Genome analysis of Bradyrhizobium japonicum serocluster 123 field isolates by using field inversion gel electrophoresis

The genomes of 11 Bradyrhizobium japonicum serocluster 123 field isolates were analyzed by using field inversion gel electrophoresis. Genomic fingerprints produced by digestion of intact genomic DNA in agarose plugs with the rare-cutting restriction enzymes AseI, DraI, SpeI, and XbaI showed that the isolates were genetically diverse. Few (30 to 50%) isolates exhibited the same fingerprint as the USDA serogroup strain with which they are antigenically related. Southern hybridization with a nifHD gene probe to the blotted field inversion electrophoresis gels provided further evidence of the relatedness between members of serogroups 123 and 127.