Microalgae: Classification, bioactives, medicinal properties, industrial applications, and future prospectives

Microalgae are unicellular microorganism found in marine and freshwater water ecosystem in benthic and littoral habitats. It largely contributes for photosynthetic activities in aquatic system. They are known to produce enormous bioactive ingredients having applications in pharmaceutical, food, cosmetic, bioenergy industries, and phycoremediation technologies. Algal bioactives are in great demand to meet the nutritional needs and management of acute and chronic diseases of the growing population of world. They can be used as a functional food due to the presence of essential fatty acids such as eicosapentaenoic acid, docosahexanoic acid (DHA), and pigments like carotenoids (for example, fucoxanthin, β-carotene, lutein, and astaxanthin). Diverse bioactive metabolites from microalgae have studied for anticancer, antifungal, antibacterial, and immunosuppressive properties. Due to optimum level of pigments and fatty acid, microalgae have attracted cosmetic and biofuel industries, respectively. Several studies have successfully reported implementation of microalgae in the treatment of wastewater. Easy cultivation and maintenance of microalgae for the targeted production and extraction of bioactive compounds is the advantage over other bioresources. In the present chapter, we thoroughly discussed numerous bioactive compounds from microalgae with health benefits and their potential to ameliorate different diseases. Further, recent advances in use of microalgae for the remediation of environmental pollutant are discussed. Additionally, we have summarized present status and future prospects of bioactive compounds use in different industries.