The Primary Research Of Microalgae Nannnochloropsis Sp. Culture And Extraction Of Its' PUFAs

With the use of ocean resources being more and more paid attentions, the research of algae' cultivation and purifying it's biological active substance, especially the found of the PUFAs' physiological function being proved by the scientists, has become the hotspot in the world widely, as the algae is one of the most important resources in the ocean.The article primarily explores the cultivation of a microalgae which is a new style Kelly single microalgae Nannochloropsis sp., in flask ,3l and 20L photobioreactor and the extraction and enrichment of Polyunsaturated fatty acids (PUFAS), which were 16:2,16:3,18:2 and 20:5 fatty acids(e.g. 16:2 means there were 16 carbons and 2 double bounds in the carbon chain of the fatty acid) by urea complexion, in order to provide new ways for the use of algae PUFAs.(1) In the cultivation of the Nannochloropsis sp., cultivation condition is inoculation concentration 63±3 mg/L(dry biomass weight), ventilation flux 400 ml min-1, and luminous intensity 70.8 μmol photon m-2 s-1. It has been found that the carbon resources influence the biomass in the cultivation, and adding glucose can enhance the biomass obviously. Through the research , the biomass in the 3L airlift circumfluence photobioreactor can reach 857.1 mg DW l-1 after 8d by mix-cultivate. In the scale cultivation in 20L airlift photobioreactor, the biomass is 633.1 mg l－1 in the 10d by mix-cultivate. So scale cultivation of the Nannochloropsis sp. still has limits. And for the biomass in the flask,3L photobioreactor and 20L photobioreactor, the models for the cell growth has been built. The values according to the models are answered for the values measured in the experiments. (2) In the research of PUFAs' extraction and enrichment from the algae Nannochloropsis sp.. in the experiment we choose grinding for cytocrosis, petroleum benzin-ether for extraction and methanol-KOH for saponification. The ratio value of the cytocrosis can reach 65%, and in the extractive experiment, the best technological conditions we select are V(petroleum benzin)/V(ether) 2/1, temperature 20℃ and extraction for 5h. There is good result of gas chromatograph of the lipid, without tailed peak and time-lag in the chromatograph peak.In use of the method of urea complexion to purify the PUFAs, the saturated and low-unsaturated lipids can be removed well. We put the emphasis in the concentration of the urea-methanol, and when the mass concentration is 20%, The mass of the PUFAs purified is about 90% of the total lipid extracted.