title: Culture-independent evidence for the persistent presence and genetic diversity of microcystin-producing Anabaena (Cyanobacteria) in the Gulf of Finland.
abstract: The late summer mass occurrences of cyanobacteria in the Baltic Sea are among the largest in the world. These blooms are rarely monotypic and are often composed of a diverse assemblage of cyanobacteria. The toxicity of the blooms is attributed to Nodularia spumigena through the production of the hepatotoxic nodularin. However, the microcystin hepatotoxins have also been reported from the Baltic Sea on a number of occasions. Recent evidence links microcystin production in the Gulf of Finland directly to the genus Anabaena. Here we developed a denaturing gradient gel electrophoresis (DGGE) method based on the mcyE microcystin synthetase gene and ndaF nodularin synthetase gene that allows the culture-independent discrimination of microcystin- and nodularin-producing cyanobacteria directly from environmental samples. We PCR-amplified microcystin and nodularin synthetase genes from environmental samples taken from the Gulf of Finland and separated them on a denaturing gradient gel using optimized conditions. Sequence analyses demonstrate that uncultured microcystin-producing Anabaena strains are genetically more diverse than previously demonstrated from cultured strains. Furthermore, our data show that microcystin-producing Anabaena are widespread in the open Gulf of Finland. Non-parametric statistical analysis suggested that salinity plays an important role in defining the distribution of microcystin-producing Anabaena. Our results indicate that microcystin-producing blooms are a persistent phenomenon in the Gulf of Finland.
authors.affiliation: Department of Applied Chemistry and Microbiology, PO Box 56, Viikki Biocenter, Viikinkaari 9, FIN-00014, University of Helsinki, Finland.
authors.forename: David P
authors.initials: DP
authors.lastname: Fewer
authors.forename: Miikka
authors.initials: M
authors.lastname: Köykkä
authors.forename: Katrianna
authors.initials: K
authors.lastname: Halinen
authors.forename: Jouni
authors.initials: J
authors.lastname: Jokela
authors.forename: Christina
authors.initials: C
authors.lastname: Lyra
authors.forename: Kaarina
authors.initials: K
authors.lastname: Sivonen
mesh_terms: D017033:Anabaena / Q000145:classification* / Q000302:isolation & purification* / Q000378:metabolism; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005387:Finland; D014644:Genetic Variation; D052998:Microcystins / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D052998:Microcystins; C078588:microcystin