Cultivation Of Chlorella And Shudy On The Conditions Of Lipid Production

Due to the shortage of useable fossil energy and deterioration of ecological environment,looking for a clean, new type of biological energy has become the top priority. As a single-celledalgae with rich and important physiological functions, chlorella has been widely used in many fields.In recent years, the research of Chlorella oil production has more and more attention. However,because of limit to large-scale cultivation technology and cost question, chlorella oil is difficult toachieve scale and industrialization.The purpose of this paper is to select the higher algae strains through the experiment, andfurther to study the best conditions of its growth and oil accumulation. It is helpful to explore thedevelopment and utilization of chlorella. The main results are as follows:1. Through autotrophic and heterotrophic culture, Chlorella sorokiniana, as a aglal strains withhigh reproductive and rich high lipid were screened out.2. The results of heavy metal stress show that Hg is the most important factor affectingChlorella autotrophic culture among the three metals of Hg, Pb, Cd. These three heavy metalsinhibited significantly chlorophyll a, and the law of impact on chlorophyll a is line with growth ofchlorella. Low concentrations of heavy metals increase activities of protective enzymes in chlorella,while high concentrations of heavy metals inhibit the activities of protective enzymes.3. The best carbon, nitrogen source and the ratio of carbon and nitrogen are sucrose, NH4NO3and30:1in heterotrophic cultivation, respectively. In the case of the same carbon content, the highernitrogen content is, the higher degree saturation of lipid could be.4. The effects of trace elements were also studied in promoting its growth and lipidaccumulation in Chlorella. Low concentrations of Fe3+can promote the growth of C. sorokinianawhile the high concentrations will inhibit the gowth of C. sorokiniana. Mn2+has a little influence tothe growth of C. sorokiniana. However, Zn2+has no influence to the growth of C. sorokiniana. Thelipid accumulation occurs in early and middle phases, while the lipid content increase little in latephase. Fe3+had great effect on the lipid accumulation of C. sorokiniana in early phase, but littleeffect on the lipid accumulation at late stage. Similarly, Zn2+also has great significance to the lipidaccumulation. However, Mn2+has little significance to the lipid accumulation of C. sorokiniana.Furthermore, the result showed that C. sorokiniana has19kinds of fatty acids. Particularly, thepercentage of C16:0and C18:0were significantly higher than other fatty acids, the next is C18:2. Moreover, those three trace elements can influnce the proportions of saturated fatty acids andunsaturated fatty acid at the same length of carbon chain, but can not change the length and contentof carbon chain.5. The experiment of phosphorus or sulfur missing shows that the element missing can reducethe cell density of the chlorella. The sulfur missing can effectivetly promote the lipid content inchlorella. Further, the result shows that C. sorokiniana includes16kinds of fatty acids. Particularly,the percentage of C16:0and C18:2were significantly higher than other fatty acids, the next is C18:0or C18:3. Moreover, the unsaturated fatty acids are1.5times the saturated fatty acids whenthe cultivation condition is elements missing.Chlorella growth of C. sorokiniana the best carbon and nitrogen sources were sucrose andNH4NO3, optimum C: N is30:1, added the1×10-3mmol/L Fe3+，0mmol/L Zn2+，1×10-3mmol/LMn2+to the medium or reduced the content of sulfur and phosphorus which all can improve the lipidcontent of Chlorella.