MICROTHRIX PARVICELLA IS A NOVEL, DEEP BRANCHING MEMBER OF THE ACTINOMYCETES SUBPHYLUM

We have isolated the Gram-positive, straight filamentous bacterium ''M icrothrix parvicella'' from an activated sludge sewage treatment plant in Australia by using micromanipulation techniques. The 16S rDNA was amplified directly from cell biomass by the polymerase chain reaction and sequenced. This data has allowed us to phylogenetically place ''M. parvicella'' as a deep branching member of the actinomycetes subphylu m. It is most closely related to the iron-oxidising strain TH3, member s of the order Actinomycetales and to the genus Atopobium. Further phe notypic data for ''M. parvicella'' are required for the valid naming o f this organism.