Biology Reference
In-Depth Information
Heterokontophyta is the most diverse algal group with huge commercial
and biotechnological potentials. They range in size from microscopic
single cells to giant kelp averaging several meters. They form one of the
most diverse algal groups with huge commercial and biotechnological
potentials. Euglenophyta encompasses unicellular fl agellate organisms,
and comprise of 40 genera and 900 species. The chlorophast originating
from the green algae contains chlorophylls-a and -b and carotenoids such
as neoxanthin, diadinoxanthin and β-carotene. The phylum Haptophyta
is a group of unicellular fl agellates, having a brownish or yellowish-green
color due to chlorophylls-a and -c
1
/c
2
and carotenoids such as β-carotene,
fucoxanthin, and others. The cells are commonly covered with scales
made mainly of carbohydrates or calcium bicarbonate, and hence many
species produce calcifi ed scales. About 70 genera and 300 species have
been isolated to date, most being tropical marine species, forming food for
aquatic communities (Nybakken, 1997).
Blue Green Algae or Cyanobacteria
Blue green algae also referred as cyanobacteria, are oxygenic phytosynthetic
prokaryotes that show large diversity in their morphology, physiology,
ecology, biochemistry and other characteristics. Currently, more than
2000 species of cyanobacteria are recognized. These organisms are
distributed widely not only in salt water but also in freshwater, brackish
water, polar areas, and hot springs. In tropical and subtropical oceans,
the marine cyanobacterium,
Trichodesmium
, form tufts of fi laments that
constitute a signifi cant fraction of the biomass suspended in the waters.
The cyanobacteria of the genus
Prochlorococcu
s are the smallest (0.6 µm
dia) and most numerous of the photosynthetic marine organisms. It
has been estimated that a drop of seawater contains up to 20,000 cells
of the organisms belonging to
Prochlorococcus
. These and another marine
pelagic
Synechococcus
contribute largely to global oxygen production.
Cyanobacteria are generally considered to be associated with marine
plants and animals. Some of these organisms also exist in symbiotic
association with sponges, ascidians, echiuroid worms, planktonic
diatoms and dinofl agellates in order to survive in highly stressful marine
environments giving rise to several secondary metabolites, having
potentials as drugs and other bioactive compounds
(Matsunaga et al.,
2005; Falkowski, 2002).
Marine Microalgae as Food
Marine microalgae are hailed as the new “super food”, because they are
signifi cantly rich in nutrients. Ingestion of relatively small quantities of
microalgae can satisfy the requirements for some vitamins in animal and
