Transcriptomic Analysis Of Biosy Nthesis And Regulation Of Eicosapentaenoic Acid Of Nannochloropsis Sp.PJ12 And Rhamnolipids Of Pseudomonas Sp.ZS1

Marine microorganism can produce a great variety of important bioactive compounds which are different from that terrestrial microorganism produce.As we all known,eicosapentaenoic acid(EPA)and rhamnolipid are beneficial for human health.However,the problems of high production cost and low yield limit their large-scale development and application,so how to improve the yield of compounds and reduce the production cost has always been a concern of researchers.The synthesis and regulation of these bioactive compounds are complex,which increases the difficulty to solve the problem.Therefore,the article regards Nannochloropsis sp.PJ12 with producing EPA and Pseudomonas sp.ZS1 with producing rhamnolipids as the research object,which is helpful to further understand related gene regulation and biosynthesis of the target compounds.The transcriptomic data of Nannochloropsis sp.PJ12 under nitrogen-deplete and nitrogen-replete conditions respectively were obtained from gene expression omnibus(GEO)database,then all data were de novo assembled and annotated.We gained 20,096 annotated ESTs and 4,651 differentially expressed ESTs.Based on reconstructing the metabolic pathways associated with EPA biosynthesis,the results showed that,under nitrogen-deplete condition,almost all of the enzyme activity in Calvin cycle,glycolysis and fatty acid synthesis were decreased,but most of enzyme activity were increased significantly in TCA cycle and ?-oxidation.It is worth noting that enzyme activity of?6 desaturase and ?15 desaturase in EPA biosynthesis were decreased significantly under the nitrogen-deplete condition.In addition,transcriptomic data of Pseudomonas sp.ZS1 cultured in mineral salt medium supplemented with 2%glucose or 2%yeast extract were obtained from GEO database,we performed transcriptomic analysis of Pseudomonas sp.ZS1 based on the obtained genomic information.We reconstructed related metabolic pathway of rhamnolipid biosynthesis,and the results showed that,under glucose condition,most of genes involved in Entner-Doudoroff pathway and biosynthesis of rhamnolipid and precursors significantly increase,but most of genes involved in TCA cycle significantly decrease.In the meantime,based on the transcriptomic data of Pseudomonas sp.ZS1,we proposed a new method that combining SPAdes and RAST was used to assemble and annotate transcriptome.We found that length correlation of gene between that this method produced and that method based on genome produced was 0.979.And comparing the result of metabolic pathway analysis,we found it is almost same with the method based on genome.In a word,through the transcriptomic analysis of Nannochloropsis sp.PJ12 and Pseudomonas sp.ZS1 in the article,the metabolic pathway of EPA and rhamnolipid synthesis was understood,and important genes affecting their biosynthesis were discovered,providing a reference for metabolic engineering for the overproduction of EPA and rhamnolipid.At the same time,a new method of transcriptomic analysis for prokaryotes provides a new clue to transcriptomic research.