Influence Of External Conditions On The Fatty Acid Expression And Omics Analysis Of Mortierella Alpine

Mortierella alpine,which was general recognized as safe(Gras),received extensive attention for production of polyunsaturated fatty acids.Gas chromatographic method for detection and analysis of fatty acid composition was established.Fatty acid expression affected by exogenous conditions(precursors and temperature)were investigated.Transcriptomics and metabolomics were studied while M.alpine was incubated at different temperatures.The main conclusions are as follows:(1)A method for fatty acid component detection was established by Sp-2560 column.The accuracy and reliability were analysed by T test and the relative standard deviation.(2)The biomass,fatty acid content,and components of M.alpine were investigated after added different vegetable oils and Twains to the culture.The results indicated that not only the fatty acid content but also the arachidonic acid content were increased.Compared with the control group,the production of arachidonic acid reached to 2063.2 mg/L,2062.8 mg/L and 2192.9 mg/L when rapeseed oil,linseed oil and soybean oil were added as the precursor respectively,which improved 1.13?1.26 times.The arachidonic acid content improved to 88.46%as 1744.9 mg/L.However,the fatty acid content was decreased,when Tween 80 was used as the precursor.(3)Fatty acid composition were analysied by the established method when M.alpine incubated at room temperature and low temperature.At low temperature,the proportion of polar lipid was significantly higher(25 ? the 82.48%neutral lipids,polar lipids 17.51%;15 ? the neutral lipids 57.10%,42.90%polar lipids);EPA was synthesied and the proportion of AA in polar lipids and neutral lipids were reduced when M.alpine incubated at low temperature.AA converyed to EPA for the activity of ?17 desaturase increased at low temperature.Thoses fatty acids 18:0,18:1 and 20:0 that have higher saturation were converted to polyunsaturated fatty acids,such as 18:2,18:3 and 20:3 at low temperature,which have beneficial for M.alpine adapt to the environment of low temperature.(4)The genes transcriptional level of key enzymes and the synthesis of fatty acids affected by these changes were studied by transcriptome sequencing when M.alpine incubated at room temperature and low temperature conditions.AA converyed to EPA for the gene transcription level of ?17 desaturase increased at low temperature,while the others enzymes' gene transcription levels that involved in PUFAs synthesize were reduced;Changes of key enzymes' gene transcription levels that including glycolytic pathway,TCA cycle and glycerides pathway were discussed,the impact of changes related to fatty acid synthesis in genes transcription levels of those enzymes were analysed.From the point of gene transcription level,at low temperatures,glycolytic pathway and TCA cycle provided acetyl coenzyme A and NADPH for the synthesis of fatty acid;glycerol in the pathway of glycerolipid synthesis reduced while the synthesis of phospholipid increased.(5)Changes of metabolites were detected by GC-TOFMS while M.alpine incubated at different temperatures.Differences in metabolites were analysed by modeling analysis of PCA,PLS-DA and OPLS-DA.Difference obvious metabolites were screened combine with transcriptome analyzes.Myristic acid and palmitoleic acid content significantly increased at low temperature,while a significant reduction in the content of oleic acid and eicosenoic acid.