Genotypic and phenotypic diversity of cyanobacteria assigned to the genus Phormidium (Oscillatoriales) from different ha
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O RI G I NAL PAPE R
Genotypic and phenotypic diversity of cyanobacteria assigned to the genus Phormidium (Oscillatoriales) from diVerent habitats and geographical sites Jürgen Marquardt · Katarzyna A. Palinska
Received: 11 May 2006 / Revised: 23 November 2006 / Accepted: 28 November 2006 / Published online: 21 December 2006 © Springer-Verlag 2006
Abstract In this study, 30 strains of Wlamentous, nonheterocystous cyanobacteria from diVerent habitats and diVerent geographical regions assigned to diverse oscillatorian genera but here collectively referred to as members of the Phormidium group have been characterized using a polyphasic approach by comparing phenotypic and molecular characteristics. The phenotypic analysis dealt with cell and Wlament morphology, ultrastructure, phycoerythrin content, and complementary chromatic adaptation. The molecular phylogenetic analyses were based on sequences of the 16S rRNA gene and the adjacent intergenic transcribed spacer (ITS). The sequences were located on multiple branches of the inferred cyanobacterial 16S rRNA tree. For some, but not all, strains with identical 16S rDNA sequences, a higher level of discrimination was achieved by analyses of the less conserved ITS sequences. As shown for other cyanobacteria, no correlation was found between position of the strains in the phylogenetic tree and their geographic origin. Genetically similar strains originated from distant sites while other strains isolated from the same sampling site were in diVerent phylogenetic clusters. Also the presence of phycoerythrin was not correlated with the strains’ position in the phylogenetic trees. In contrast, there was some correlation among inferred phylogenetic relationship, original environmental habitat, and morphology. Closely related strains came from similar
J. Marquardt · K. A. Palinska (&) Geomicrobiology, ICBM, Carl von Ossietzky University of Oldenburg, Carl-von-Ossietzky-Str. 9–11, 26111 Oldenburg, Germany e-mail: [email protected]
ecosystems and shared the same morphological and ultrastructural features. Nevertheless, structural properties are insuYcient in themselves for identiWcation at the genus or species level since some phylogenetically distant members also showed similar morphological traits. Our results reconWrm that the Phormidium group is not phylogenetically coherent and requires revision. Keywords Cyanobacteria · Oscillatoriales · Phormidium · Phylogeny · Taxonomy
Introduction The genus Phormidium Kützing 1843 has been used to encompass widely diverse morphotypes. For the Oscillatoriacean cyanobacteria, including those discussed in this communication, Maurice Gomont’s Monographie des Oscillatoriées (Gomont 1892) is usually considered the earliest comprehensive source for their taxonomic classiWcation. Gomont’s scheme was followed with minor modiWcations by Geitler (1932), Frémy (1934), Elenkin (1949), Desikachary (1959), Starmach (1966) and Umezaki (1961). The criteria traditionally prescribed for classiWcation of genera in Oscillatoriaceae relied predomin
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