C. Storage polysaccharides (Renn 1997)
(1) Green algae
These polysaccharides are similar to the starch found in land plants and consist of
around 16–27% amylose, with amylopectin accounting for the remainder.
(2) Brown algae
The chief example is laminaran (b-glucan), which is hot water soluble. Content is as
high as 25% in Laminaria. Laminaran has been found to be synthesized from the
photosynthensis product mannitol. In Eisenia bicyclis, laminaran has a molecular
chain structure with b-D-glucopyanose connected by 1,3 and 1,6 linkages.
(3) Red algae
Known as red algae starch, these polysaccharides have been isolated from the
Gelidiopsis Furcedaria fastigiata and the Constantinea Constantinea sabutinea.
From their physical and chemical characteristics, they are believed to fall midway
between the higher plant starch amylopectin and the glycogen found in animals.
Pure red algae starch has been obtained through purification of Serraticardia
maxima, which flourishes in areas that are profuse with calcareous algae due to
seaweed withering on seaside rocks. Precursors for the red algae starch biosynthesis
mechanism are reported to include depolymerized compounds that have become the
subject of recent attention, including trehalose, floridoside, and isofloridoside.
6.8.3 Alginic Acid
Alginic acid is a polysaccharide contained in brown algae. The substance was
named alginic acid after alga, from the Latin for “seaweed.” Alginic acid was
discovered by the Scottish scientist Stanford in 1884 while examining the chemical
constituents of the brown alga Ascophyllum. After pre-treatment of brown algae
with dilute hydrochloric acid, acidification through the addition of hydrochloric
acid to a viscous solution extracted from an aqueous solution of alkaline chemicals
such as sodium carbonate or sodium hydroxide results in the formation of white,
fibrous precipitate, which can be dried to obtain alkali salts of alginic acid. Alginic
acid is white and odorless and exhibits acidity due to a separated carboxyl
group. The name alginic acid is used to refer to sodium alginate, which has an
especially broad range of uses.
Alginic acid is present in all brown algae, albeit in different quantities. For an
algae to serve as an alginic acid source for industrial purposes, it must meet several
conditions: large volumes, mass colony formation, growth in environments where
harvesting is easily performed, and not detracting from its functioning as a seaweed
forest.
172
6 Seaweed Biotechnology
(1) Green algae
These polysaccharides are similar to the starch found in land plants and consist of
around 16–27% amylose, with amylopectin accounting for the remainder.
(2) Brown algae
The chief example is laminaran (b-glucan), which is hot water soluble. Content is as
high as 25% in Laminaria. Laminaran has been found to be synthesized from the
photosynthensis product mannitol. In Eisenia bicyclis, laminaran has a molecular
chain structure with b-D-glucopyanose connected by 1,3 and 1,6 linkages.
(3) Red algae
Known as red algae starch, these polysaccharides have been isolated from the
Gelidiopsis Furcedaria fastigiata and the Constantinea Constantinea sabutinea.
From their physical and chemical characteristics, they are believed to fall midway
between the higher plant starch amylopectin and the glycogen found in animals.
Pure red algae starch has been obtained through purification of Serraticardia
maxima, which flourishes in areas that are profuse with calcareous algae due to
seaweed withering on seaside rocks. Precursors for the red algae starch biosynthesis
mechanism are reported to include depolymerized compounds that have become the
subject of recent attention, including trehalose, floridoside, and isofloridoside.
6.8.3 Alginic Acid
Alginic acid is a polysaccharide contained in brown algae. The substance was
named alginic acid after alga, from the Latin for “seaweed.” Alginic acid was
discovered by the Scottish scientist Stanford in 1884 while examining the chemical
constituents of the brown alga Ascophyllum. After pre-treatment of brown algae
with dilute hydrochloric acid, acidification through the addition of hydrochloric
acid to a viscous solution extracted from an aqueous solution of alkaline chemicals
such as sodium carbonate or sodium hydroxide results in the formation of white,
fibrous precipitate, which can be dried to obtain alkali salts of alginic acid. Alginic
acid is white and odorless and exhibits acidity due to a separated carboxyl
group. The name alginic acid is used to refer to sodium alginate, which has an
especially broad range of uses.
Alginic acid is present in all brown algae, albeit in different quantities. For an
algae to serve as an alginic acid source for industrial purposes, it must meet several
conditions: large volumes, mass colony formation, growth in environments where
harvesting is easily performed, and not detracting from its functioning as a seaweed
forest.
172
6 Seaweed Biotechnology