In the experimental range, the lipid content of Chlorella sp. Y8-1 increased as the culture
period increased. In addition, the lipid content increased from 6.7 ± 3.9% to 31.5 ± 3.18% of dry cell weight as the urea was increased from 0 to 0.25 g/L; however, the lipid production was
limited when the urea concentration was higher than 0.5 g/L. The maximal lipid content (31.5 ± 3.18% of dry cell weight) was obtained in the medium containing 0.25 g/L of urea (Fig. 4).