PULSED-FIELD GEL ELECTROPHORESIS-FINGERPRINTING, GENOME SIZE ESTIMATION AND RRN LOCI NUMBER OF RHIZOBIUM-GALEGAE

The genomes of several Rhizobium galegae (of.) strains, which effectiv ely nodulate Galega officinalis host, were analysed by pulsed-field ge l electrophoresis (PFGE). Individual PFGE-fingerprints were obtained f or every particular strain when the rarely cutting restriction endonuc leases SpeI and AsnI were applied. In hybridization experiments, where a DNA fragment carrying the rrnB ribosomal RNA operon of Escherichia coli was used as a probe, the number of the resulting strain-specific SpeI and AsnI bands was reduced to three for all of the strains studie d. This suggests that in Rh. galegae (of.) there are at least three rr n loci. On the basis of the lengths of the SpeI fragments, separated b y PFGE, the genome size of five Rh. galegae (of.) strains was estimate d to be 5852 +/- 198 kbp.