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DIVERSITY OF 16S rDNA RESTRICTION FRAGMENT LENGTH POLYMORPHISM PROFILES OF BACTEROIDES FRAGILIS GROUP SPECIES ISOLATED FROM HUMAN AND MARMOSETS.

Santos, A*; Abdo, MCB; Anacleto C; Branco, KMGR; Pestana, ACNR; Farias, LM; Carvaiho, MAR; Moreira, ESA; Petrillo-Peixoto, ML.
Department of Microbiology, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.

To evaluate the genotipic diversity among several strains ofthe Bacteroides fragilis group isolate from human and non human primates, a 1.5 kb 16S rDNA fragment obtained by PCR, using a forward E. coli universal primer and a B. fragilis selective reverse primer was used as probe for Southern blots of genomic DNAs. Thirteen reference strains of the 10 recognized species of Bacteroides as well as Brazilian isolates (Belo Horizonte, Minas Gerais) from humans and marmosets were examined. All the Brazilian isolates were identified at the specie level based on conventional biochemical characteristics. Using the restriction endonucleases HindIII, EcoRI, PstI and BamHI that cut DNA from this bacterial group relatively infrequently, several bands with molecular size from 1.5 to 20 kb hybridized to the probe. The autoradiographs also revealed different fragment profiles for each of the reference strains. The enzyme EcoRI was used for further analyses. As the EcoRI does not have internal restriction sites on the 16S rDNA amplified fragment, the variable number of bands observed indicates that the number of operons in the genome ranged from three to seven among the ten species of the B. fragilis group. Restriction fragment length polymorphisms were observed for many of the isolates examined, indicating a marked heterogeneity on the Bacteroides species. The data obtained until this moment indicate that rDNA RFLPs might be a useful taxonomic tool for distinction of the subtypes of Bacteroides species.

Supported by FAPEMIG and CNPq. ABSTRACT FORM