| 论文摘要： |
A unicellular marine diatom, Entomoneis sp. MMOGRB 0374S, was isolated as a candidate strain for high production of a polyunsaturated fatty acid (PUFA), arachidonic acid (ARA, 20: 4 omega 6). Its morphological characters were typical for representatives of the genus Entomoneis, e. g. junction line, sigmoid keel and panduriform girdle view. This species was differentiated from other Entomoneis species by its smaller size and denser stria. Phylogenetically, it was distinct from other taxa with a long branch. This relationship was also emphasized by only 94% nucleotide similarity between Entomoneis sp. MMOGRB 0374S and other related species. The biomass concentration reached 182 mg l(-1) at the stationary phase and 229 mg l(-1) after 3 days of nitrogen-limited culture. Lipids were extracted using four methods, and the dichloromethane (DCM)/methanol method was the most effective, yielding 36% of dry biomass at the stationary phase and 40% after 3 days of nitrogen-free culture. Gas chromatography revealed 17 types of fatty acids. ARA was the major component of PUFA and represented between 16% and 19% of the total fatty acids using the four lipid extraction methods, among which DCM/methanol yielded the highest proportion of ARA. Considering the yields of both total lipids and ARA, the DCM/methanol method was the most effective for ARA extraction. |
