9.2 Occurrence in Nature
191
Turgeon 2015). The brown algae species of Laminaria and Saccharina are the more
abundant and more common sources of Laminaria; nonetheless, laminarin is also
found in other brown algae such as Fucus, Undaria and Ascophyllum species. These
species also serve as sources for other algae polysaccharides such as alginates and
fucoidan. Laminaria varies in the chain length and level of branching depending on
different species and growth factors. These chemical structure variations also have
an effect on solubility (Kadam et al. 2015) and bioactivity (Liu et al. 2018) of the
specific laminarin.
Laminarin production is thought to be part of the brown algae coping strategy to
survive the winter season. It is produced at the end of the peak growth rate in spring,
such that laminarin serves as a storage reserve source of carbon during the winter
season (Misurcova et al. 2012). Water-soluble carbohydrates are a more accessible
source of energy storage compared to insoluble carbon sources such as cellulose
(Hildebrand et al. 2017). Laminarin is therefore one of the soluble polysaccharides
the brown algae uses as a source of carbon.
9.3 Chemistry of Laminarin
Laminarin is built up of β,1-3 linked glucan with a low level of branching at the 1-6
linkages. Some β,1-6 intrachain linkages may also be present (Kadam et al. 2015).
Laminarin has a similar structure to Lichenan found in moss and lentinan found in
mushrooms but differs in the degree of branching and nature of glycosidic linkages
(Ojima et al. 2018).
9.3.1 Repeating Units
Laminarin is composed of mostly neutral sugars with small amounts of uronic acid
(Misurcova et al. 2012). The composition of the sugars varies for different species. For
example, while Saccharina longicruris contains up to 99% neutral sugars which is the
highest composition of neutral sugars thus far observed in laminarins, Ascophyllum
nodosum has 89.6% neutral sugars and Fucus vesiculosus contains 84.1% neutral
sugars. Nonetheless, the neutral sugars are always significantly more abundant in
laminarin. The arrangements and conformation of the repeating units also vary for
different species. Figure 9.1 compares the structure of laminarin extracted from E.
bicyclis with that from L. digitata (Liu et al. 2018).
To understand the difference between the laminarin from the two different species
of brown algae, the laminarin forms the two sources that were hydrolyzed using
microorganism Coprinopsis cinerea which metabolizes the enzyme endo-β-1,3glucanase which breaks the β-1,3 glycosidic bond in laminarin. By analyzing the
residues from the hydrolysis of the different laminarin using high-performance anion
exchange, chromatography combined with mass spectrometry revealed the building
191
Turgeon 2015). The brown algae species of Laminaria and Saccharina are the more
abundant and more common sources of Laminaria; nonetheless, laminarin is also
found in other brown algae such as Fucus, Undaria and Ascophyllum species. These
species also serve as sources for other algae polysaccharides such as alginates and
fucoidan. Laminaria varies in the chain length and level of branching depending on
different species and growth factors. These chemical structure variations also have
an effect on solubility (Kadam et al. 2015) and bioactivity (Liu et al. 2018) of the
specific laminarin.
Laminarin production is thought to be part of the brown algae coping strategy to
survive the winter season. It is produced at the end of the peak growth rate in spring,
such that laminarin serves as a storage reserve source of carbon during the winter
season (Misurcova et al. 2012). Water-soluble carbohydrates are a more accessible
source of energy storage compared to insoluble carbon sources such as cellulose
(Hildebrand et al. 2017). Laminarin is therefore one of the soluble polysaccharides
the brown algae uses as a source of carbon.
9.3 Chemistry of Laminarin
Laminarin is built up of β,1-3 linked glucan with a low level of branching at the 1-6
linkages. Some β,1-6 intrachain linkages may also be present (Kadam et al. 2015).
Laminarin has a similar structure to Lichenan found in moss and lentinan found in
mushrooms but differs in the degree of branching and nature of glycosidic linkages
(Ojima et al. 2018).
9.3.1 Repeating Units
Laminarin is composed of mostly neutral sugars with small amounts of uronic acid
(Misurcova et al. 2012). The composition of the sugars varies for different species. For
example, while Saccharina longicruris contains up to 99% neutral sugars which is the
highest composition of neutral sugars thus far observed in laminarins, Ascophyllum
nodosum has 89.6% neutral sugars and Fucus vesiculosus contains 84.1% neutral
sugars. Nonetheless, the neutral sugars are always significantly more abundant in
laminarin. The arrangements and conformation of the repeating units also vary for
different species. Figure 9.1 compares the structure of laminarin extracted from E.
bicyclis with that from L. digitata (Liu et al. 2018).
To understand the difference between the laminarin from the two different species
of brown algae, the laminarin forms the two sources that were hydrolyzed using
microorganism Coprinopsis cinerea which metabolizes the enzyme endo-β-1,3glucanase which breaks the β-1,3 glycosidic bond in laminarin. By analyzing the
residues from the hydrolysis of the different laminarin using high-performance anion
exchange, chromatography combined with mass spectrometry revealed the building