Abstract

Planktonic cyanotoxin poisoning events are well documented. More recently, benthic cyanobacteria have also been associated with bird, cattle and dog fatalities. Extensive mats of benthic cyanobacteria can contain high concentrations of toxins. This study investigated cyanotoxin production in cyanobacterial strains isolated from benthic freshwater mats dominated by cyanobacteria in Canterbury, New Zealand. Twenty-seven strains were isolated from ten water bodies and characterized using morphological and molecular phylogenetic characteristics. All strains were screened for genes involved in the biosynthesis of common cyanotoxins. Positive results were confirmed and cyanotoxin concentrations quantified using liquid chromatography–mass spectrometry. One chroococcalean, twenty oscillatorialean and six nostocalean strains were isolated into culture. All strains were cryopreserved and banked in the Cawthron Institute Culture Collection of Micro-algae. Genes associated with anatoxin-a biosynthesis were identified in nine Phormidium strains. Anatoxin-a was detected in all these strains, one of these strains also produced homoanatoxin-a.

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