Microalgae Polysaccharides: An Overview of Production, Characterization, and Potential Applications

Abstract

Microalgae and cyanobacteria are photosynthetic microorganisms capable of synthesizing several biocompounds, including polysaccharides with antioxidant, antibacterial, and antiviral properties. At the same time that the accumulation of biomolecules occurs, microalgae can use wastewater and gaseous effluents for their growth, mitigating these pollutants. The increase in the production of polysaccharides by microalgae can be achieved mainly through nutritional limitations, stressful conditions, and/or adverse conditions. These compounds are of commercial interest due to their biological and rheological properties, which allow their application in various sectors, such as pharmaceuticals and foods. Thus, to increase the productivity and competitiveness of microalgal polysaccharides with commercial hydrocolloids, the cultivation parameters and extraction/purification processes have been optimized. In this context, this review addresses an overview of the production, characterization, and potential applications of polysaccharides obtained by microalgae and cyanobacteria. Moreover, the main opportunities and challenges in relation to obtaining these compounds are highlighted.

Preliminary Characterization of a Spray-Dried Hydrocolloid from a High Andean Algae (Nostoc sphaericum)

“…Hydrocolloids are highly hydrophilic substances of high molecular weight, with good water solubility and hydration [ 1 , 2 ], are mainly of biological origins, such as algae, seeds, and tubers, and are made up of polysaccharides including gum arabic, guar gum, carboxymethylcellulose, carrageenan, starch, pectins, and gelatins [ 3 , 4 ], which present different capacity to form gels or act as thickeners in different conditions and at low concentrations, forming colloids with particular structures; due to this property they are widely used in the food industry as additives [ 5 , 6 ].…”

“…The current trend in food processing is the use of natural additives as thickeners and stabilizers, with adequate nutritional and techno-functional properties, focusing research on sources of vegetable origin [ 5 , 6 , 7 , 8 , 9 ]; hydrocolloids have recently been extracted from algae, one of them being the Nostocaceae family [ 3 , 10 , 11 , 12 ].…”

Recent Advances of Microalgae Exopolysaccharides for Application as Bioflocculants

“…EPS represent carbon and energy reserves for cells and are often excreted by microalgae as part of physiological processes or under stress conditions [12,21,[26][27][28], such as light intensity and light continuity, temperature [29,30], pH [31,32], excess, limitation or absence of nutrients, such as carbon, nitrogen, phosphorus, sulfur, sodium, potassium, iron, magnesium and calcium [14,33,34], and toxic substances [35,36], such as cadmium [37], copper, lead, chromium, nickel [31,38], and silver [39].…”

“…Therefore, there is an increase in the availability of nutrients and improvement in the soil's aggregate stability [86,87]. In addition, the different biological activities presented by EPS, such as antiviral and antibacterial [88], antioxidant [89], anti-inflammatory [90], immunomodulatory [91], and anticancer, indicate the potential of these compounds for application in various sectors such as food, cosmetics, pharmaceuticals, and biomaterials [14,20].…”

“…Microalgal EPS production depends on the microalgae species, cultivation conditions, or nutrient limitations such as nitrogen and phosphorus deprivation [12][13][14]. Furthermore, polysaccharides produced by microalgae can be classified based on their functionality: (i) structure of cell walls, (ii) storage (intracellular), and (iii) extracellular or exopolysaccharides, which are released into the environment.…”