Sucrose non-fermenting 1-related protein kinase 2-14 participating in lipid elevating efficacy and biodiesel upgrade by Coccomyxa subllipsoidea

Microalgae-based biodiesel offered a promising solution to mitigate environmental and energy crises, yet improving lipid productivity and upgrading biodiesel quality in microalgae remained a challenge. Abscisic acid (ABA) supplementation to Coccomyxa subllipsoidea resulted in lipid accumulation, and most sucrose nonfermenting 1-related protein kinase 2 (SnRK2) family genes especially SnRK2-14 containing cis-acting element for ABA responsiveness in region of promoter showed significant up-regulation and strongly positive correlated with lipid productivity. Therefore, this study was the first to explore the lipid elevating efficacy and biodiesel upgrade by SnRK2-14 overexpression in C. subllipsoidea. The lipid yield of SnRK2-14 overexpression C. subllipsoidea strain (SnRK2-14-OCS) boosted to 2.18 g/L, representing a 2.63-fold improvement over wild type (WT). Further, SnRK2-14 overexpression up-regulated lipid-related genes, rewired intermediates/energy derived from protein and carbohydrate degradation, and inhibited lipid oxidation by strengthening antioxidant capacity to collectively achieve lipid overaccumulation in SnRK2-14-OCS. Under fed-batch fermentation mode, the lipid yield further increased 7.92-fold in SnRK2-14-OCS compared to WT and also modulated fatty acid profiles to upgrade biodiesel quality to meet the established quality criteria. These findings revealed the involvement of SnRK2-14 in lipid biosynthesis in microalgae and highlighted the potential of manipulating SnRK2-14 for improved lipid and biodiesel production.