Effects Of Different Nitrogen Concentrations On Growth And Lipid Accumulation Of Chlorella Emersionii

The word has been confronted with energy crisis for the depletion of conventional fossil fuel e.g coal, petroleum, natural gas ect. Much effects are seeking new energy to meet the needs of growing economy. Microalage is widely recoginzed as the most promising feedstock for biodiesel for its more rapid growth rate, higher oil content and non-competition with arable land usage compared with conventional biological feedstock. However, one of the major difficulties that hamper industrial application of microalage mass cultivation is the deficiency of fast-growing oleaginous and environmentally adapted algal strainas. In this study, several microalgae strains which living in natural water region, in Shanxi Province were isolated, purfied and evaluated. One of the strains with both higher biomass growth rate and lipid content was screed. These strains were characterized by morphological and molecular methods. Moreover, the effect of nitrogen concentration on the biomass and lipid accumulation of screened strain was investigated in order to futher improve the lipid productivity of the microalgae. The achieved main results were as follows:(1) Four kinds of microalage strains named C1,C2,C3,C4 were isolated from the sample collected from Shanxi Province and C3 had relative higher growth rate and oil content comparing with others. The biomass production rate and lipid productiion of C3 were 130 mg/L. D and 0.497 mg/L.D, respectively.(2) The strain C3 was identified through morphology and 18S rDNA sequences, indicating that it was a new strain of Chlorella emersionii.(3) For further improvement of oil production, the effect of NaNO3 concentration on the biomass and lipid accumulation of Chlorella emersionii was investigated. NaNO3 concentration in BG11 medium was set as 1 N (1.5g/L). The results showed that higher NaNO3 concentration was favorable for algae growth, however, nitrogen limitation stimulated the lipid accumulation.The highest lipid yield 540 mg/L was obtained under 1/2 N (0.75g/L) concentration and this lipid yield was about 1.6 times of that under 1N concentration.In conclusion, this study could provide theoretical and methodological foundation for the process control and mass cultivation of oleaginous microalgae.