Unravelling the potential of seven microalgae species: nutritional, antioxidant, and antimicrobial properties and application

Featured Application: The present study highlights the rich biochemical profiles and bioactivities of seven microalgal species and their respective extracts, emphasizing their broad and versatile range of potential applications. These microalgae serve as promising sources of valuable biomolecules, notably proteins, especially in Limnospira sp., and lipids, with Nannochloropsis sp. being particularly rich in the latter. Limnospira sp. generally exhibited the strongest antioxidant activity and demonstrated good antimicrobial properties, while Nannochloropsis sp. showed the most pronounced antimicrobial effects against the majority of tested bacterial strains. These species hold significant potential across various sectors, from sustainable nutrition (e.g., functional foods, aquafeeds) and therapeutics (e.g., pharmaceuticals, wound care), as well as in next-generation cosmetics, bio-based industrials, and environmental bioremediation—placing them at the forefront of green biotechnological innovation. A specific application explored in this work involves the development of an edible film incorporating lipid- and bioactive-rich extracts from Nannochloropsis sp. and a bioactive-rich extract from Limnospira sp., which could be used in active food packaging. The implementation of integrated biorefinery approaches is expected to enhance the commercial viability and sustainability of these microalgae. In conclusion, the seven microalgae and their extracts investigated in this study present sustainable and multifunctional solutions for the health, nutrition, cosmetic, and environmental sectors. Their inherent bioactivity and compositional versatility continue to stimulate growing interest in biotechnological development and commercial exploitation. Microalgae are a rich renewable source of a wide variety of bioactive compounds. This study focuses on seven microalgae—Limnospira sp., Dunaliella sp., Lobosphaera sp., Nannochloropsis sp., Odontella sp., Porphyridium sp., and Tetraselmis sp.— analyzing their nutritional compositions and the potential bioactivity of their hydroethanolic extracts obtained via ultrasound-assisted extraction. The total phenolic content (TPC) and antioxidant activity (ABTS, DPPH, and ORAC), as well as the antimicrobial activity of the extracts were determined. The protein content of the microalgae ranged from 22.9 ± 0.1 to 59.8 ± 1.6%, the fat content ranged from 5.3 ± 0.0 to 36.6 ± 0.0%, and the carbohydrates ranged from 24.0 ± 3.0 to 46.1 ± 1.0%. The highest contents of protein, fat, and carbohydrates were found in Limnospira sp., Nannochloropsis sp., and Lobosphaera sp., respectively. The TPC of the extracts varied between 0.53 ± 0.09 and 3.18 ± 0.53 mg GAE/100 mg DW. Antioxidant activity values ranged from 1.09 ± 0.15 and 2.85 ± 0.45 μmol TE/100 mg DW for ABTS, 0.25 ± 0.06 and 2.28 ± 0.06 μmol TE/100 mg DW for DPPH, and 2.37 ± 0.58 and 18.32 ± 1.00 μmol TE/100 mg DW for ORAC. The extract from Limnospira sp. exhibited the highest antioxidant activity and also showed notable antimicrobial effects. Meanwhile, the Nannochloropsis sp. extract demonstrated the strongest antimicrobial activity against most tested bacterial strains. Lipids were successfully extracted from Nannochloropsis sp. Furthermore, alginate and zein films incorporated with bioactive-rich extracts from Limnospira sp. and Nannochloropsis sp., along with the lipid-rich extract from Nannochloropsis sp., were developed. These films showed significant antioxidant activity and effective antimicrobial activity against Listeria monocytogenes.

Keywords

Antimicrobial activity Antioxidant activity Arthrospira Dunaliella Edible film Limnospira Lobosphaera Microalgae Nannochloropsis Nutritional composition Odontella Porphyridium Tetraselmis