| Chlorella cell is a complete living organism,existing widely in the nature,which can be grown in the lakes,rivers,oceans and other water places.Most species of Chlorella grow in fresh water,due to the ability of high growth rate,easily cultivating,high nutritious values,effectively removing the nitrogen and phosphate in wastewater,and so on.Therefore,in recent years,Chlorella has been applied in developing fuels,purifying wastewater,and food and so on.The aim of this thesis is optimization of medium,ultraviolet mutagenesis,hydroxylamine hydrochloride mutagenesis,ultraviolet and hydroxylamine hydrochloride mutagenesis,and genome shuffling to get some strains of Chlorella vulgaris with high yield biomass.Furthermore,this study also investigates the effect of spermine or spermidine on the growth of Chlorella vulgaris.And it could promote the growth of Chlorella vulgaris by adding.The results are listed as follows:1.Five mediums were selected to culture the Chlorella vulgaris under heterotrophism.The medium 2 was the best for Chlorella vulgaris.,under this condition,biomass 11.5±0.05g/L,chlorophyll a 91.7±0.01mg/L,protein 39.66±0.2mg/g.The effect of glucose,sucrose,maltose,starch,and sodium carbonate,on the growth of Chlorella vulgaris was investigated to screen the best carbon source.The results showed that glucose enhanced the growth of Chlorella vulgaris comparing to other's carbon sources.2.The medium was optimized using uniform design method.Under this condition,the biomass of Chlorella vulgaris was 14.06 g/L,which was higher10%than before.3.Methods of mutagenesis were selected to screen and collect the strains of Chlorella vulgaris with high yield of biomass and high content of lipid.The conditions of UV mutagenesis were:time was 12 min,and the concentration of hydroxylamine hydrochloride was 1.2%.The results showed that the content of lipid and the biomass yield for Z2-137 strain were 6.05%and 15.63g/L,respectively,which were higher 61.33%and 22.11%than those of the control group.A strain named Y2-88 was collected using the method of hydroxylamine hydrochloride mutagenesis.The content of lipid and the biomass yield for Y2-88 were respectively higher 5.34%and 13.36%than before.A strain named H1-6 was collected using the method of mutagenesis of ultraviolet and hydroxylamine hydrochloride,giving the 2.36%lipid content and 14.83g/L biomass yield,respectively.4.The conditions were optimized to prepare the protoplast of Chlorella vulgar.The optimal conditions were:1.5%lywallzyme,1%cellulase,1%snailase,0.2%lysozyme,4h for hydrolysis,and 0.3mol/L NaCl.Under these conditions,the percentage for preparation of protoplast was 67%.The protoplast of Chlorella vulgaris would die by heating 20 min in 60? and 10 min under UV illumination.30%PEG solvent was added to suspension of protoplast and acquire a strain through genome shuffling.The highest biomass yield of Chlorella vulgaris was 16.52g/L,which was higher 31%than the control group.5.The influence of the different concentration of 0,5,10,20,40?g/mL of spermine or spermidine to the growth of Chlorella vulgaris were studied.The results showed that:The biomass of Chlorella vulgaris has been enhanced through adding spermidine in comparison to the control group.When the concentration of spermidine was 40 ?g/mL,it could greatly improve the growth of Chlorella vulgarisis.And after cultivation for 7d,the biomass yield and chlorophyll a of Chlorella vulgaris were 16.45g/L and 217.98mg/L,respectively. |
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