PHENOTYPIC AND PHYLOGENETIC DESCRIPTION OF AN ITALIAN ISOLATE OF MICROTHRIX PARVICELLA

''Microthrix parvicella'' strain RN1 was isolated from an activated sl udge 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 o f the 16S rDNA which was amplified directly from cell biomass by the p olymerase chain reaction and sequenced. ''Microthrix parvicella'' stra in RN1 presents a very high similarity (100%) with another ''M. parvic ella'' strain recently isolated in Australia, suggesting that this mic ro-organism, a novel, deep branching member of the actinomycetes subph ylum, is the causing the common events of bulking and foaming phenomen a in activated sludge treatment plants throughout the world.