Small subunit rDNA phylogeny of Bacillidium sp. (Microspora, Mrazekiidae) infecting oligochaets.

Small subunit (SSU) rDNA has been sequenced from a microsporidium, identified as a member of the genus Bacillidium obtained from an oligochaete. The length of the amplified PCR product was 1386 bp which is currently the longest microsporidium SSU sequence known. Phylogenetic analysis using 28 microsporidia SSU sequences, using 3 different tree-building methods indicated that Bacillidium sp. may be one of the earliest branches on the microsporidia tree. However, bootstrapping failed to give a high score (more than 50%) for the position of Bacillidium sp. The branch leading to Bacillidium sp. was long, indicating that this species is not closely related to any of the other microsporidia so far studied by means of rDNA.