Introduction - Biotechnological Applications of Microalgae - page 2

products such as polyunsaturated fatty acid (PUFA) oils (e.g., γ-linolenic acid
(GLA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic
acid (DHA)) (Spolaore et al., 2006). In addition, microalgae such as Dunaliella
and Haematococcus are important sources of carotenoids such as β-carotene and
astaxanthin, respectively (Spolaore et al., 2006). Furthermore, the cyanobacterium
Anthrospira and the rhodophyte Porphyridium are the main commercial producers
of phycobiliproteins (i.e., phycoerythrin and phycocyanin), which are used as natu-
ral dyes and for pharmaceutical applications (Spolaore et al., 2006). Potential bio-
technological applications and value-added products generated from microalgae are
discussed in Chapter 10 of this volume.
Chlorella , Arthrospira, and Nostoc are cultivated worldwide for human and
animal nutrition, owing to their chemical composition (Spolaore et al., 2006).
Microalgae have been hailed as the panacea for the dwindling petroleum-based
fuels, and the preponderance of shorter-chain fatty acids has significance for their
potential as diesel fuels (Chisti, 2007; Williams and Laurens, 2010). The efficacy
of using microalgal biomass and lipids as alternative biofuels is currently a topical
issue. Biofuels such as biodiesel, biomethane, biohydrogen, biobutanol , etc., can be
generated from microalgae (Chisti, 2007). Current research is targeting other novel
potential biotechnological applications in aquaculture, cosmetics, pharmaceuticals,
and animal and human nutrition. It is envisaged that future research should focus on
microalgal strain improvement through genetic engineering, in order to diversify and
economically improve product competitiveness (Spolaore et al., 2006). Microalgal
genetic manipulation is still in its infancy and is a pertinent area of investigation in
order to improve the quality and quantity of products generated from microalgae.
However, the development of nondestructive product recovery techniques from con-
tinuous cultivation systems will greatly improve product yield.
Successful microalgal cultivation and generation of these products calls for metic-
ulous and rigorous microalgal strain selection. Two important steps in obtaining a
robust and suitable microalgal candidate are (1) bioprospecting of target microalgal
strain samples from diverse habitats, and (2) strain selection, isolation, and purifica-
tion using conventional and advanced microbiological methods (Grobbelaar, 2009;
Mutanda et al ., 2011). Suitable microalgal strains can be obtained commercially
from registered authentic culture collection centers. The microalgal strain of choice
is maintained under laboratory conditions, either as a freeze-dried sample or as a
slant on solid media at 4°C with routine subculturing. The ever-growing field of phy-
cology has introduced new, exciting, and efficient techniques for maintaining micro-
algal cultures at ultra-low temperatures (i.e., cryopreservation). Microalgal strain
selection for biodiesel production is discussed in detail in Chapter 3 of this volume.
The enumeration of microalgae poses a real challenge due to the requirement of
sophisticated equipment such as flow cytometers. The use of optical microscopes
for cell counting is relatively cheaper, although not very accurate as compared to
faster automated cell counting techniques (Guillard and Sieracki, 2005; Marie et al.,
2005). Microalgal cells are counted in order to estimate the size of the cultured pop-
ulation and to estimate the rate of culture growth (i.e., determination of the rate of