Preliminary characterization of a tentatively novel rumen bacterial species from the genus Treponema

A new spirochetal strain was isolated from the rumen of a black-and-white H olstein cow and preliminarily characterized. The sugar fermentation tests a nd morphological observations indicated this organism to be a member of a n ovel, as yet undescribed spirochetal rumen species, The small subunit ribos omal RNA genes were amplified and the PCR products were cut with the restri ction endonucleases TaqI, DdeI, HhaI and Sau3Al. The comparison of the obse rved RFLP with the hypothetical fragment lengths of the computer analyzed 1 6S rRNA sequences from the type strains of the ruminal spirochetes Treponem a bryantii and T saccharophilum confirmed the tentative novel identificatio n. Transmission electron microscopy showed that the bacterium has the typic al spirochetal structures, i.e, the outer sheath, the protoplasmic cylinder and the axial filament (it is not yet clear how many flagella compose the filament). An additional extracellular structure was observed which appeare d as an exocytoplasmic polar flagellum, approximately 2 mum long and protru ding from one tip of the cell. The average size of the cells was 0.5 x 10-1 5 mum and the wavelengths and the amplitudes of the primary coils were 2.9 and 1.3 mum. respectively.