DIFFERENTIATION OF INTESTINAL SPIROCHETES BY MULTILOCUS ENZYME ELECTROPHORESIS ANALYSIS AND 16S RIBOSOMAL-RNA SEQUENCE COMPARISONS

Multilocus enzyme electrophoresis (MEE) analysis and comparisons of ne arly complete 16S rRNA gene sequences (1416 nucleotide positions) were used to evaluate phylogenetic relationships among Serpulina hyodysent eriae strain, B78(T), S. innocens strain B256(T), Brachyspira Aalborgi strain 513A(T), and eight uncharacterised strains of swine, avian, an d human intestinal spirochaetes, From MEE analysis, nine strains could be assigned to five groups containing other intestinal spirochaetes ( genetic distances between groups = 0.6-0.9). Chicken spirochaete strai n C1 and B. aalborgi 513A(T) represented unique electrophoretic types and formed their own MEE groups. Despite MEE differences, the 11 strai ns had highly similar (96.3-99.9%) 165 rRNA sequences. These findings point out limitations of both MEE analysis and 16S rRNA sequence compa risons when used as solitary techniques for classifying intestinal spi rochaetes related to Brachyspira/Serpulina species.