Microalgae Photosynthesis for Nutrient Recovery and Value Addition

The current chapter discusses the potential applications of microalgae in various fields, including human health, nutrition, and biofuel production. Microalgae are single-cell photosynthetic eukaryotes that can grow in both fresh and marine environments, and they are capable of producing high-value chemicals and fuels. The carbon fixation process results in the biosynthesis of photosynthates, which can be channeled into different primary and secondary metabolites depending on the growth conditions and nutrient load. Microalgae are known to accumulate intracellular lipids, including exotic lipid groups such as eicosapentaenoic acid and docosahexaenoic acid which have multiple health benefits. They can also produce other high-value products such as natural dyes, polysaccharides, pigments, antioxidants, bioactive compounds, and proteins. The use of microalgae as a renewable feedstock has the potential to provide multiple benefits, including sustainable energy production, wastewater treatment, and the production of high-value chemicals. Chlorophyll and its derivatives have therapeutic properties and exhibit chemopreventive effects, while carotenoids play a vital role in preventing oxidative damage to cells and tissues. Microalgae are abundant sources of carotenoids including β-carotene, astaxanthin, lutein, fucoxanthin, zeaxanthin, antheraxanthin, violaxanthin, neoxanthin, loroxanthin, diadinoxanthin, diatoxanthin, and siphonein. Astaxanthin is the most industrially exploited ketocarotenoid with a high market value and exhibits higher antioxidant activity than other antioxidants. The chapter also highlights various health benefits of carotenoids, including retinal and visual dysfunctions, immune modulation, anticancer properties, and inhibiting cardiovascular diseases.