Protein, fatty acid, and pigment content of Chlorella vulgaris under different light regimes

The effects of irradiance and photoperiod on growth rates, chlorophyll a, β-carotene, total protein, and fatty acid content of Chlorella vulgaris were determined. The maximum growth rate (1.13 day−1) was at 100 μmol photons m−2 s−1 and 16:8-h light/dark photoperiod. Chlorophyll a and β-carotene contents significantly differed under different light regimes with chlorophyll a content lower at high irradiance and longer light duration, while β-carotene showed the inverse trend. The total protein and fatty acid content also significantly differed in different light regimes; the maximum percentage of protein (46%) was at 100 μmol photons m−2 s−1 and 16:8 h photoperiod, and minimum (33%) was at 37.5 μmol photons m−2 s−1 and 8:16 h photoperiod; the total saturated fatty acids increased, while monounsaturated and polyunsaturated fatty acids decreased with increasing irradiance and light duration.