title: Anatoxin-a synthetase gene cluster of the cyanobacterium Anabaena sp. strain 37 and molecular methods to detect potential producers.
abstract: Cyanobacterial mass occurrences are common in fresh and brackish waters. They pose a threat to water users due to toxins frequently produced by the cyanobacterial species present. Anatoxin-a and homoanatoxin-a are neurotoxins synthesized by various cyanobacteria, e.g., Anabaena, Oscillatoria, and Aphanizomenon. The biosynthesis of these toxins and the genes involved in anatoxin production were recently described for Oscillatoria sp. strain PCC 6506 (A. Méjean et al., J. Am. Chem. Soc. 131:7512-7513, 2009). In this study, we identified the anatoxin synthetase gene cluster (anaA to anaG and orf1; 29 kb) in Anabaena sp. strain 37. The gene (81.6% to 89.2%) and amino acid (78.8% to 86.9%) sequences were highly similar to those of Oscillatoria sp. PCC 6506, while the organization of the genes differed. Molecular detection methods for potential anatoxin-a and homoanatoxin-a producers of the genera Anabaena, Aphanizomenon, and Oscillatoria were developed by designing primers to recognize the anaC gene. Anabaena and Oscillatoria anaC genes were specifically identified in several cyanobacterial strains by PCR. Restriction fragment length polymorphism (RFLP) analysis of the anaC amplicons enabled simultaneous identification of three producer genera: Anabaena, Oscillatoria, and Aphanizomenon. The molecular methods developed in this study revealed the presence of both Anabaena and Oscillatoria as potential anatoxin producers in Finnish fresh waters and the Baltic Sea; they could be applied for surveys of these neurotoxin producers in other aquatic environments.
authors.affiliation: Department of Food and Environmental Microbiology, Division of Microbiology, P.O. Box 56 (Viikinkaari 9), FI-00014 University of Helsinki, Finland.
authors.forename: Anne
authors.initials: A
authors.lastname: Rantala-Ylinen
authors.forename: Suvi
authors.initials: S
authors.lastname: Känä
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Leo
authors.initials: L
authors.lastname: Rouhiainen
authors.forename: Matti
authors.initials: M
authors.lastname: Wahlsten
authors.forename: Ermanno
authors.initials: E
authors.lastname: Rizzi
authors.forename: Katri
authors.initials: K
authors.lastname: Berg
authors.forename: Muriel
authors.initials: M
authors.lastname: Gugger
authors.forename: Kaarina
authors.initials: K
authors.lastname: Sivonen
mesh_terms: D017033:Anabaena / Q000235:genetics* / Q000378:metabolism*; D046890:Aphanizomenon / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D053898:Biosynthetic Pathways / Q000235:genetics*; D000087522:Cyanobacteria Toxins; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D023061:Gene Order; D008025:Ligases / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D054300:Oscillatoria / Q000235:genetics; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014326:Tropanes / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D000087522:Cyanobacteria Toxins; D017931:DNA Primers; D004269:DNA, Bacterial; D014326:Tropanes; C509783:anatoxin a; D008025:Ligases