Effects of Different Light Spectrums on Growth, Chlorophyll and CO₂ Biofixation Capacity of Chlorella sp.

Air pollution, increased traffic, and the extensive use of fossil fuels have led to elevated atmospheric CO₂ levels, undermining efforts to mitigate climate change. This study investigates the effect of different light spectra, on the growth performance and bioenergy potential of Chlorella sp. The strain was cultivated in BG11 medium under controlled conditions (25 ± 2 °C, 25 µmol/m²/s) for 15 days, exposed to monochromatic LED lights emitting blue, white, red, or green wavelengths. Growth parameters including optical density (OD₆₀₀), dry biomass (X), chlorophyll content (chl a+b), specific growth rate (μ), maximum biomass productivity (Pₘₐₓ), and CO₂ biofixation rate (FCO₂) were evaluated. The results demonstrated that red light significantly enhanced biomass accumulation (0.710 g/L), chlorophyll concentration (0.871 µg/mL), and CO₂ bio-fixation rate (0.0117 mg CO₂/d), outperforming other spectral conditions. Green light also supported notable growth, while blue light was the least effective. These findings contribute to optimizing light-driven cultivation strategies for sustainable microalgal biomass production and CO₂ mitigation in bioenergy applications