Effects Of Metal Ions On Lipid Production By Fermentation With Mortierella And Optimization Of Culture Conditions

Polyunsaturated fatty acids (PUFAs) play a significant role in human life and health, because they have so many physiological functions. Most of them are extracted from plants or fish oil. Due to the constraint of season, climate and production, it can not fully meet the demand of market. PUFAs from microbial fermentation can become an effective alternative source.Through18S rDNA and ITS sequences analysis, it indicates that the strain Haikou5is Mortierella sp.. Oil components analysis by GC-MS show that the oil is consist of polyunsaturated fatty acids (AA and gamma-linolenic acid), as well as a high content of hexadecanoic acid, octadecanoic acid,9-octadecenoic acid, docosanoic acid tetracosanoic acid and so on.By doing the single factor experiment of adding different concentrations of metal ions, Mg2+and Cu2+can’t get good results. Adding Ca2+at5X10-5mol/L, AA and GLA production were increased by21.65%and48.76%. Adding Fe2+at concentration of5X10-6mol/L, can get a precentage of AA at61.365, the AA yield is1.927g/L, content of GLA can reach13.553%, GLA yield is0.426g/L. Adding5X10-5mol/L Fe2(SO4)3, although the biomass is slightly inhibited, it can get a27.029%higher of AA production than the control. Adding Mn2+concentration at8X10-4mol/L, accumulation of biomass decreased slightly, but oil production (4.430g/L), AA production (2.708g/L) and GLA production (0.533g/L) can reach the maximum, we can reach the purpose of getting high-yield of GLA and AA. Adding Zn2+at1×10-3mol/L, percentage of AA is72.111, and production of AA is up to2.071g/L, it can reduce post-purification process and expenses, which will have good prospects for industrial production of AA. Adding ZnSO4at different day show us that:the second day to add will meet the largest growth inhibition, the third day adding will meet the biggest inhibition of GLA, and the fourth day will meet the maximum inhibition of AA. Adding MnSO4at the fifth day will get good results. The Orthogonal experiment of metal ions didn’t get good results.Experiments of different carbon sources indicate that the ideal carbon sources are2%dextrin,1%glucose and1%maltose,1.5%glucose plus0.5%sucrose,1%glucose plus1%starch,2%maltoseand, and2%glucose. The ideal nitrogen sources are2.5g/L soy flour,0.1g/L yeast extract,0.5g/L ammonium sulfate. Carbon and nitrogen sources orthogonal experimental results are not satisfactory, the entire batch experiments did not reach the effect of single factor experiments, but the production of AA is2-3times higher when compared with control. Turn to low temperature at the sixth day and culture for7days totally can get better results.