PARASITISM OF AZOTOBACTER AND RHIZOBIUM SPECIES BY BDELLOVIBRIO BACTERIOVORUS

Attempts to isolate, from soil, strains of Bdellovibrio bacteriovorus parasitic on various Azotobacter and Rhizobium species were not successful. However, a strain of Bdellovibrio bacteriovorus isolated from soil as a parasite of Escherichia coli was shown to produce plaques on Azotobacter chroococcum as well but not on Azotobacter vinelandii or various Rhizobium species. The nutritive conditions required for this Bdellovibrio strain to yield discrete countable plaques on Azotobacter chroococcum plates were examined, and it was proposed that Azotobacter slime be used as a preservative agent for the maintenance of Bdellovibrio bacteriovorus strains in frozen culture. © 1968 Swets & Zeitlinger.