Isolation and Culture Condition Optimization of Chlorella vulgaris

Chlorella vulgaris Beyerinck (Beijerinck) is one of the fast growing planktonic microalgae predominantly found in lentic habitats. It was isolated from water samples using BG 11 medium and identified and screened for mixotrophic growth using glucose as carbon source in the medium. The growth of this algae was also studied for autotrophic and mixotrophic regimen. It showed higher growth in a medium of pH 7 containing glucose rather than in autotrophic condition. Similarly, its growth was also studied in media containing different nitrogen sources in which NaNO3 gave the best result. A pilot scale culture of C. vulgaris was performed in 5 l fermenter illuminated with fluorescent tube of 36 W maintaining 16:8 hrs of light and dark period with pH 7, temperature at 25°C, stirrer rate at 75 rpm, air flow rate at 30 L/hr. The specific growth rate was found to be 6.879 cells/ ml/ day whereas doubling time was found to be 2 hrs and 9 mins. The cells were harvested by sedimentation and centrifugation followed by drying at 50°- 80°C. The dried biomass was treated with dichloromethane: methanol (2:1) v/v solution in Soxhlet extractor for 3 DOI: http://dx.doi.org/10.3126/njst.v14i2.10414 Nepal Journal of Science and Technology Vol. 14, No. 2 (2013) 43-48