PHYLOGENETIC POSITION OF RIEMERELLA ANATIPESTIFER BASED ON 16S RIBOSOMAL-RNA GENE-SEQUENCES

Riemerella anatipestifer; the causative agent of septicemia anserum ex sudativa (also called new duckling disease), belongs to the family Fla vobacteriaceae of gram-negative bacteria. We determined the DNA sequen ces of the ns genes encoding the 16S rRNAs of four X. anatipestifer st rains by directly sequencing PCR-amplified rrs genes. A sequence simil arity analysis confirmed the phylogenetic position of R. anatipestifer in the family Flavobacteriaceae in rRNA superfamily V and allowed fin e mapping of R. anatipestifer on a separate rRNA branch comprising the most closely related species, Bergeyella zoohelcum, as well as Chryse obacterium balustinum, Chryseobacterium indologenes, and Chryseobacter ium gleum. The sequences of the rrs genes of the four R. anatipestifer strains varied between 0.5 and 1,0%, but all of the strains occupied the same position on the phylogenetic tree. In general, differences in rrs genes were observed among X. anatipestifer strains, even within a given serotype, as shown by restriction fragment length polymorphism of PCR-amplified rrs genes.