title: First report of saxitoxin production by a species of the freshwater benthic cyanobacterium, Scytonema Agardh.
abstract: Saxitoxins or paralytic shellfish poisons (PSP) are neurotoxins produced by some species of freshwater cyanobacteria and marine dinoflagellates. Samples collected from the metaphyton of a drinking-water supply's pre-treatment reservoir and a small eutrophic lake in New Zealand returned positive results when screened using a Jellett PSP Rapid Test Kit. The dominant species in the sample was identified as Scytonema cf. crispum. A non-axenic clonal culture (UCFS10) was isolated from the lake. The partial 16S rRNA gene sequence shared only a 91% or less sequence similarity with other Scytonema species, indicating that it is unlikely that this genus is monophyletic and that further in-depth phylogenetic re-evaluation is required. The sxtA gene, which is known to be involved in saxitoxin production, was detected in UCFS10. Saxitoxin concentrations were determined from the lake samples and from UCFS10 using pre-column oxidation high performance liquid chromatography with fluorescence detection. Saxitoxin was the only variant detected and this was found at concentrations of 65.6 μg g⁻¹ dry weight in the lake sample and 119.4 μg g⁻¹ dry weight or 1.3 pg cell⁻¹ in UCFS10. This is the first confirmation of a saxitoxin-producing species in New Zealand and the first report of saxitoxin production by a species of Scytonema.
authors.affiliation: Department of Chemistry, Canterbury University, Private Bag 4800, Christchurch 8140, New Zealand. Francine.Smith@pg.canterbury.ac.nz
authors.forename: Francine M J
authors.initials: FM
authors.lastname: Smith
authors.forename: Susanna A
authors.initials: SA
authors.lastname: Wood
authors.forename: Roel
authors.initials: R
authors.lastname: van Ginkel
authors.forename: Paul A
authors.initials: PA
authors.lastname: Broady
authors.forename: Sally
authors.initials: S
authors.lastname: Gaw
mesh_terms: D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004784:Environmental Monitoring; D005618:Fresh Water; D009520:New Zealand; D011042:Poisons / Q000032:analysis / Q000378:metabolism*; D012329:RNA, Bacterial / Q000032:analysis; D012530:Saxitoxin / Q000032:analysis / Q000378:metabolism*; D017423:Sequence Analysis, RNA; D057096:Shellfish Poisoning; D014871:Water Microbiology
chemical_list: D011042:Poisons; D012329:RNA, Bacterial; D012530:Saxitoxin