Trichodesmium erythraeum IMS101
Marine filamentous cyanobacteria of the genus Trichodesmium play a major role in the tropical and subtropical oceans both as primary producers and suppliers of "new" nitrogen through their ability to fix atmospheric dinitrogen (N2) (Capone et al., 1997). They are simple undifferentiated filamentous forms that divide in a single plane. They may occur as single filaments but more commonly as macroscopic colonial aggregates (0.3-2mm) containing many filaments. The colonies vary in color from yellowish-brown to deep red because they contain phycoerythrin as their primary light harvesting pigment. Trichodesmium spp. are planktonic and owe their buoyancy to the possession of gas vacuoles. The genus currently contains five species characterized from natural populations (Carpenter et al., 1993; Janson et al., 1995). The species are distinguished by cell and colony morphology, pigmentation and buoyancy.