 Spirulina filaments form mats in both marine and fresh waters
or are found tangled amongst other algae or detritus. The genus
is most common in lakes rich in sodium carbonate, in bog lakes,
and on moist muds. Several species are benthic and part of the
metaphyton, and are sometimes found in polluted waters. Others
grow in thermal and mineral springs or saline lakes and ponds.
Fifty species have been described based on filament morphology,
ultrastructure, and molecular sequencing. Both genetic and morphological
analyses have confirmed the separation of the genus Arthrospira
from Spirulina.
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| The dry biomass
of Spirulina is 50-70% protein - as much as in nuts, grains,
and soybeans. The cell walls are made of mucopolysaccarides,
which are more easily digested than the cellulose cell walls
of other microalgae. Spirulina also contains high amounts
of vitamin B, essential unsaturated fatty acids, and betacarotene.
Digested betacarotene is converted to vitamin A, which helps
to prevent xerothalmia, a disease causing blindness in malnourished
children. Spirulina is therefore valuable for commercial
cultivation and is grown in shallow raceways stirred by paddles
or in closed outdoor bioreactors that are carefully monitored
for contamination by toxic cyanobacteria. In Africa, Spirulina
has traditionally been harvested for use in sauces, with 9-13
grams on average consumed in each meal. |
