Cyanobacteria
Identity of Cyanobacterial Toxins
Cyanobacterial toxins are toxins produced by cyanobacteria, or blue-green algae. They include neurotoxins (e.g., anatoxins), hepatotoxins (e.g., microcystins), skin irritants and other toxins. Both hepatotoxins and neurotoxins are produced by cyanobacteria commonly found in surface water supplies and therefore appear to be of most relevance to water supplies at present.1-3 However, the neurotoxins are relatively unstable and, as such, are not considered to be as widespread as hepatotoxins in water supplies; in addition, they do not appear to pose the same degree of risk from chronic toxicity.3 It should be noted, however, that, due to limited analytical capabilities, there are only limited quantitative data available on the levels of neuro-toxins in water supplies. Cyanobacterial toxins were detected during a survey in the summer (July/August) of 2000 in Onondaga Lake and Oneida Lake in upstate New York, USA.4Microcystins were detected in only one of 13 samples from Onondaga Lake, as was anatoxin-a. However, 50% of the 22 samples from Oneida Lake tested positive for microcystins (seven or eight tested >1.0 µg/L), and two samples were positive for anatoxin-a. Anatoxin-a was less common than microcystins, with levels -0.85 µg/L. It may be possible that neurotoxins are more widespread than is currently believed, particularly since many of the neurotoxin-producing algae have been linked to deaths of both livestock and domestic animals.
Most of the hepatotoxins are collectively referred to as microcystins, because the first hepatotoxin was isolated from Microcystis aeruginosa. About 50 different microcystins have been isolated, and several of these may be produced during a bloom. Structurally, the microcystins are monocyclic heptapeptides that contain two variable L-amino acids and two novel D-amino acids. Microcystins are named according to their variable L-amino acids -- for example, microcystin-LR contains leucine (L) and
Cyanobacterial toxins are toxins produced by cyanobacteria, or blue-green algae. They include neurotoxins (e.g., anatoxins), hepatotoxins (e.g., microcystins), skin irritants and other toxins. Both hepatotoxins and neurotoxins are produced by cyanobacteria commonly found in surface water supplies and therefore appear to be of most relevance to water supplies at present.1-3 However, the neurotoxins are relatively unstable and, as such, are not considered to be as widespread as hepatotoxins in water supplies; in addition, they do not appear to pose the same degree of risk from chronic toxicity.3 It should be noted, however, that, due to limited analytical capabilities, there are only limited quantitative data available on the levels of neuro-toxins in water supplies. Cyanobacterial toxins were detected during a survey in the summer (July/August) of 2000 in Onondaga Lake and Oneida Lake in upstate New York, USA.4Microcystins were detected in only one of 13 samples from Onondaga Lake, as was anatoxin-a. However, 50% of the 22 samples from Oneida Lake tested positive for microcystins (seven or eight tested >1.0 µg/L), and two samples were positive for anatoxin-a. Anatoxin-a was less common than microcystins, with levels -0.85 µg/L. It may be possible that neurotoxins are more widespread than is currently believed, particularly since many of the neurotoxin-producing algae have been linked to deaths of both livestock and domestic animals.
Most of the hepatotoxins are collectively referred to as microcystins, because the first hepatotoxin was isolated from Microcystis aeruginosa. About 50 different microcystins have been isolated, and several of these may be produced during a bloom. Structurally, the microcystins are monocyclic heptapeptides that contain two variable L-amino acids and two novel D-amino acids. Microcystins are named according to their variable L-amino acids -- for example, microcystin-LR contains leucine (L) and