Toxicity and genetic diversity of Cylindrospermopsis raciborskii in Florida, USA

Abstract

Cylindrospermopsis raciborskii is a potentially toxic cyanobacterium which has become increasingly prominent in algal blooms throughout the USA. Twenty strains of C. raciborskii isolated from Florida, and one strain from Indiana (USA), were tested for the ability to produce three toxins, cylindrospermopsin, microcystin and saxitoxin using newly developed Polymerase Chain Reaction (PCR) primers and Enzyme Linked Immunosorbent Assays (ELISA). None of these strains demonstrated the ability to produce any of the three toxins. Phylogenetic analyses of 16S rRNA gene sequences, a common genetic marker used in taxonomic differentiation, did not delineate these isolates from other C. raciborskii strains. However, Rubisco Large Subunit gene sequences, a less commonly used but useful genetic marker, provided better resolution of differences between Florida strains of C. raciborskii and those from Australia, which are known to be toxic. There may be toxic strains of C. raciborskii in the USA, but none were found among the Florida and Indiana strains examined, suggesting that strains of C. raciborskii in Florida lakes, and perhaps other regions of North America, may not be toxic. The potential management implications of this observation warrant further exploration of the toxicity of this species in the Americas.