Bdellovibrio bacteriovorus , a Gram negative predatory bacterium, is known to have an extremely high metabolic rate. While searching for prey cells, Bdellovibrio cells quickly begin to die unless provided with glutamate or TCA cycle intermediates, suggesting a powerful role for this portion of prokaryotic central metabolism. As a starting point for analysis, the citrate synthase and glutamine synthetase genes from Bdellovibrio have been cloned, and molecular genetic analysis of these genes has begun. The citrate synthase and glutamine synthetase genes were cloned by functional complementation of E. coli auxotrophic mutants with a Bdellovibrio genomic cosmid library, and confirmed by retransformation. Currently, work is under way to localize the genes within insert DNA by subcloning, transposon mutagenesis, and DNA sequencing. We hope that understanding these genes and enzymes, which are crucial to the TCA cycle, will provide insight into the life cycle of this unusual and highly active predator bacterium.