title: Genotypic and phenotypic analysis of strains assigned to the widespread cyanobacterial morphospecies Phormidium autumnale (Oscillatoriales).
abstract: In this study, ten cyanobacterial strains assigned to the oscillatorian species Phormidium autumnale have been characterized using a polyphasic approach by comparing phenotypic and molecular characteristics. The phenotypic analysis dealt with cell and filament morphology, ultrastructure, and pigment content. The molecular phylogenetic analyses were based on sequences of the 16S rRNA gene and the adjacent intergenic transcribed spacer (ITS). The strains were quite homogenous in their morphologic features. Their thylakoids showed a stacked or fascicular pattern. Some, but not all strains contained phycoerythrin. Only one strain (P. autumnale UTCC 476) deviated significantly in its phenotype by lacking a calyptra. In neighbour-joining and maximum Parsimony trees most 16S rRNA sequences were located on a single well-defined branch, which, however, also harboured sequences assigned to other cyanobacterial genera. Two strains (P. autumnale UTCC 476 and P. autumnale UTEX 1580) were found on distant branches. The presence of phycoerythrin was not correlated with the strains' position in the phylogenetic trees. Our results reconfirm that the morphospecies P. autumnale and the Phormidium group in general are not phylogenetically coherent and require revision. However, as indicated by sequence similarities most of the strains assigned to P. autumnale except P. autumnale UTCC 476 and P. autumnale UTEX 1580 are phylogenetically related and might belong to a single genus.
authors.affiliation: Department of Geomicrobiology, ICBM, Carl von Ossietzky University of Oldenburg, Carl-von-Ossietzky-Str., 9-11, 26111, Oldenburg, Germany. k.palinska@uni-oldenburg.de
authors.forename: Katarzyna A
authors.initials: KA
authors.lastname: Palinska
authors.forename: Jürgen
authors.initials: J
authors.lastname: Marquardt
mesh_terms: D000458:Cyanobacteria / Q000737:chemistry* / Q000145:classification* / Q000235:genetics / Q000648:ultrastructure; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D005838:Genotype; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D010860:Pigments, Biological / Q000737:chemistry; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D010860:Pigments, Biological; D012336:RNA, Ribosomal, 16S