Bioactive Polysaccharides from Microalgae: A Close Look at the Biomedical Applications.

There is a current tendency towards bioactive natural products that can be used in different areas such as food, pharmaceutical, and biomedical. In the last decades, polysaccharides have attracted increasing interest because of their potent nontoxic effects, therapeutic properties, and diversified range of applications. Polysaccharides are complex and heterogeneous macromolecules constituted of different monosaccharides and, in some cases, of glucuronic acid and sulphate groups. Polysaccharides with biological activity can be derived from plants, animals and microorganisms, especially microalgae. Microalgae are considered one of the most promising sources of these compounds that have already proved to have several important biological properties. In this sense, our objective is to elucidate the use of bioactive polysaccharides from microalgae in biomedical applications, emphasizing the biological activity of these compounds. Furthermore, the microalgal biomass production systems and polysaccharides extraction methods were presented and discussed.

Microalgae-derived polysaccharides: Potential building blocks for biomedical applications.

In recent years, the increasing concern about human health well-being has strongly boosted the search for natural alternatives that can be used in different fields, especially in biomedicine. This has put microalgae-based products in evidence since they contain many bioactive compounds, of which polysaccharides are attractive due to the diverse physicochemical properties and new or improved biological roles they play. Polysaccharides from microalgae, specially exopolysaccharides, are critically important for market purposes because they can be used as anti-inflammatory, immunomodulatory, anti-glycemic, antitumor, antioxidant, anticoagulant, antilipidemic, antiviral, antibacterial, and antifungal agents. Therefore, to obtain higher productivity and competitiveness of these naturally available compounds, the cultivation parameters and the extraction/purification processes must be better optimized in order to bring perspectives for the exploitation of products in commercial and clinical practice. In this sense, the objective of the present review is to elucidate the potential biomedical applications of microalgae-derived polysaccharides. A closer look is taken at the main polysaccharides produced by microalgae, methods of extraction, purification and structural determination, biological activities and their applications, and current status.

Carbon dioxide capture and use in photobioreactors: The role of the carbon dioxide loads in the carbon footprint.

This research evaluated the carbon dioxide capture and use by Scenedesmus obliquus in a photobioreactor under different CO2 loads. Performance indicators, carbon and energy balances, sustainability indicators, and carbon credits on the photobioreactor were assessed. The results expressed that the CO2 loads of 384.9 kg/m3/d (15% CO2) provide the best trade-off for the process. For this condition, maximum biomass productivities of 0.36 kg/m3/d, carbon dioxide conversion rates of 0.44 kgCO2/m3/d, and oxygen release rates of 0.33 kgO2/m3/d were observed, reaching maximum CO2 removal efficiencies of 30.76%. Volatile organic compounds were the major products generated (>80%). However, only <3% was fixed in biomass. From the environmental and economic point of view, the net energy ratio was 3.44, while the potential carbon credit was of 0.04 USD per m3 of culture. Finally, the use of adequate CO2 loads was also proven to be determinant to improve the global performance of the system.