title: Community composition, toxigenicity, and environmental conditions during a cyanobacterial bloom occurring along 1,100 kilometers of the Murray River.
abstract: A cyanobacterial bloom impacted over 1,100 km of the Murray River, Australia, and its tributaries in 2009. Physicochemical conditions in the river were optimal to support a bloom at the time. The data suggest that at least three blooms occurred concurrently in different sections of the river, with each having a different community composition and associated cyanotoxin profile. Microscopic and genetic analyses suggested the presence of potentially toxic Anabaena circinalis, Microcystis flos-aquae, and Cylindrospermopsis raciborskii at many locations. Low concentrations of saxitoxins and cylindrospermopsin were detected in Anabaena and Cylindrospermopsis populations. A multiplex quantitative PCR was used, employing novel oligonucleotide primers and fluorescent TaqMan probes, to examine bloom toxigenicity. This single reaction method identified the presence of the major cyanotoxin-producing species present in these environmental samples and also quantified the various toxin biosynthesis genes. A large number of cells present throughout the bloom were not potential toxin producers or were present in numbers below the limit of detection of the assay and therefore not an immediate health risk. Potential toxin-producing cells, possessing the cylindrospermopsin biosynthesis gene (cyrA), predominated early in the bloom, while those possessing the saxitoxin biosynthesis gene (sxtA) were more common toward its decline. In this study, the concentrations of cyanotoxins measured via enzyme-linked immunosorbent assay (ELISA) correlated positively with the respective toxin gene copy numbers, indicating that the molecular method may be used as a proxy for bloom risk assessment.
authors.affiliation: Address correspondence to Brett A. Neilan, b.neilan@unsw.edu.au.
authors.forename: Jamal
authors.initials: J
authors.lastname: Al-Tebrineh
authors.forename: Chester
authors.initials: C
authors.lastname: Merrick
authors.forename: David
authors.initials: D
authors.lastname: Ryan
authors.forename: Andrew
authors.initials: A
authors.lastname: Humpage
authors.forename: Lee
authors.initials: L
authors.lastname: Bowling
authors.forename: Brett A
authors.initials: BA
authors.lastname: Neilan
mesh_terms: D000470:Alkaloids; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D058448:Biota; D000458:Cyanobacteria / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D000087522:Cyanobacteria Toxins; D004269:DNA, Bacterial / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay; D052998:Microcystins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009517:New South Wales; D010456:Peptides, Cyclic / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D045483:Rivers / Q000737:chemistry / Q000382:microbiology*; D012530:Saxitoxin / Q000235:genetics / Q000378:metabolism; D014498:Uracil / Q000031:analogs & derivatives / Q000378:metabolism; D014739:Victoria; D014871:Water Microbiology
chemical_list: D000470:Alkaloids; D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D004269:DNA, Bacterial; D052998:Microcystins; D010456:Peptides, Cyclic; C063998:nodularin; C089595:cylindrospermopsin; D012530:Saxitoxin; D014498:Uracil; C078588:microcystin
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