3
Microalgal Metabolism and
their Utilisation
Michael A. Borowitzka
Introduction
The diverse metabolic pathways and the variety of expression of these underlie the interest in microalgae
as sources of potentially valuable chemicals and products, and the use of microalgae for a range of
processes such as waterwater treatment, soil bioremediation and as animal feed. Microalgae, defined as
those unicellular, colonial, and filamentous species of eukaryotes and the prokaryotic cyanobacteria (bluegreen algae) can be found in most algal phyla. Microalgae are already important commercial sources
of high-value chemicals including β-carotene, astaxanthin (Borowitzka 2010), phycocyanin (Eriksen
2008), and long-chain polyunsaturated fatty acids such as eicosapentaenoic acid, docosahexaenoic acid,
and arachidonic acid (Ratledge 2010; Wynn et al. 2010), as well as being used as human nutritional
supplements (Belay 1997; Iwamoto 2004) and for animal nutrition in aquaculture (Borowitzka 1997;
Neori 2011). Microalgae are continuing to be developed as potential sources of a range of other chemicals
and products (Borowitzka 2013a), and are receiving intense attention as potential sources of renewable
fuels (Wijffels and Barba 2010; Borowitzka and Moheimani 2013; Unkefer et al. 2017).
Irrespective of the application of the microalgae and of the culture system which may be used,
successful culture and product formation requires a good understanding of algal biology, physiology, and
biochemistry. An understanding of those factors which affect effective utilization of light, photosynthesis,
respiration, nutrient uptake and utilization, and the regulation of metabolism in microalgae assists in
the selection of the most suitable strains (Borowitzka 2013b), the design of culture systems, and the
optimisation of culture conditions to produce the desired product (Borowitzka 2016).
Photosynthesis
The particular attraction of microalgae for practical and commercial applications is that they can use
light energy to fix inorganic carbon in photosynthesis ultimately to produce a wide variety of organic
molecules. There are also species which can take up organic carbon molecules in the light as sources
Algae R&D Centre, Murdoch University, Murdoch, Western Australia 6150, Australia.
Email: m.borowitzka@murdoch.edu.au
Microalgal Metabolism and
their Utilisation
Michael A. Borowitzka
Introduction
The diverse metabolic pathways and the variety of expression of these underlie the interest in microalgae
as sources of potentially valuable chemicals and products, and the use of microalgae for a range of
processes such as waterwater treatment, soil bioremediation and as animal feed. Microalgae, defined as
those unicellular, colonial, and filamentous species of eukaryotes and the prokaryotic cyanobacteria (bluegreen algae) can be found in most algal phyla. Microalgae are already important commercial sources
of high-value chemicals including β-carotene, astaxanthin (Borowitzka 2010), phycocyanin (Eriksen
2008), and long-chain polyunsaturated fatty acids such as eicosapentaenoic acid, docosahexaenoic acid,
and arachidonic acid (Ratledge 2010; Wynn et al. 2010), as well as being used as human nutritional
supplements (Belay 1997; Iwamoto 2004) and for animal nutrition in aquaculture (Borowitzka 1997;
Neori 2011). Microalgae are continuing to be developed as potential sources of a range of other chemicals
and products (Borowitzka 2013a), and are receiving intense attention as potential sources of renewable
fuels (Wijffels and Barba 2010; Borowitzka and Moheimani 2013; Unkefer et al. 2017).
Irrespective of the application of the microalgae and of the culture system which may be used,
successful culture and product formation requires a good understanding of algal biology, physiology, and
biochemistry. An understanding of those factors which affect effective utilization of light, photosynthesis,
respiration, nutrient uptake and utilization, and the regulation of metabolism in microalgae assists in
the selection of the most suitable strains (Borowitzka 2013b), the design of culture systems, and the
optimisation of culture conditions to produce the desired product (Borowitzka 2016).
Photosynthesis
The particular attraction of microalgae for practical and commercial applications is that they can use
light energy to fix inorganic carbon in photosynthesis ultimately to produce a wide variety of organic
molecules. There are also species which can take up organic carbon molecules in the light as sources
Algae R&D Centre, Murdoch University, Murdoch, Western Australia 6150, Australia.
Email: m.borowitzka@murdoch.edu.au