Optimization of lipid production from seaweed mannitol by engineered Yarrowia lipolytica strains

Journal article, 2026

Brown algae represent an abundant and renewable marine biomass rich in carbohydrates, including mannitol, which can be a by-product of the industrial alginate extraction. This study explores the potential of valorizing seaweed-derived mannitol for lipid production using genetically engineered Yarrowia lipolytica strain. The modified strain AJD Delta EYD1 DGA1, lacking erythritol dehydrogenase (EYD1) and overexpressing diacylglycerol acyltransferase (DGA1), efficiently converted algal mannitol into single-cell lipids. Various pretreatment methods mimicking industrial alginate extraction were tested to assess their impact on mannitol recovery and yeast performance. Among tested conditions, soaking algae in 1% citric acid yielded the highest mannitol concentration (14.76 g/L) and supported efficient growth and lipid accumulation. The process was successfully scaled up to 1 L bioreactors. Fatty acid analysis revealed oleic acid (C18:1) as the predominant component (constituting on average 48% of the overall produced lipids), with monounsaturated fatty acids constituting over 60% of total lipids. The results confirm that engineered Y. lipolytica strain can efficiently utilise algal mannitol and convert it into lipids in a higher laboratory scale, offering a sustainable route for integrating alginate production with microbial oil bioprocesses. Further optimization of carbon-to-nitrogen ratios and continuous feeding strategies could enhance lipid yield and process scalability.