ISOLATION AND CHARACTERIZATION OF BACTERIOPHAGES FOR CAULOBACTER-CRESCENTUS

Thirty-eight viruses capable of infecting C. crescentus were isolated. Of these isolates, 28 were DNA phages with a prolate cylindrical head and a long flexible tail. Each of them infected only 1 Caulobacter cell type, the swarmer cell, and many proved to be capable of establishing a lysogenic relationship with their host. Despite structural similarity and host cell specificity, the majority of these DNA phages appeared to be genetically distinct as shown by EcoRI restriction patterns of their DNA and by host range on phage resistant and lysogenic strains. Two isolates were small RNA phages, structurally similar to the Escherichia coli RNA phages, which specifically adsorbed to pili on the Caulobacter swarmer cell. The remaining 8 isolates were DNA phages with polyhedral heads ranging from 60-160 nm in diameter. Six had contractile tails ranging from 50-160 nm in length, while 2 had long flexible non-contractile tails. Each of these isolates was capable of attaching to all Caulobacter cell types and 2 were capable of mediating generalized transduction between strains of Caulobacter.