Chemical modulators as a strategy to enhance α-linolenic acid and α-tocopherol productivities in Scenedesmus sp.

• Chemical modulators can target specific algal metabolites • Fucose, β-ionone & ascorbic acid stimulated α-linolenic acid by ∼ 20.75 – 52.44 % • Kinetin & benzoic acid enhanced α-tocopherol productivity by ∼ 78.85 – 109.33 % • β-ionone, salicylic, and ascorbic acids can be economically attractive • Kinetin, 3-hydroxydecanoic acid, and oxaloacetate were deemed uneconomical High-value microalgal metabolites have attracted attention but been confined largely to lab scale experiments. A small number of success stories stand as a testimonial to the fact that, despite higher yields and promises of being sustainable, they are presently cost intensive and unattractive to the industry. This study attempts a media engineering approach using chemical modulators for targeted biomass and metabolite enhancement. We investigated 55 compounds over a 2-phase study for targeted improvements in biomass, α-linolenic acid (ALA), or α-tocopherol productivities. Salicylic, indole butyric, gibberellic, and benzoic acids stimulated growth by ∼ 12.43 – 20.28 % at concentrations of 20 – 1000 nM. Fucose, β-ionone, auxins, and gibberellic and ascorbic acids had ∼ 20.75 – 75.44 % better ALA productivity between 20 – 100 nM while β-ionone, kinetin, and benzoic acid stimulated α-tocopherol by ∼ 44.88 - 109.33 % at 100 - 1000 nM, compared to control. A basic economic analysis showed that biomass, ALA and α-tocopherol together could make the process economically attractive. Auxins, β-ionone, salicylic, and ascorbic acids were feasible considering the input cost vs. revenue generation potential while kinetin, cyanocobalamin, 3-hydroxydecanoic, folic, and oxaloacetic acids were deemed uneconomical. Chemical modulators as a strategy for targeted algal farming (Image made with BioRender.com)