A novel Treponema species was isolated from an ulcerative lesion of a cow suffering from digital dermatitis (DD), a disease which causes painful ulcerations along the coronary band. Among other anaerobic bacteria, high numbers of spirochaetes have been regularly found in DD lesions. Here data are presented of a spirochaete isolated from a DD ulcer. By chemotaxonomy, protein analysis and comparative 16S rDNA sequence analysis this isolate was classified as a treponeme that differed from all Treponema species described previously. The only isolate, DD5/3T, for which the name Treponema brennaborense is proposed, is designated the type strain of the novel species. The strain is a small, highly motile spirochaete that has two periplasmc flagella, one flagellum being attached at each cell pole. Strain DD5/31 exhibits α-glucosidase and N-acetyl-β-glucosaminidase activity and growth is inhibited by rabbit serum. T. brennaborense was phylogenetically most closely related (89--5% 16S rRNA similarity) to Treponema maltophilum, an oral spirochaete isolated from a periodontitis patient.
Thirteen Gram-negative bacterial isolates were recovered from diseased pigeons and were tentatively classified as Riemerella anatipestifer-like strains based on conventional phenotypic features and disease symptoms. Phenotypic characteristics that differentiated the pigeon isolates from R. anatipestifer included their greyish-white to beige pigment formation on Columbia blood agar and the hydrolysis of aesculin. Furthermore, R. anatipestifer strains have thus far not been reported in pigeons. The phenotypic differences together with the unique host range of the new isolates have prompted the inclusion of these strains in a polyphasic taxonomic study. Extensive phenotypic examination, PAGE of total proteins and GC analysis of fatty acid contents revealed that the pigeon isolates constitute a homogeneous cluster, distinct from the R. anatipestifer reference strains. The phylogenetic position of representative strains was examined by using DNA-rRNA hybridizations and indicated that this taxon belongs to the genus Riemerella. Finally, DNA-binding values confirmed that the strains constitute a separate species for which the name Riemerella columbina sp. nov. is proposed. Strain LMG 11607Twas selected as the type strain. Clinical observations suggest that these organisms are involved in pathogenesis of respiratory diseases, similar to those associated with R. anatipestifer infections. However, the role of co-factors and the interaction with other agents are unknown.