TITLE	Molecular phylogeny of nitrogen-fixing unicellular cyanobacteria
AUTHOR	Sean Turner Department of Biology, Indiana University, Bloomington, Indiana 47405-3700, USA Tan-Chi Huang Institute of Botany, Academia Sinica, Taipei 115, Taiwan Shu-Miaw Chaw Institute of Botany, Academia Sinica, Taipei 115, Taiwan
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ABSTRACT	Molecular phylogenetic study was conducted using maximum likelihood tree inference methods with small subunit ribosomal RNA sequence data to ascertain the evolutionary relationships among sheathless, single-cell cyanobacteria capable of nitrogen fixation. Cyanobacterial strains of the genus Cyanothece (circumscribed by Waterbury and Rippka, 1989) fall into at least three independent lines of descent within a larger assemblage previously designated the SPM sequence group. No strong correlation between aerobic versus anaerobic nitrogen-fixing activity and phylogenetic relationships was observed. The results support a hypothesis of multiple gains and/or losses of nitrogen-fixation abilities among the sheathless, unicellular cyanobacteria.
KEYWORD	Aerobic; Anaerobic; Cyanobacteria; Nitrogen fixation; Phylogeny; Ribosomal RNA; Sheathless; Small subunit;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 42 Number 3 July 2001, page 181-186, 6 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China