Optimization of light intensity on growth rate and total lipid content of Chlorella vulgaris

Abstract

Chlorella vulgaris was a potential microalga as a source of biomass due to its high lipid content. This study aimed to determine the growth and total lipid content of C. vulgaris that cultured in different light intensity. There were four-level treatments of light intensity applied i.e.: 2,500; 5,000; 7,500 and 10,000 lux, and were replicated three times. Microalga C. vulgaris was cultured in the plastic container, 35-40 ppt salinity, moderately aerated, kept in 19-25 C temperature, and pH 8-10 in the laboratory. The light intensity was given continuously for 24 hours. The culture media was enriched with Walne's fertilizer (1 ml/l media). The period of culture was 12 days and growth was measured as cell density. The harvested microalga was dried, and the total lipid was then determined. Total lipid content was determined by the gravimetric method. Results showed that there were significant differences (p≤0.05) in the growth among four-level treatments of different light intensity, as well as for the total lipid content (p≤0.05). The best total lipid content was reached from sample at 10,000 lux (17.40±0.52% dry weight), followed by 7,500 lux (15.06±0.25% dry weight), 5,000 lux (13.3±0.43% dry weight) and 2,500 lux (7.30±0.30% dry weight), respectively.