From emissions to innovations: integrated algal biorefinery for CO2 sequestration and metabolomics-guided profiling

Abstract

The rapid increase in the concentration of the most significant greenhouse gas, CO2, predominantly driven by anthropogenic activities, has heightened the worldwide need for sustainable, nature-based carbon sequestration strategies. Over the past few years, microalgae have been scrutinized by the research community and have emerged as promising candidates for CO2 mitigation, as well as bioproduct generation. This is due to their remarkable photosynthetic efficiency, rapid proliferation, and potential to convert CO2 and energy into algal biomass and high-value metabolites. However, amidst the increasing emphasis on CO2 mitigation strategies via microalgae, research gaps exist that hinder the adaptation of a sustainable circular biorefinery approach that incorporates CO2 mitigation, microalgae-assisted wastewater treatment, and bioproduct formation. To begin with, limited knowledge of the physiological and metabolic response of the indigenously isolated microalgae to nutrient availability, coupled with elevated CO2. Furthermore, studies focused on systematically optimizing CO2 sparging conditions, such as aeration rate, sparging concentration, and sparging duration to improve the carbon fixation efficiency of microalgae while minimizing energy requirements, are very scarce. Subsequently, the application of untargeted metabolomics to investigate the metabolic reprogramming of microalgae under CO2 supplementation and its translation into the valorization of organic waste to produce essential bioproducts remains underexplored. The present thesis focuses on addressing these significant bottlenecks by evaluating the CO2 capture and utilization dynamics, metabolic signature, and bioproduct generation ability of an indigenously isolated microalga, Scenedesmus sp., from the Indore region, India.