| Object: Desert algae were isolated and purified from Gurbantunggut Desert and Taklimakandesert algae. Isolated species were identified by combining method of morphology andmolecular biolog,Collection Plenty of unique Desert algae resources;At the same time, in thisstudy, screening a strain of heterotrophic microalgae from algaes has been isolated at ourlab., its biochemical component content and change in different cultivation way and differentgrowth period were compared.9desert algaes of a cDNA Mixed library was constructed,partial of accD and Pepc2genes fragments that is related to synthesis of lipid metabolismwere cloned, This work set the molecular basis for further studies on desert alge to betterunderstand the relationship between the accumulation of grease and the synthesis of lipidmetabolism.Methods:(1)Sand sample were collected from desert, through the BBM medium are mixedculture, then microalgae mixed suspension was separated and purified by plate method andthe96-well plate gradually dilution. Microalgaes that was isolated were identified by methodof morphology and molecular biology(18S rDNA,5.8S rDNA-ITS,16S rDNA data);(2)Separation of algae strains: Total lipid was determined by acid hydrolysis, fatty acidcomposition was determined by GC-MS method.(3) Screening of a strain of heterotrophicmicroalgae GTD8A1, Total lipid was determined by spectrophotometry, the content of crudeprotein was determined by Coomassie brilliant blue method, the fatty acid composition wasanalyzed by gas chromatography.Results and Conclusion:1. The separation and purification of11strains of desert microalgae,5strains were collected fromGurbantunggut Desert,6strains were isolated fromTaklimakan desert.By morphology and18S rDNA data identification, results showed that10strains belong to Chlorophyta, amongthem5strains belong to the Chlamydomonadaceae,1strain belongs to the Protosiphon genus,2strains belonging to the Chlorella genus,1strains belong to Klebsormidium genus,1strainbelongs to Scenedesmaceae,but not clear to its the genera; the other1strain belongs to thecyanobacteria nostoc genus. The5.8S rDNA-ITS sequence of4kinds of microalgae ofisolated species was amplified and analysed, the result suggested, TLD2A1and GTD2A2respectively with Chlorella sp. and Chlamydomonas debaryana may be the same species,TLD7A2and TLD7B-5blast large sequence differences were not identified to species.16SrDNA data show that TLD5A1cyanobacteria nostoc genus.2. In7strains of desert microalgae samples,The highest crude lipid content in the microalgaesamples is17.7%(%of cell dry weight) which belongs to Chlorella TLD6B, biomass of Klebsormidium genus is the highest (up to0.346g/L),total lipid content of3strains ofChlamydomonas are lower.6strains of microalgae samples of fatty acid compositioncontaining C16-C18fatty acids, but fatty acid composition and content of different algae isdifferent. The other1strain TLD7B-5were rich in long chain fatty acid C20-C24(77.9%).3. Screening of1strains of heterotrophic desert microalgae GTD8A1, growth ability with glucoseand sodium acetate as external carbon was best In different culture condition, biomassincrease2-4times than autotrophic．Gas chromatography analysis showed that fatty acidwere mainly C16-C18Under different culture conditions, content of C18:3(n3) about up to70%of the total fatty acid in autotrophic, saturated fatty acids and single unsaturated fattyacid ratio increased in mixotrophic and heterotrophic culture, the proportion of of C18:3(n3)reduce.4. A cDNA Mixed library of9desert algaes was constructed, The titer of the unamplified construct ed cDNA library was1×10~6pfu/mL, A cDNA library consisting of2.5×10~6aboveclones, the empty transformants without cDNA insert is3.89%of totaltransformants,redundant:12.26%, full-length rate:51.47%. Pepc2and accD patial fragmentwas cloned. this work set the molecular basis for further studies on desert algae to betterunderstand its the synthesis of lipid metabolism... |
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