Nutritional value, antimicrobial and antioxidant activities of micro- and macroalgae, single or blended, unravel their potential use for aquafeeds

• Published in: Journal of applied phycology 2021-12, Vol.33 (6), p.3507-3518
• Main Authors: Ferreira, Mariana, Teixeira, Carla, Abreu, Helena, Silva, Joana, Costas, Benjamin, Kiron, Viswanath, Valente, Luisa M. P.
• Format: Article
• Language: English
• Subjects: Algae; Amino acids; Antiinfectives and antibacterials; Antimicrobial activity; Antimicrobial agents; Antioxidants; Aquaculture; Aquaculture feeds; Arachidonic acid; Bacteria; Bioactive compounds; Biological activity; Biomedical and Life Sciences; Carbohydrates; Chlorella; Chlorella vulgaris; Disease resistance; Ecology; Economics; Eicosapentaenoic acid; Fatty acids; Fish; Fish farms; Freshwater & Marine Ecology; Life Sciences; Lipids; Lysine; Marine crustaceans; Nannochloropsis oceanica; Natural products; Nutrients; Nutritive value; Pathogenic bacteria; Plant Physiology; Plant Sciences; Proteins; Scavenging; Seaweeds; Shellfish; Synergistic effect
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-021-02549-2

Algae are natural products with great potential as aquafeed ingredients, being rich in nutrients and bioactive compounds. They can improve fish health while being sustainable at social, economic, and environmental levels, contributing to the one health concept. In this study, two micro- ( Nannochloropsis oceanica and Chlorella vulgaris ) and two macroalgae ( Gracilaria gracilis and Ulva rigida ), produced under commercial conditions, were selected to unravel their nutritional value (protein and lipid content; fatty acid and amino acid profiles), as well as antimicrobial activity against farmed fish and shrimp pathogenic bacteria and bioactive potential by assessing ABTS + • and DPPH • scavenging capacities. A commercial blend of these algae (ALGAESSENCE™—Feed) was included to determine possible synergistic effects. Nannochloropsis oceanica was rich in eicosapentaenoic acid and arachidonic acid (ARA) and G. gracilis had high content of ARA. Chlorella vulgaris had the highest levels of essential amino acids (EAAs), namely lysine. The blend is a well-balanced and rich source of proteins, lipids, essential fatty acids, EAAs and carbohydrates. The single algae and the blend displayed bactericidal and bacteriostatic activities against most of the tested pathogenic bacteria, with the most promising results being observed against Tenacibaculum maritimum (40–45% activity). In some cases, the micro- and macroalgae had no simultaneous bactericidal and bacteriostatic activities, but the blend was able to both kill and inhibit the growth of those bacteria. The algae had also some antioxidant activity, with G. gracilis and the blend presenting the highest values. The present results showcased the blend as a promising ingredient to be included in aquafeeds.