The Synthesis Of Polyunsaturated Fatty Acids From Phaeodactylum Tricornutum

Long-chain polyunsaturated fatty acids play an important role in human health.Particularly eicosapentaenoic acid(EPA)and eicosapentaenoic acid(DHA)have significant effects on brain function development and cardiovascular disease.Phaeodactylum tricornutum is a kind of marine diatom with no odor,easy culture,fast reproduction and rich EPA content.It is also an ideal model organism to study EPA synthesis.The molecular mechanism of accumulation EPA and DHA synthesis of Phaeodactylum tricornutum from molecular biology is very valuable to improve EPA and DHA yield.The main research contents and results of this article are as follows:1.Download the whole genome sequence of Phaeodactylum tricornutum from the NCBI database,and select members of the elongase gene family containing the conserved domain sequence of ELO(Pfam number PF01151),and analyze their structural characteristics and encoded protein sequences by bioinformatics.It was found that a total of 6 ELO gene family members were identified from the Phaeodactylum tricornutum genome sequence,of which 4 are PUFA substrate specific genes and 2 are SFA / MUFA substrate specific genes.The difference in the number of amino acids is not obvious,including 1 to 3 exon regions,all of which are presumed to be hydrophobic proteins,and 6 ELO genes are distributed on 5 chromosomes.They all contain multiple transmembrane regions and phosphorylation sites,and there is no signal peptide sequence.The cis-acting elements of the ELO gene family promoter contain multiple light-responsive elements,hormone-responsive elements,and other abiotic stress-responsive elements.2.The CDS sequence of ?5-elongase gene was cloned by molecular biological means.the recombinant plasmid was constructed p Pha-T1-5e,and the recombinant plasmid was overexpressed by electrotransformation.through ble resistance screening and PCR sequencing validation,three transformed algal strains(E51?E52?E53)were screened.the results of fatty acid determination showed that the DHA content of E51?E52?E53 three transformed algal plants increased by 26.4%,44.7% and 27.3%(P<0.05),respectively,compared with wild algal plants.the fluorescence quantitative PCR detection showed that E51 ? E52 ? E53 gene expression increased by53.9%,54.2%,50.75%(P<0.05),respectively.3.Investigate the effects of light,temperature,-N ?-P ?-Si on fatty acid accumulation in Phaeodactylum tricornutum.the results showed that the EPA content increased by 18.9% under the condition of weak light intensity(2000 Lux)compared with the control group(4000 Lux).the higher the light intensity,the lower the EPA content.the EPA and PUFA contents gradually increased with the decrease of culture temperature under different culture temperature conditions.Under N and P culture conditions,the EPA content decreased compared with the control group,while the SFA and MUFA content increased significantly;under culture conditions,the EPA content was higher than the control group at the 12 th day,and 11.2% higher than the control group.4.Through the ARTP mutagenic treatment of wild algal plants,the mutagenic algal plants with fast birth rate and relatively high EPA content were screened by primary screening and re-screening,among which the EPA content of mutagenic algal plants was23.4% and 38.0% higher than that of wild algal plants,respectively.