Utilization of octopine and nopaline by Agrobacterium

Abstract

Tests for utilization of D octopine and nopaline in defined media containing a carbon and nitrogen source were made on 60 strains of Agrobacterium representing 4 species and on a representative of each of 5 species of Rhizobium. Among 46 virulent strains of Agrobacterium, only 2 strains were found which utilized neither compound, while 3 strains were found which could utilize both. Of the remaining virulent strains, 27 utilized octopine and 14 utilized nopaline. Each of 6 strains of A. rhizogenes tested utilized only octopine but at a slower rate relative to growth than most A. tumefaciens. All 8 of the A. radiobacter strains failed to utilize either compound, as did 4 of 6 nonvirulent strains of A. tumefaciens. The rhizobia did not utilize octopine, or, with the possible exception of R. japonicum, nopaline. Virulence in the genus Agrobacterium is concluded to be highly correlated with the ability to utilize 1 or both of these compounds.