CHARACTERIZATION OF RHIZOBIA ISOLATED FROM SAINFOIN (ONOBRYCHIS-SATIVA)

Six rhizobial strains isolated from the root nodules of sainfoin (Onob rychis sativa) in Bulgaria and six strains of sainfoin rhizobia from o ther geographical regions were characterized physiologically, biochemi cally and symbiotically. On the basis of the results obtained on the u tilization of carbon sources by the strains investigated, their intrin sic antibiotic resistance, their tolerance to NaCl, temperature and th e pH of the medium, it was concluded that the rhizobia isolated from s ainfoin nodules formed a homogeneous group, regardless of their geogra phical origin although they differed in their symbiotic properties. In respect of the plasmid contents four groups of strains were revealed: a group of six strains with two plasmids (similar to 450 kb and simil ar to 100 kb); a second group of four strains with one 'common' plasmi d (similar to 450 kb); one strain with only one plasmid, different in size from the plasmids of the other strains; and one strain in which n o plasmid could be detected. Five of the Bulgarian strains were more e ffective with O. sativa than the strains from other regions.