论文部分内容阅读
Nannochloropsis oculata CS-179,a marine eukaryotic unicellular microalga,is rich in long-chain polyunsaturated fatty acids (LC-PUFAs).Culture temperature affected cell growth and the composition of LC-PUFAs.At an initial cell density of 1.5 × 106cell mL-1,the highest growth was observed at 25 ℃ and the cell density reached 3 × 107 cell mL -1 at the beginning of logarithmic phase.The content of LC-PUFAs varied with culture temperature.The highest content of LC-PUFAs (43.96％) and EPA (36.6％) was gained at 20℃.Real-time PCR showed that the abundance of A6-desaturase gene transcripts was significantly different among 5 culture temperatures and the highest transcript level (1 5℃) of Nanoc-D6D took off at cycle 21.45.The gene transcript of C20-elongase gene was higher at lower temperatures (10,15,and 20℃),and the highest transcript level (20℃) of Nanoc-E took off at cycle 21.18.The highest conversion rate (39.3％) of A6-desaturase was also gained at 20℃.But the conversion rate of Nanoc-E was not detected.The higher content of LC-PUFAs was a result of higher gene transcript level and higher enzyme activity.Compared with C20-elongase gene,A6-desaturase gene transcript and enzyme activity varied significantly with temperature.It will be useful to study the mechanism of how the content of LC-PUFAs is affected by temperature.