Allergenicity of cyanobacteria

Article By:

Bernstein, Jonathan A. Department of Internal Medicine, Division of Immunology and Allergy Section, University of Cincinnati College of Medicine, Cincinnati, Ohio.

Bernstein, I. Leonard Department of Internal Medicine, Division of Immunology and Allergy Section, University of Cincinnati College of Medicine, Cincinnati, Ohio.

Last reviewed:2013

DOI:https://doi.org/10.1036/1097-8542.YB130092

Prokaryotic planktonic organisms are the oldest photosynthetic, oxygenic life forms that gave sharp rise to atmospheric oxygen about 2.5 billion years ago. It is estimated that they still contribute up to 30% of the yearly oxygen production on Earth. Most photosynthetic prokaryotes are single cells without a nucleus that have been classified as cyanobacteria and comprise about 165 genera and 1500 species. Although they were originally referred to as blue-green algae, their shared characteristics of bacteria better fit the modern nomenclature of cyanobacteria. Cyanobacteria are found in all illuminated environments on Earth, including hot springs, ice fields, soil, and even the fur of animals. They play key roles in the carbon and nitrogen cycles of the biosphere. Two nontoxic species, Arthrospira platensis (Spirulina) and Aphanizomenon flos-aquae, are mass produced or naturally harvested and consumed throughout the world as protein-rich nutritional supplements. However, about 40 cyanobacterial genera produce toxins, called cyanotoxins, with dermatotoxic, neurotoxic, and/or hepatotoxic properties, which have been implicated in animal and, rarely, human deaths. Because they are gram negative, they also contain lipopolysaccharide or endotoxin as a major component of their cell walls. Slight structural differences in the lipid A acyl moieties of cyanobacterial endotoxins are thought to attenuate the severe biotoxic effects caused by the endotoxins of classical gram-negative bacteria, such as Escherichia coli and Salmonella.

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