252 Marine Macro- and Microalgae: An Overview
higher growth rates, microalgae do not require arable land and can be grown all year round (Borowitzka
1999) without the use of polluting, potentially toxic chemicals such as herbicides or pesticides (Rodolfi
et al. 2008). They can produce lipids, carbohydrates, and proteins in large amounts over short periods
of time that can be further processed into both biofuels and useful chemicals (Gangadhar et al. 2016a;
Pereira et al. 2016). Moreover, some microalgal species can be grown in the absence of fresh water
and perform very well in brackish or salt water (Christenson and Sims 2011). It is estimated that the
biomass productivity of microalgae could be 50 times higher than that of switchgrass (i.e., Miscanthus),
which is the fastest growing terrestrial plant (Demirbas 2006; Nakamura 2006). The exponential growth
rates can double their biomass in periods as short as 3.5 h (Metting 1996; Spolaore et al. 2006; Chisti
2007). Secondly, in spite of their growth in aqueous media, algae need less freshwater than vegetable
oil crops (Dismukes et al. 2008). Furthermore, as microalgae can be cultivated in brackish water on
non-arable land, associated environmental impacts of land use are minimised (Searchinger et al. 2008),
without compromising the production of food, fodder, and other products derived from terrestrial crops
(Chisti 2007). The dual application of microalgae for phycoremediation of organic effluents from the
agrochemical industry (Cantrell et al. 2008) turns microalgal cultivation into an eco-friendly process with
no secondary pollution, allowing also an efficient recycling of nutrients (e.g., nitrogen and phosphorus)
present in industrial and/or municipal wastewaters (Munoz and Guieysse 2006; Pizarro et al. 2006;
Mulbry et al. 2008; Giorgos and Dimitris 2011; Rawat et al. 2011; Schulze et al. 2017a). Other studies
have reported that lipid content in some microalgae increases under different cultivation conditions such
as nitrogen deprivation (Iillman et al. 2000; Hsieh and Wu 2009), high light intensity (Khotimchenko
and Yakovleva 2005), and high salt (Araujo et al. 2011). Moreover, phosphorus depletion found to be
more efficient inducer of TAG as compared to that of nitrate depletion (Wu et al. 2015; Schüler et al.
2017 and references therein). Taken together, the use of microalgae is thus highly desirable since they
are able to serve a dual role of bioremediation of wastewater as well as generating biomass for biofuel
production with resultant carbon dioxide sequestration, even if temporary (Olguın 2003; Mulbry et al.
2008; Jasvinder and Gu 2010; Mata et al. 2010; Amaro et al. 2011).
Nutraceutical applications of microalgae
Biofuels from microalgae biomass cannot be commercially feasible unless value-added products are
optimally utilized. Microalgae are a potential source of various applications such as nutraceutical (i.e.,
polyunsaturated fatty acids, PUFA), vitamins (Schmid 2009; Pereira et al. 2012), anti-oxidants, and metal
chelators (Custódio et al. 2012; Gangadhar et al. 2016b) as well as bioactive value-added products as
healthy ingredients for functional food (Matos et al. 2017). PUFA such as eicosapentaenoic (EPA) and
docosahexaenoic (DHA) acids are n-3 fatty acids (Pereira et al. 2012), which are generally obtained from
fish oil for human consumption (Luiten et al. 2003), providing a high-value food supplement (Harun et
al. 2010a). Contrary to fish and mammals, microalgae produce their own n-3 fatty acids (Belarbi et al.
2000). EPA and DHA have their individual medical applications, including treatment of cardiovascular
disease, migraine headache, and psoriasis (Singh et al. 2005); prevention and cure of cancer, AIDS,
and hypercholesterolemia; as well as stimulation of the immune system, and body detoxification (Patil
et al. 2007). Chlorophyll is another pharmaceutically important compound and it has been reported as
source of a natural ingredient in processed food (Humphrey 2004) and cosmetics industries (Erica 1996)
and as a chelating agent in ointment. It has also been used in pharmaceutical applications, especially
liver recovery and ulcer treatment; it appears to repair cells, increase haemoglobin levels in blood,
and cell growth (Puotinen 1999). Moreover, the cyanobacterium Arthrospira sp. is being used in food
supplements due to its excellent nutrient composition and digestibility (Kumar et al. 2005), being a rich
source of vitamins, particularly vitamin B 12 and β-carotene and minerals (Thajuddin and Subramanian
2005). Chlorella sp. has been reported as potential food, principally because it contains most nutrients
required for human nourishment (Spolaore et al. 2006). In addition to green algae, red algae, mainly
Porphyra, and brown microalgae were deemed as safe for human consumption as food (Besada et al.
2009). Microalgae also play a key role in high-grade animal nutrition food (Dhargalkar and Verlecar
2009), due to their low caloric content, high concentration of minerals, vitamins and proteins, as well as a
higher growth rates, microalgae do not require arable land and can be grown all year round (Borowitzka
1999) without the use of polluting, potentially toxic chemicals such as herbicides or pesticides (Rodolfi
et al. 2008). They can produce lipids, carbohydrates, and proteins in large amounts over short periods
of time that can be further processed into both biofuels and useful chemicals (Gangadhar et al. 2016a;
Pereira et al. 2016). Moreover, some microalgal species can be grown in the absence of fresh water
and perform very well in brackish or salt water (Christenson and Sims 2011). It is estimated that the
biomass productivity of microalgae could be 50 times higher than that of switchgrass (i.e., Miscanthus),
which is the fastest growing terrestrial plant (Demirbas 2006; Nakamura 2006). The exponential growth
rates can double their biomass in periods as short as 3.5 h (Metting 1996; Spolaore et al. 2006; Chisti
2007). Secondly, in spite of their growth in aqueous media, algae need less freshwater than vegetable
oil crops (Dismukes et al. 2008). Furthermore, as microalgae can be cultivated in brackish water on
non-arable land, associated environmental impacts of land use are minimised (Searchinger et al. 2008),
without compromising the production of food, fodder, and other products derived from terrestrial crops
(Chisti 2007). The dual application of microalgae for phycoremediation of organic effluents from the
agrochemical industry (Cantrell et al. 2008) turns microalgal cultivation into an eco-friendly process with
no secondary pollution, allowing also an efficient recycling of nutrients (e.g., nitrogen and phosphorus)
present in industrial and/or municipal wastewaters (Munoz and Guieysse 2006; Pizarro et al. 2006;
Mulbry et al. 2008; Giorgos and Dimitris 2011; Rawat et al. 2011; Schulze et al. 2017a). Other studies
have reported that lipid content in some microalgae increases under different cultivation conditions such
as nitrogen deprivation (Iillman et al. 2000; Hsieh and Wu 2009), high light intensity (Khotimchenko
and Yakovleva 2005), and high salt (Araujo et al. 2011). Moreover, phosphorus depletion found to be
more efficient inducer of TAG as compared to that of nitrate depletion (Wu et al. 2015; Schüler et al.
2017 and references therein). Taken together, the use of microalgae is thus highly desirable since they
are able to serve a dual role of bioremediation of wastewater as well as generating biomass for biofuel
production with resultant carbon dioxide sequestration, even if temporary (Olguın 2003; Mulbry et al.
2008; Jasvinder and Gu 2010; Mata et al. 2010; Amaro et al. 2011).
Nutraceutical applications of microalgae
Biofuels from microalgae biomass cannot be commercially feasible unless value-added products are
optimally utilized. Microalgae are a potential source of various applications such as nutraceutical (i.e.,
polyunsaturated fatty acids, PUFA), vitamins (Schmid 2009; Pereira et al. 2012), anti-oxidants, and metal
chelators (Custódio et al. 2012; Gangadhar et al. 2016b) as well as bioactive value-added products as
healthy ingredients for functional food (Matos et al. 2017). PUFA such as eicosapentaenoic (EPA) and
docosahexaenoic (DHA) acids are n-3 fatty acids (Pereira et al. 2012), which are generally obtained from
fish oil for human consumption (Luiten et al. 2003), providing a high-value food supplement (Harun et
al. 2010a). Contrary to fish and mammals, microalgae produce their own n-3 fatty acids (Belarbi et al.
2000). EPA and DHA have their individual medical applications, including treatment of cardiovascular
disease, migraine headache, and psoriasis (Singh et al. 2005); prevention and cure of cancer, AIDS,
and hypercholesterolemia; as well as stimulation of the immune system, and body detoxification (Patil
et al. 2007). Chlorophyll is another pharmaceutically important compound and it has been reported as
source of a natural ingredient in processed food (Humphrey 2004) and cosmetics industries (Erica 1996)
and as a chelating agent in ointment. It has also been used in pharmaceutical applications, especially
liver recovery and ulcer treatment; it appears to repair cells, increase haemoglobin levels in blood,
and cell growth (Puotinen 1999). Moreover, the cyanobacterium Arthrospira sp. is being used in food
supplements due to its excellent nutrient composition and digestibility (Kumar et al. 2005), being a rich
source of vitamins, particularly vitamin B 12 and β-carotene and minerals (Thajuddin and Subramanian
2005). Chlorella sp. has been reported as potential food, principally because it contains most nutrients
required for human nourishment (Spolaore et al. 2006). In addition to green algae, red algae, mainly
Porphyra, and brown microalgae were deemed as safe for human consumption as food (Besada et al.
2009). Microalgae also play a key role in high-grade animal nutrition food (Dhargalkar and Verlecar
2009), due to their low caloric content, high concentration of minerals, vitamins and proteins, as well as a