Screening Microalgae for Producing Biofuel Precursors from Industrial Off-Gases

The capture and conversion of industrial off-gases into valuable biomass using microalgae represents a promising strategy for CO2 mitigation and sustainable production of biofuels and biochemicals. In this study, fifteen (15) microalgal strains were screened and evaluated for their growth performance and the accumulation of macromolecules like polysaccharides and lipids under CO2-enriched conditions, simulating the off-gas composition of an operational 2G biorefinery producing bioethanol from wastes. It was found that Stichococcus sp. exhibited the highest polysaccharides accumulation (33% w/w) in biomass, while Chlorella vulgaris demonstrated superior lipids content (34% w/w). Both strains (coded as wild-AUTH) displayed robust growth, each achieving biomass concentrations of 1.5 g/L of Dry Cell Weight (DCW), while maintaining tolerance to the gas feedstock. The protein contents of the strains further support their potential integration into a 3G biorefinery framework, where advanced biofuels could be one of multiple valorization pathways. These findings underline the feasibility of using microalgae as a retrofitting solution for bioethanol and other bioenergy plants, enhancing CO2 capture while enabling biofuel production. The top-performing species provide a basis for optimizing bioprocess parameters and scaling up the cultivation in industrial photobioreactors (PBRs) to improve productivity and commercial applicability.