Identification of heterotrophic nanoflagellates by restriction fragment length polymorphism analysis of small subunit ribosomal DNA

Thirty clones derived from twenty isolates of heterotrophic nanoflagellates originating from a variety of marine and freshwater environments were exam ined by restriction fragment length polymorphism analysis of small subunit ribosomal RNA genes amplified by the polymerase chain reaction (riboprintin g). The data were compared with light and electron microscopical identifica tion of the isolates. On morphological criteria, sixteen of the thirty clon es belonged to the genus Paraphysomonas De Saedeleer, seven to the genus Sp umella Cienkowski, four to the genus Pteridomonas Penard and three to the g enus Cafeteria Fenchel and Patterson. Among these tars, eleven ribotypes we re detected by analysis with the restriction enzymes Hinf I, Hae III, Sau3A I, and Msp I. T. Differentiation of nanoflagellate taxa by the riboprintin g method supported taxonomic classification based on morphology at the gene ric and species level. The utility of the method for discriminating the 'na ked' flagellates and for confirming the identity of polymorphic forms among species of Paraphysomonas is demonstrated.