Microalgal Lipid Profile and Their Dietary Impact on Drosophila melanogaster

Background/Objectives: Microalgae are gaining increasing attention as sustainable sources of dietary lipids and other bioactive compounds; however, the relationship between microalgae lipid composition and physiological outcomes in vivo remains insufficiently understood. This study aimed to characterize antioxidant activity, total lipid content and fatty acid (FA) profiles of selected freshwater microalgae and to evaluate their dietary impact using Drosophila melanogaster as a whole-organism model. Methods: Four freshwater microalgal species (Chlorella vulgaris, Nannochloris limnetica, Scenedesmus communis, and Tetradesmus obliquus) were cultivated separately in 3N-BBM+V medium under controlled laboratory conditions. DPPH, FRAP and TPC were measured in microalgae methanolic extracts. Total lipids were extracted using a modified Breuer method and quantified gravimetrically. FA profiles were determined as fatty acid methyl esters by GC-FID. Freeze-dried microalgal biomass (3 mg/mL) was incorporated into standard D. melanogaster diet. Lifespan and body mass were assessed separately in females and males, as well as fecundity in general. Results: Total lipid content ranged from 17.3% to 28.1% of dry weight, with FA profiles dominated by C16 saturated, monounsaturated (omega-9), and omega-6 polyunsaturated fatty acids. Correlation analysis indicates that antioxidant properties of the studied microalgae are more closely linked to lipid fractions than to phenolic content. Dietary supplementation with microalgal biomass of three out of four microalgal species significantly extended median lifespan, particularly in males, without adverse effects on body mass or fecundity. Conclusions: These findings indicate that freshwater microalgae can serve as a physiologically safe dietary lipid source. D. melanogaster represents a suitable in vivo model for screening the nutritional potential of microalgal lipids.