CONSTRUCTION OF A FIBROBACTER-SUCCINOGENES GENOMIC MAP AND DEMONSTRATION OF DIVERSITY AT THE GENOMIC LEVEL

The genomic cleavage map of the type strain Fibrobacter succinogenes S 85 was constructed. The restriction enzymes Asci, AvrII, FseI, NofI, a nd SfiI generated DNA fragments of suitable size distribution that cou ld be resolved by pulsed-field gel electrophoresis (PFGE). An average genome size of 3.6 Mb was obtained by summing the total fragment sizes . The linkages between the 15 AscI fragments of the genome were determ ined by combining two approaches: isolation of linking clones and cros shybridization of restriction fragments. The genome of F. succinogenes was found to be represented by the single circular DNA molecule. Sout hern hybridization with specific probes allowed the eight genetic mark ers to be located on the restriction map. The genome of this bacterium contains at least three rRNA operons. PFGE of the other three strains of F. succinogenes gave estimated genome sizes close to that of the t ype strain. However, RFLP patterns of these strains generated by Asci digestion are completely different. Pairwise comparison of the genomic fragment distribution between the type strain and the three isolates showed a similarity level in the region of 14.3% to 31.3%. No fragment common to all of these F: succinogenes strains could be detected by P FGE, A marked degree of genomic heterogeneity among members of this sp ecies makes genomic III;LP a highly discriminatory and useful molecula r typing tool for population studies.