Studies on power plant alga for lipid production and assessment of growth kinetics under photo-heterotrophic growth

Microalgae-derived biochemicals and biofuels offer a sustainable alternative to petroleum-based products, with algal lipids being highly valuable due to their energy content and renewable characteristics. In this study, the lipid production potential and growth and lipid production kinetics of Leptolyngbya subtilis JUCHE1 under photo-heterotrophic conditions have been investigated using glycerol as a carbon source. The concentration of glycerol was systematically varied from 0.04 g/L to 0.15 g/L (Equivalent to C-concentrations for different inlet-CO₂ concentrations in the gas phase i.e. 5-20%v/v). The growth behaviour of L. subtilis JUCHE1, including the values of biomass concentration and specific growth rate were found to be 0.81 g/L and 0.71 d⁻¹ respectively. The findings demonstrate that L. subtilis JUCHE1, a power plant blue-green alga, shows adaptability to utilize an organic carbon source (glycerol) instead of its usual substrate i.e. inorganic carbon source (CO₂). The incorporation of glycerol enhances the growth and lipid yields of L. subtilis JUCHE1, offering a cost-effective and environmentally friendly approach. The kinetics follow both the Monod model and Luong type power law model in uninhibited (up to 0.11g/L glycerol) and inhibited growth regimes respectively having µ_max, K_S, and K_I values of 0.88 d⁻¹, 0.03 g/L, and 0.49 g/L. The lipid generation is growth-associated and kinetics follow the Luedeking Piret model. The characterization of lipids produced by Leptolyngbya subtilis JUCHE1 under heterotrophic conditions shows the presence of many valuable biochemical like Eicosenoic acid, Hexadecenoic acid, Glycidol, Palmitoleic acid, and Oleic acid to name a few.