wildtype bdellovibrios grown in a nutrient poor media is deposited on a nutrient-rich surface with remaining E. coli prey cells, a structured biofilm develops over a period of one to two week. This biofilm displays two concentric regions that differ in color: an inner yellow-colored circle and a cream-colored outer ring. Through PCR and gel electrophoresis analysis of these regions, several findings are observed that definitively show an inner sequestration of the wild type predators within the biofilm, seen through analysis of the hit locus. It is speculated that this phenotypic organization is based on interspecies signaling in order to benefit a spectrum of variants. The mechanism for the spatial separation of the phentoypes of bdellovibrios is the subject of a new line of study in this laboratory.