Phenotypic and phylogenetic description of an Italian isolate of "Microthrix parvicella".

"Microthrix parvicella" strain RN1 was isolated from an activated sludge treatment plant in Italy using micromanipulation techniques. The strain grows as thin unbranchedfilaments which are Gram-positive with Neisser-positive granules. The isolate was characterized by analysis of the 16S rDNA which was amplified directly from cell biomass by the polymerase chain reaction and sequenced. "Microthrix parvicella" strain RN1 presents a very high similarity (100%) with another "M. parvicella" strain recently isolated in Australia, suggesting that this micro-organism, a novel, deep branching member of the actinomycetes subphylum, is the same causing the common events of bulking and foaming phenomena in activated sludge treatment plants throughout the world.