Multi-objective tailored optimization deciphering carbon partitioning and metabolomic tuning in response to elevated...

Microalgae have garnered much contemplation as candidates to fix CO₂ into valuable compounds. Although microalgae have been studied to produce various metabolites, they have not yet proved successful for commercialization. Since, handling such problems practically requires satisfying multiple parameters simultaneously, we put forth a multi-parameter optimization strategy to manipulate the carbon metabolism of Scenedesmus sp. to improve biomass production and enhance CO₂ fixation to increase the production of fuel-related metabolites. The Box-Behnken design method was applied with CO₂ concentration, CO₂ sparging time and glucose concentration as independent variables; biomass and total fatty acid methyl ester (total FAME) content were analyzed as response variables. The strain is supplemented with both CO₂ and glucose with an aim to enhance carbon flux and rechannel it towards carbon fixation. As per the results obtained in this study, Scenedesmus sp. could effectively exploit high CO₂ concentration (15%) for longer duration under high concentration of glucose supplementation (9 g/L) producing a biomass of 635.24 ± 39.9 μg/mL with a high total fatty acid methyl ester (FAME) content of 71.29 ± 4.2 μg/mg, significant acetyl-CoA carboxylase enzyme activity and a favorable fatty acid profile: 35.8% palmitic acid, 10.5% linoleic acid and 30.6% linolenic acid. The carbohydrate content was maximum at 10% CO₂ sparged for the longest duration of 90 min under glucose concentration of 9 g/L. This study puts forth an optimal design that can provide evidence on comprehending the carbon assimilation mechanism to enhance production of biomass and biofuels and provide conditions to microalgal species to tolerate CO₂ rich flue gas.