title: Characterization of freshwater benthic biofilm-forming Hydrocoryne (Cyanobacteria) isolates from Antarctica.
abstract: The aims of this work were to study cyanobacterial isolates resembling the genus Hydrocoryne using a combination of morphology and phylogeny of 16S rRNA and nifH sequences and to investigate genes involved in cyanotoxin and protease inhibitor production. Four new cyanobacterial strains, isolated from biofilm samples collected from King George Island, Antarctica, were studied. In terms of morphology, these new strains share traits similar to true Anabaena morphotypes (benthic ones), whereas phylogenetic analysis of their 16S rRNA gene sequences grouped them with the sequence of the type species Hydrocoryne spongiosa (H. Schwabe ex Bornet and Flahault 1886-1888), but not with sequences of the type species from the genus Anabaena. This cluster is the sister group of Anabaena morphotypes isolated only from the Gulf of Finland. In addition, this cluster is related to two other clusters formed by sequences of Anabaena isolated from different sites. Partial nifH genes were sequenced from two strains and the phylogenetic tree revealed that the Antarctic nifH sequences clustered with sequences from Anabaena. Furthermore, two strains were tested, using PCR with specific primers, for the presence of genes involved in cyanotoxins (microcystin and saxitoxin) and protease inhibitor (aeruginosin, and cyanopeptolin). Only cyanopeptolin was amplified using PCR. These four Hydrocoryne strains are the first to be isolated and sequenced from Antarctica, which improves our knowledge on this poorly defined cyanobacterial genus.
authors.affiliation: Center for Nuclear Energy in Agriculture, University of São Paulo, Avenida Centenário 303, Piracicaba, São Paulo, 13400-970, Brazil.
authors.forename: Diego Bonaldo
authors.initials: DB
authors.lastname: Genuário
authors.affiliation: Botany Department, Federal University of Viçosa, Avenida Peter Henry Rolfs, s/n, Viçosa, Minas Gerais, 36570-000, Brazil.
authors.forename: Débora Machado
authors.initials: DM
authors.lastname: Corrêa
authors.affiliation: Institute of Botany, Czech Academy of Sciences, Dukelská 135, Třeboň, CZ-37982, Czech Republic.|Faculty of Science, University of South Bohemia, Branišovská 35, České Budějovice, CZ-37005, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Komárek
authors.affiliation: Center for Nuclear Energy in Agriculture, University of São Paulo, Avenida Centenário 303, Piracicaba, São Paulo, 13400-970, Brazil.
authors.forename: Marli Fátima
authors.initials: MF
authors.lastname: Fiore
keywords: 16S rRNA; Anabaena; Phylogeny; Polar freshwater; nifH gene