NUMBER AND HETEROGENEITY OF rRNA OPERONS IN RUMEN BACTERIAL MEMBERS FROM THE GENUS Prevotella

The number of rRNA operons and internal spacer region heterogeneities in members of the rumen genus Prevotella were analysed. Chromosomal DNA from 20 strains belonging to P.ruminicola, P.albensis, P.bryanti and P.brevis was isolated, digested by five restriction enzymes, and hybridized with 16S and 23S rDNA probes. The resulting hybridization patterns indicate that P. albensis strains possess 4 or 5 rRNA operons, strains belonging to P. brevis possess 4 rRNA operons and P. bryantii strains 6 or 7 rRNA operons. Strains belonging to P. ruminicola probably possess 4 rRNA operons, with one exception having 6 or 7 rRNA operons. 16S-23S spacer region was also PCR amplified. The results suggest that there are at least three size variable 16S-23S spacer regions in P. albensis and P. brevis, two in P. ruminicola, and only one spacer region in P. bryantii.