title: Variation between strains of the cyanobacterium Microcystis aeruginosa isolated from a Portuguese river.
abstract: OBJECTIVE
  The aim of this study was to investigate toxicological differences between strains of the cyanobacterium Microcystis aeruginosa isolated from a potable water supply in the north of Portugal over a 2-month period.
  
  
  RESULTS
  Twenty-six strains of M. aeruginosa were isolated, grown in pure culture, and tested using a range of techniques including matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), ELISA and a PCR procedure targeting the genes implicated in the production of toxic microcystins. There was considerable variation with respect to the amounts of microcystin produced by each of the strains as measured by ELISA, with values ranging from 0.02 to 0.53% dry weight. The results of the MALDI-TOF MS analysis demonstrated the presence of several chemically distinct forms of microcystin as well as aeruginosins, anabaenopeptins and several other unidentified peptide-like compounds.
  
  
  CONCLUSIONS
  The growth of individual strains that comprise bloom populations, with unique 'chemotypes' can potentially be an important factor affecting the toxicity of bloom populations. Molecular probes, targeting the genes responsible for microcystin production were shown to be useful for distinguishing between toxic and nontoxic strains and showed good agreement with the results obtained from the other analyses.
  
  
  CONCLUSIONS
  The results of this study show that the analysis of cyanobacterial bloom populations at the subspecies (strain) level can potentially provide important information regarding the toxin-producing potential of a cyanobacterial bloom and could be used as an 'early warning' for toxic bloom development.
authors.affiliation: Centro Interdisciplinar de Investigação Marinha e Ambiental, Porto, Portugal. martinsaker@hotmail.com
authors.forename: M L
authors.initials: ML
authors.lastname: Saker
authors.forename: J
authors.initials: J
authors.lastname: Fastner
authors.forename: E
authors.initials: E
authors.lastname: Dittmann
authors.forename: G
authors.initials: G
authors.lastname: Christiansen
authors.forename: V M
authors.initials: VM
authors.lastname: Vasconcelos
mesh_terms: D001427:Bacterial Toxins / Q000032:analysis; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D004791:Enzyme Inhibitors / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D052998:Microcystins; D046931:Microcystis / Q000302:isolation & purification / Q000502:physiology*; D009842:Oligopeptides / Q000032:analysis; D010455:Peptides / Q000032:analysis; D010456:Peptides, Cyclic / Q000032:analysis; D016133:Polymerase Chain Reaction / Q000379:methods; D045483:Rivers / Q000382:microbiology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D014871:Water Microbiology
chemical_list: D001427:Bacterial Toxins; D003470:Culture Media; D004269:DNA, Bacterial; D004791:Enzyme Inhibitors; D052998:Microcystins; D009842:Oligopeptides; D010455:Peptides; D010456:Peptides, Cyclic; C078588:microcystin