Studies on Certain Physiological Characters ofPhytomonas tumefaciens, Phytomonas rhizogenesandBacillus radiobacter

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Abstract
Studies were made, with single-cell cultures of the 3 spp., on physiological differences and on variations within the same group under different conditions. The pathogenicity of all the cultures was studied in connection with their physiological behavior. Differences in physiological behavior were noted in respect to: (1) reduction of Na selenite; (2) either absorption or bacteriostatic effects with dahlia, thionin, Bismarck brown, and aniline blue; (3) types of growth in several media in which oxidation-reduction potentials were varied. The oxidation-reduction potentials of a ferric-ammonium-citrate medium and of a mannitol anilin-blue medium were lowered in a similar manner by these organisms. For isolations of cultures from crown-gall, a yeast-water mannitol medium with aniline blue proved useful. Variations in physiological and pathogenic reactions of the 55 cultures were not obtained by continuous cultivation in artificial media. However, a non-pathogenic crown-gall culture was secured by colony isolations from a single-cell parent. Variations in the physiological behavior of the crown-gall organism were obtained by plant passage; they involved (1) S and R colonies, (2) reaction in KNO3 glycerol phenol-red broth, (3) dye absorption in yeast-water mannitol aniline-blue medium, and (4) formation of a serum zone in milk. Plant passage had no apparent effect on its virulence.