Screening Of High-yield Lipids Microalgae And Optimizing Of Culturing Conditions For Microalgae Oil-production

With the rapid development of global industry, people’s energy demand alsocontinued to increase. However, due to the limitation of fossil energy, people have tofind renewable energy. Biodiesel is a kind of fattyacid methyl ester which canreplace diesel. It obtains from biology.This study screened two kind of rich lipids-microalgae from seawater. In thisstudy, f/2medium was used to cultivate microalgae. The influence of a single factor(pH, N, Si²⁺, Mg²⁺, Fe³⁺or Zn²⁺concentration of f/2medium) on the growth and theoil content of microalgae were explored. Nile Red was used to detect the lipid contentof microalgae at the same time. And then determine the optimal cultivation condition.The growth and the oil content of Chlorella sp. does not change significantly inpH6.5⁸.5. Chlorella sp. showed the highest biomass in3.0mmol/L NO^3-. The oilaccumulation of Chlorella sp. was better in0.6mmol/L NO^3-. Chlorella sp. presentedfast-growing under high concentration of Fe³⁺. High Zn²⁺inhibited its growth and oilaccumulation. In contrast, low Zn²⁺promoted its growth and oil accumulation.Biddulphia sp. had high oil content in4.8mmol/L NO^3-and it reached the bestcondition at the12day of0.3mmol/L NO^3-. Biddulphia sp. showed the bestcondition of growth in pH8and the highest oil content in pH6. Biddulphia sp.presented fast-growing under high concentration Fe³⁺, but it had little influence tothe oil content in0.01～100μmol/LFe³⁺.Biddulphia sp. presented fast-growingunder concentration3.0mmol/LMg²⁺.The growth and the oil content of Biddulphiasp. reached the best condition in1.74umol/L Zn²⁺. High Zn²⁺inhibited its growth.The oil content of Biddulphia sp. reached the best condition in0.07mmol/L Si²⁺inthe day11to13.The factors affecting the growth and oil-production of microalgae were optimizedby orthogonal experimental design. And the result showed that the optimalcultivation condition for Chlorella sp. was a group of factors containing0.9mmol/L Mg²⁺，pH8.5，12μmol/L Fe³⁺,7.2μmol/L Zn²⁺and0.3mmol/L NO^3-. The optimalcultivation condition for Biddulphia sp. was a group of factors containing pH9,0.5mmol/L Mg²⁺,0.3mmol/L NO^3-,1.74μmol/L Zn²⁺,0.07μmol/L Si²⁺and100μmol/L Fe³⁺.