Bioprocess strategies for enhancing biomolecules productivity in Chlorella fusca LEB 111 using CO₂ a carbon source

The aim of this study was to evaluate the influence of different carbon dioxide (CO₂ ) concentrations on the distribution of carbon forms in the culture medium and the biomass production and biomolecules productivity of the strain Chlorella fusca LEB 111. In this study, experiments were carried out in which C. fusca cultures were exposed to different CO₂ concentrations, 0.03% (0.08 ml_CO2 ml_medium^-1 days^-1 ), 5% (0.18 ml_CO2 ml_medium^-1 days^-1 ), and 15% vol/vol CO₂ (0.54 ml_CO2 ml_medium^-1 days^-1 ). Among the carbon chemical species distributions in the culture medium, bicarbonate was predominant (94.2-98.9%), with the highest quantitative percentage in the experiment receiving a 15% CO₂ injection. C. fusca LEB 111 cultivated with 15% CO₂ showed the highest biomass productivity (194.3 mg L^-1 days^-1 ) and CO₂ fixation rate (390.9 mg L^-1 days^-1 ). The carbohydrate productivity in the culture that received 15% CO₂ was 46.2% higher than the value verified for the culture with the addition of CO₂ from the air (0.03% CO₂ ). In addition, CO₂ concentration providing increases of 0.03-15% to C. fusca cultures resulted in a 31.6% increase in the lipid productivity. These results showed that C. fusca can be used for CO₂ bioconversion and for producing biomass with potential applications for biofuels and bioproducts.