Effects of N and C Sources On Growth, Chlorophyll a, Lipid and CO2 Biofixation for Chlorella Vulgaris

In this report, the effects of different concentrations of N and C sources on Chlorella vulgaris cultivated in a bubble column photobioreactor were studied. Four N levels (0.5, 1.0 and 1.5 mM for basic medium and 10 mM for N-8 medium) were respectively tested. The results for basic medium showed that when cells stayed in the exponential growth phase, nitrogen had been depleted below 0.1 mM. However, for N-8, when cells entered the stationary phase, the N level was still kept above 1.0 mM. Additionally, the maximum chlorophyll a content would decrease with N consumption (< 0.1 mM) when C. vulgaris was cultured in basic medium, but keep stable in N-8 medium. The growth of microalgae in different concentrations of CO2 (0.7%, 3%, 6% and 9%, V/V) was investigated. The results showed that CO2 biofixation rate had a reverse relationship with CO2 concentration, and the variation of biofixation rate and chlorophyll a kept the same tendency. We also obtained the data of lipid content in different N and C sources.