Algae-Mediated Carbon Dioxide Sequestration for Climate Change Mitigation and Conversion to Value-Added Products - Biotechnological Applications of Microalgae - page 171

foods (Humphrey, 2004). Microalgae that have already been grown in large volumes
(e.g., Chlorella and Spirulina ) could be explored for the commercial production of
chlorophylls for food application.
Microalgae might also be a potential source for the commercial production of
lutein. Lutein usually occurs in microalgae in its free nonesterified form. Microalga
Muriellopsis sp. has been shown to accumulate higher contents of lutein with high
productivities of biomass under photo-autotrophic conditions (Del Campo et al.,
2000). Studies on the cultivation of Muriellopsis in closed photobioreactors as well
as open-pond systems have been carried out (Del Campo et al., 2001, 2007; Blanco
et al., 2007). The free lutein content of Muriellopsis biomass was found to be in the
range of 0.4% to 0.6% on a dry weight basis (Del Campo et al., 2007). Scenedesmus
sp. and Chlorella sp. have also been reported to accumulate lutein (Del Campo et al.,
2000, 2004; 2007; Shi et al., 2006).
The red microalga Porphyridium has been shown to be a potential source of
sulfated polysaccharides that form thermally reversible gels similar to macroalgae-
derived polysaccharides, agar, and carrageenan. These gels have various commercial
applications, including in foods, as gelling agents, thickeners, stabilizers, and emul-
sifiers (Raja et al., 2008). As a microalga, Porphyridium may offer an advantage over
macroalgae due to its relatively faster growth rate. Small-scale outdoor cultivation
studies with Porphyridium have been carried out (Arad et al., 1985).
The chlorophyll, lutein, and polysaccharides from microalgae could be commer-
cially important VAPs for food applications. However, processes for their commer-
cial production from microalgae have not yet been developed and require further
R&D studies as well as the development of markets for these products. Table 11.4
provides a list of some of the microalgal species with relevance for biotechnologi-
cal applications in food. From Table 11.4, it is very clear that some progress has
been made, and there are commercial microalgae applications, including pigments,
fatty acids, and health foods. However, studies on the characterization of indigenous
microalgae from natural habitats as potential sources of food, feed, and VAPs have
remained relatively limited, and there is the need to tap into the vast biodiversity of
microalgae growing in natural habitats under diverse climatic conditions for finding
suitable candidate microalgae for various applications.
11.5 FUTURE NEEDS
Research efforts into using microalgae for CO 2 sequestration, biodiesel produc-
tion, and other VAP syntheses will continue to power several of the assets inherent
in these photosynthetic organisms. The high lipid content of microalgae has been
taken as the major screening criteria for selecting and exploiting such species for
biodiesel production, but has not been evaluated critically. The species that have
been exploited for biodiesel production are very few (Griffiths and Harrison, 2009).
The majority of the research work has focused on increasing lipid content and bio-
mass productivity, whereas the studies related to chemical conversion of lipid to
biodiesel, quality improvement, and cost reduction of the process are progressing at
a slow pace (Krohn et al., 2011). Taking into consideration the current scenario, there
is a need to look into the complete fatty acid profile of microalgal lipids in addition