The Prospects of Agricultural and Food Residue Hydrolysates for Sustainable Production of Algal Products

Abstract

The growing demand of microalgal biomass for biofuels, nutraceuticals, cosmetics, animal feed, and other bioproducts has created a strong interest in developing low-cost sustainable cultivation media and methods. Agricultural and food residues represent low-cost abundant and renewable sources of organic carbon that can be valorized for the cultivation of microalgae, while converting them from an environmental liability to an industrial asset. Biochemical treatment of such residues results in the release of various sugars, primarily glucose, sucrose, fructose, arabinose, and xylose along with other nutrients, such as trace elements. These sugars and nutrients can be metabolized in the absence of light (heterotrophic) or the presence of light (mixotrophic) by a variety of microalgae species for biomass and bioproduct production. The present review provides an up-to-date critical assessment of the prospects of various types of agricultural and food residues to serve as algae feedstocks and the microalgae species that can be grown on such residues under a range of cultivation conditions. Utilization of these feedstocks can create potential industrial applications for sustainable production of microalgal biomass and bioproducts.

Recycling Fermentation Strategy for Waste Cellular Residues in the Production of Polyunsaturated Fatty Acids

“…Improper disposal of these residues not only leads to environmental pollution but also represents a waste of valuable resources considering their nutrient content, including proteins, polysaccharides, and residual fatty acids. Recent studies have focused on the comprehensive utilization of this residual biomass, such as incorporating it into animal feed to provide proteins and fatty acids [6,19,20] or generating biogas through a biorefinery process [21]. Additionally, algal biomass can serve as organic fertilizer for agriculture [22].…”

Reduction of the Microbial Load of Digestate by the Cultivation of Galdieria sulphuraria Under Acidic Conditions

“…Even though the produced algal biomass obtainable by organic waste conversion can be rich in proteins and essential fatty acids [6,[10][11][12], and thus can potentially be considered as alternative protein source for food and feed purpose, its application is hindered by legislation. Whenever an organic material, which does not have food quality, is used in microalgae cultivation as nutrient source, produced biomass is banned from being used in food and feed formation [13].…”