16S RDNA SEQUENCE AND PHYLOGENETIC POSITION OF AN UNCULTIVATED SPIROCHETE FROM THE HINDGUT OF THE TERMITE MASTOTERMES DARWINIENSIS FROGGATT

We have analyzed the 16S rDNA sequence and the phylogenetic position o f an uncultivated spirochete from the hindgut contents of the Australi an termite Mastotermes darwiniensis Froggatt. The 16S rRNA genes of ba cteria from the hindgut contents of Mastotermes darwiniensis were ampl ified by polymerase chain reaction. The amplification products were cl oned and sequenced. The sequences were compared to known homologous pr imary structures. Two of the clones (MDS1 and MDS3) had an insert of 1 498 nucleotides showing typical signatures of spirochete 16S rRNA sequ ences. The sequences of the two clones were most similar to the 16S rR NA sequence of Spirochaeta stenostrepta (89.8%) and Treponema sp. stra in H1 (90.7%). Phylogenetical analysis positioned the hindgut spiroche te sequence with that of the free-living anaerobic Spirochaeta stenost repta and Treponema sp. strain H1 as its nearest relatives within the cluster of the spirochetes. We conclude that the analyzed SSU rDNA seq uences originate from a spirochete related to the genus Treponema. It is possibly one of the uncultivated unique spirochetes symbiotic in te rmite hindguts.