Abstract:
This research studied the effects of light wavelength and aeration rate on growth and carotenoid production in green microalgal Chlorococcum humicola. Results of batch cultivation in 1-L Duran bottle recommended using white light at 5,000 lux until the end of exponential phase as compared to other light wavelength, with 601 mg/L of the dry weight concentrations. Application of white light at 105 lux along with blue light at constant power of 6 W led to the increased carotenoid production during stationary phase measured at 7.96 mg/g-dw (i.e., 4.67 mg/L), which 12% higher than applying only white light at 105 lux. Subsequent experiment aimed to select suitable photobioreactor which focus on suspensioning of biomass. The results indicated that airlift photobioreactor was more suitable for C. humicola cultivation than bubble column photobioreactor for the aeration rates from 0.1 to 1.25 vvm, and moreover, the aeration rate at 0.8 vvm yielded the highest cell growth and carotenoid concentrations. Finally, cultivation of C. humicola was conducted in the airlift photobioreactor using all findings described previously. The cultivation in airlifit photobioreactors using aeration rates of 0.8 vvm and white light at 5,000 lux during the exponential phase followed by the white light at 105 lux and blue light at constant power of 6 W during stationary phase yielded cell dry weight at 880 mg/L, which were greater than the results from Duran bottles, while increased carotenoid concentrations measured as high as 7.81 mg/g-dw (i.e., 6.87 mg/L), yet statistically insignificant different (p>0.05) from the results from Duran bottle.