Toxicity of the cyanobacterium Limnothrix AC0243 to male Balb/c mice

A growing list of freshwater cyanobacteria are known to produce toxic agents, a fact which makes these organisms of concern to water authorities. A cultured strain of Limnothrix (AC0243) was recently shown to have toxic effects in in vitro bioassays. It did not produce any of the known cyanobacterial toxins. The intrapertoneal toxicity of aqueous extracts of the material was therefore tested in mice to determine whether the observed effects might be of public health relevance to drinking water supplies. The results indicate that Limnothrix AC0243 is acutely toxic to mice, causing widespread cellular necrosis in the liver, kidneys and gastrointestinal tract within 24 h of exposure. Sub-lethal effects lasted at least 7 d. These results suggest that Limnothrix AC0243 produces a novel toxin ("Limnothrixin") and that further work is therefore urgently required to quantify the potential public health implications.

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► The cyanobacterial genus Limnothrix is shown for the first time to be toxic.
► The toxic effects in mice are dissimilar to those of known cyanobacterial toxins.
► Tissue injury was widespread, including in the GI tract, liver, kidneys and lungs.
► The toxin is extractable into water, indicating a potential risk to potable water.