Dynamic Allocation Of Carbon Flux Triggered By Task-Specific Chemicals Is An Effective Non-Gene Disruptive Strategy For Sustainable And Cost-Effective Algal Biorefineries

Chemical molecules such as butylated hydroxyanisole (CBHA), propyl gallate (CPG), and acetylcholine (CACH) enhance cell growth and/or lipid productivities effectively at the nanomolar concentration (100 nM) in microalgae Scenedesmus dimorphus UTEX1237. The biomass and lipid productivities were improved by 11% (181.60 +/- 1.94 mgL-1d-1) and 48% (18.71 +/- 0.20 mgL-1d-1), respectively, with biomass yields reaching up to 2 g L-1 in CBHAtreated cells compared to Control (Co; 163.62 +/- 1.57 mgL-1d-1). In contrast, CACH-treated cells have 41.38% (33.04 +/- 0.30 mgL-1d-1), 25.24% (15.88 +/- 0.14 mgL-1d-1) and 117% (4.38 +/- 0.00 mu gL-1d-1) higher productivities of carbohydrates, lipids, and tocopherols, respectively compared to Co. However, optimum proteins have been observed in forskolin (CFORS) treatment (59.15 +/- 1.83 mgL-1 d-1). The metabolomic analysis illustrates the role of CBHA in the rerouting of carbon flux towards lipids and/or sterols, by enhancing the accumulation of glycolysisbased metabolite, namely acetic acid. At the same time, CACH downregulates it by improving pyruvic acid. In contrast, a citric acid cycle metabolite 2-ketoglutaric acid is downregulated in CACH. These modulators target specific pathways in a given condition to initiate the biosynthesis of metabolites. For instance, Brefeldin (CBREF), Jasmonic acid (CJA), and CACH showed enhancement in total tocopherols and beta-carotene. In contrast, all other modulators except CBHA and CACH were also involved in increasing the total carotenoid productivity. Henceforth, such media engineering perspective demonstrates the utilization of specific chemicals to dynamically divert the carbon flux towards the biosynthesis of unique metabolites, an effective non-gene disruptive strategy for sustainable and cost-effective algal biorefineries.