Characterization of genomic architecture of Rhizobium sp. strains. (A) Plasmid profiles. (B) PFGE of undigested genomic DNA stained by ethidium bromide. (C to E) Autoradiographs of blotted PFGE hybridized against replicon-specific probes: 16S RNA gene probe for the chromosome (C), exopolysaccharide gene probe for pNGR234b (D), and nitrogenase gene probe for pNGR234a (E). Lanes: Sm, S. meliloti strain 1021; 1 and 6, wild-type strain NGR234; 2, CFNX401; 3, CFNX407; 4, CFNX408; and 5, CFNX416. The position of each replicon is indicated in the wild-type strain: x, pNGR234a; y, pNGR234b; and z, chromosome.