## 4 Conclusions  
The findings of the present study demonstrate that the investigated microalgae represent promising sources of valuable macronutrients: _Limnospira_ sp. exhibited the highest protein content; _Nannochloropsis_ sp. was particularly rich in lipids; and _Lobosphaera_ sp. had a high carbohydrate content. _Nammochloropsis_ sp. also showed the highest energy value among the species studied. Ultrasound-assisted hydroethanolic extraction yielded microalgal extracts with varying degrees of bioactivity. Overall, _Limnospira_ sp. demonstrated the most favorable combination of antioxidant and antimicrobial activities, while _Nannochloropsis_ sp. exhibited the strongest antimicrobial effects against most of the tested bacterial strains. A promising and innovative direction involves combining extracts from two or more microalgae species to leverage synergistic effects. Edible films composed of alginate and zein, enriched with bioactive-rich extracts from _Limnospira_ sp. and _Nannochloropsis_ sp., as well as a lipid-rich extract from _Nannochloropsis_ sp., were successfully formulated. These films exhibited notable antioxidant activity and effectively inhibited the growth of _Listeria monocytogenes_. Thus, edible films incorporating lipid-rich extracts from _Nannochloropsis_ sp. and bioactive-rich extracts from _Limnospira_ sp. show promising potential for active food packaging. In summary, the microalgal extracts obtained in this study show strong potential for applications as natural preservatives in food products (e.g., incorporated in bread, cookies, and pasta), particularly via incorporation into edible films and coatings. For the validation and practical implementation of the results of this study, the different microalgal extracts could, for example, be used in food product formulations as food additives, nutraceutical ingredients, or functional food components. To enable real-world application, first, formulation studies are recommended to ensure the extract stability, compatibility, and sensory acceptability in target products. Next, pilot-scale trials should be performed to test production scalability and consistency. Finally, regulatory and safety requirements could be met through toxicological assessments and compliance with relevant food or health product regulations. The studied microalgae represent, therefore, a valuable and sustainable source of multifunctional solutions for health, nutrition, cosmetics, and environmental sectors (e.g., eco-friendly packaging), highlighting their role in green biotechnological innovation and commercial viability. Exploring inter-species combinations may unlock next-generation applications that outperform single-extract solutions in both efficacy and commercial value. Conceptualization, A.M.M.B.M. and R.M.S.C.M. ; methodology, V.F.R.M., A.I.L., A.M.M.B.M. and M.P. ; software, V.F.R.M. ; validation, A.M.M.B.M. ; formal analysis, V.F.R.M., and A.M.M.B.M. ; investigation, V.F.R.M. and A.I.L. ; resources, M.P., A.M.M.B.M., R.M.S.C.M., D.G., C.P., S.M.B. and L.C. ; data curation, V.F.R.M. ; writing--original draft preparation, V.F.R.M., and A.M.B.M. ; writing--review and editing, A.M.M.B.M. and R.M.S.C.M. ; visualization, V.F.R.M., and A.M.M.B.M. ; supervision, A.M.M.B.M., R.M.S.C.M. and M.P. ; project administration, A.M.M.B.M., R.M.S.C.M. and M.P. ; funding acquisition, R.M.S.C.M. and M.P. All authors have read and agreed to the published version of the manuscript. This work was supported by National Funds from FCT--Fundacao para a Ciencia e a Tecnologia through Project UIDB/50016/2020 and by project EXTRATOTECA--COMPETE2020 POCI-01-0247-FEDER-033784. [PERSON] acknowledges FCT for the PhD research grant with reference UI/BD/152825/2022. Not applicable. Data Availability Statement: Data are contained within the article. Further inquiries can be directed to the corresponding authors. The authors declare no conflicts of interest.