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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. |
