Journal of CO2 Utilization (Jun 2024)
Novel paradigm of light and CO2 feeding to improve the co-production of astaxanthin and polyunsaturated fatty acids in Haematococcus pluvialis
Abstract
This study aimed to develop an innovative paradigm of lighting and CO2 flow rate in dilution and photoinduction stages of H. pluvialis cultivation to overcome the cell number reduction and stimulate the astaxanthin and polyunsaturated fatty acids accumulation joined by carbon bio-sequestration. The appropriate paradigm of lighting to reach the maximum cell number, astaxanthin concentration, and astaxanthin content in the dilution and photoinduction stages was obtained 2-fold (300 µmol/m2/s) and 6-fold (900 µmol/m2/s) of the final light intensity in the phototrophy stage (150 µmol/m2/s), respectively. Under the inventive lighting paradigm, feeding the 225 mL/L/min CO2 recorded optimum consequences in the dilution and photoinduction stages. The cell number, astaxanthin productivity, lipid content, polyunsaturated fatty acid and CO2 bio-fixation rate at the end of the photoinduction stages by lighting/CO2 balance were 94 %, 96 %, 32 %, 61 % and 40 % higher than control, respectively. Additionally, the levels of omega-6 fatty acids and omega-3 fatty acids were 70 % and 73 % higher than the control, respectively. This substantial increase was achieved by maintaining an optimal ratio of omega-6 to omega-3 fatty acids (3.05). Furthermore, to maximize the cell growth of microalgae and enhance the accumulation of valuable metabolites through CO2 bio sequestration, it is recommended to focus on the CO2 flow rate parameter instead of the CO2 percentage. That is affected by both the CO2 percentage and the aeration rate. Our findings provide a promising cost-effective and ecofriendly approach to improve the co-production of astaxanthin and polyunsaturated fatty acids in H. pluvialis.
