5 Microalgae Production in Fresh Market Wastewater …
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Microalgae is also known as an essential food source for all stages of marine bivalve
mollusc, larval stages of marine gastropods and larvae of several fish species due to
the large amounts of useful carbohydrates, proteins and antioxidants (Muller-feuga
2000; Al-Gheethi et al. 2019). Moreover, microalgae contain a great essential of
polyunsaturated fatty acids such as omega-3 and omega-6. Good pigments, minerals
and vitamins content in microalgae are also the beneficial characteristics that could
make this microscopic plant the best alternative for protein replacement in fish feed
(Maizatul et al. 2017).
5.4 Physicochemical Properties of Microalgae
Microalgae could store high concentration of carbohydrates because it shows a relatively high photo conversion efficiency which are more than 50% of dry weight
(Ho et al. 2012; Jais et al. 2017), relevant biological functions in microalgae cells as
a storage, protection and structural molecules (Arad and Levy-Ontman 2010). The
composition of carbohydrates depends on the species. For examples, cyanobacteria
synthesize glycogen (A − 1, 4 linked glucan), red algae floridean synthesize starch
(hybrid of starch and glycogen) and green algae synthesize amylopectin-like polysaccharides (starch) (Markou and Georgakakis 2011). Several species of microalgae
such as Porphyridium cruentum (40–57%) and Spirogyra sp. (33–64%) have a naturally higher content of carbohydrate (Harun et al. 2010). The carbohydrate content
of microalgae can be modified by cultivation and environmental factors, salt stress,
light intensity and temperature. Moreover, the type of carbon source and metabolism
process is also one of the major factors that influence sugar content (Harun et al.
2010; Pahazri et al. 2016).
In 1950s some species of microalgae were introduced as a source of protein
(Soletto et al. 2005). Protein content in microalgae is in the form of amino acids
which cannot be synthesized in human or animal bodies. A study by Becker (2007)
reported that microalgae are good quality of non-conventional protein sources thus
suitable to be used as protein alternatives in fishmeal.
Three species that are commonly used for protein production are Chlorella (55%
protein content), Spirulina (Arthrospira) (65% of protein) and Dunaliella (57% of
protein content) (Gonzalez-Benito et al. 2009). Spirulina has received more attention
due to its good quality and quantity of protein reaches 70% of dry weight. According
to Andrade et al. (2018). Spirulina proteins that are rich in essential amino acids has
been used for a long time as protein supplement and also to manufacture healthy
foods. This finding is supported by Becker (2007), who stated that amino acids
(i.e., lysine, methionine, tryptophan, threonine, valine, histidine and isoleucine) in
microalgae are comparable with the conventional protein sources such as egg and
soybean (Table 5.2).
In addition to high and good quality of carbohydrates and protein content, microalgae have also been reported to contain high antioxidants. Astaxanthin, β-Carotene
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Microalgae is also known as an essential food source for all stages of marine bivalve
mollusc, larval stages of marine gastropods and larvae of several fish species due to
the large amounts of useful carbohydrates, proteins and antioxidants (Muller-feuga
2000; Al-Gheethi et al. 2019). Moreover, microalgae contain a great essential of
polyunsaturated fatty acids such as omega-3 and omega-6. Good pigments, minerals
and vitamins content in microalgae are also the beneficial characteristics that could
make this microscopic plant the best alternative for protein replacement in fish feed
(Maizatul et al. 2017).
5.4 Physicochemical Properties of Microalgae
Microalgae could store high concentration of carbohydrates because it shows a relatively high photo conversion efficiency which are more than 50% of dry weight
(Ho et al. 2012; Jais et al. 2017), relevant biological functions in microalgae cells as
a storage, protection and structural molecules (Arad and Levy-Ontman 2010). The
composition of carbohydrates depends on the species. For examples, cyanobacteria
synthesize glycogen (A − 1, 4 linked glucan), red algae floridean synthesize starch
(hybrid of starch and glycogen) and green algae synthesize amylopectin-like polysaccharides (starch) (Markou and Georgakakis 2011). Several species of microalgae
such as Porphyridium cruentum (40–57%) and Spirogyra sp. (33–64%) have a naturally higher content of carbohydrate (Harun et al. 2010). The carbohydrate content
of microalgae can be modified by cultivation and environmental factors, salt stress,
light intensity and temperature. Moreover, the type of carbon source and metabolism
process is also one of the major factors that influence sugar content (Harun et al.
2010; Pahazri et al. 2016).
In 1950s some species of microalgae were introduced as a source of protein
(Soletto et al. 2005). Protein content in microalgae is in the form of amino acids
which cannot be synthesized in human or animal bodies. A study by Becker (2007)
reported that microalgae are good quality of non-conventional protein sources thus
suitable to be used as protein alternatives in fishmeal.
Three species that are commonly used for protein production are Chlorella (55%
protein content), Spirulina (Arthrospira) (65% of protein) and Dunaliella (57% of
protein content) (Gonzalez-Benito et al. 2009). Spirulina has received more attention
due to its good quality and quantity of protein reaches 70% of dry weight. According
to Andrade et al. (2018). Spirulina proteins that are rich in essential amino acids has
been used for a long time as protein supplement and also to manufacture healthy
foods. This finding is supported by Becker (2007), who stated that amino acids
(i.e., lysine, methionine, tryptophan, threonine, valine, histidine and isoleucine) in
microalgae are comparable with the conventional protein sources such as egg and
soybean (Table 5.2).
In addition to high and good quality of carbohydrates and protein content, microalgae have also been reported to contain high antioxidants. Astaxanthin, β-Carotene