The Toxic Cyanobacteria

There are an increasing number of cyanobacteria genera  and species which have been found to produce a suite of biologically active compounds. Not surprisingly, many of these compounds have proven to be very toxic to a variety of organisms including humans.  Some species of cyanobacteria are capable of producing a variety of toxic compounds although some toxins appear to be confined to specific cyanobacteria.

The cyanobacteria of concern are generally freshwater or brackish water species and are commonly found as 'blooms' in slow-flowing, nutrient-rich waters, usually in the warmer months of the year (when both temperature and sunlight are optimal). Blooms are often found in farm dams or ponds where very little mixing occurs, allowing warm water layers to form near the surface. As a result, highly toxic 'scum' material often forms on the water surface, creating a potential danger for livestock and, indeed, humans.

Below is a list of known cyanobacteria and the toxins they produce.

GenusToxins produced
AnabaenaAnatoxins, Microcystins, Saxitoxins
Anabaenopsis Microcystins
Aphanizomenon Saxitoxins, Cylindrospermopsins
Cylindrospermopsis Cylindrospermopsins, Saxitoxins
Hapalosiphon Microcystins
Lyngbya Aplysiatoxins, Lyngbyatoxin a
Microcystis Microcystins
Nodularia Nodularin
Nostoc Microcystins
Phormidium (Oscillatoria) Anatoxin
Planktothrix (Oscillatoria) Anatoxins, Aplysiatoxins, Microcystins, Saxitoxins
Schizothrix Aplysiatoxins
Trichodesmium yet to be identified
Umezakia Cylindrospermopsin

*Not all species within a genus produce the same toxins. Click on the genus name to find out more about species specific toxins. In addition to these toxins, many other bioactive compounds have been isolated from cyanobacteria. Some have been determined to be toxic to specific organisms and are potentially toxic to humans.

Supported by Biological Sciences at Purdue University and by Wichita State University