Mutant Breeding Of Gamma Linolenic Acid Produced Strsin Mortierella Isabella

Gamma- linolenic acid(GLA) as essential fatty acids involved in the composition of the cell membrane, is a direct precursor of prostaglandin(PG), thromboxane A2(TxA2) and leukotriene(LT). Gamma- linolenic acid plays an important role in the human body hormones and fatty acid metabolism, especially in the prevention and treatment of cardiovascular disease, diabetes complications, characteristic of eczema, viral infections and cancer. Traditionally, γ- linolenic acid is mainly derived from plants, and γ- linolenic of microbial oil becomes more and more popular due to the limitations of research resources and the environment in recent years.In this paper, Mortierella Isabella As303410 was taken as the original strain, and mutagenesis and screening criteria lithium chloride complex by UV mutagenesis was used to determine the best screening system. Mutagenesis conditions: the amount of lithium chloride 3 g / L, UV mutagenesis time 30 s; maleic hydrazide resistance screening maleic hydrazide in the medium dosage 40 mg / L, Mortierella mold in the fatty acid desaturase enzyme assay conditions pH8.4, temperature 35 ℃, 2, 3, 5-Triphenyltetrazolium chloride(TTC) added amount of 0.8%, time 1h. Mutation screening of the optimized conditions, after repeated Mutagenesis get an inheritance stable γ- linolenic acid linolenic acid producing strain F312. Its γ- linolenic acid production reached 1236 mg / L, which increased by 70% compared with the original strain(725 mg / L).The nutrients of promoting gamma-linolenic acid production have been found by studying Mortierella isabellina produce γ- linolenic acid metabolic regulation. Plackett-Burman(PB) design and Central Composite Rotatable(CCRD) design were applied to screen and optimize the nutrients. Glucose, KNO3, sodium acetate, sodium citrate, as four key factors were found to be significant to PB design and the following statistic analysis. By CCRD design and response surface analysis the quadratic model for the four significant factors were established with γ- linolenic acid yield as the target response. Comprehensive PB design and CCRD design the optimum medium formula were glucose 100.90 g/L, KNO3 1.57 g/L, sodium acetate 3.42 g/L, sodium citrate4.56 g/L, yeast extract 3.75 g/L, KH2PO4 2.25 g/L, MgSO4?7H2O 0.6 g/L, Ca Cl2 0.3 g/L, FeSO4 0.15 g/L, Zn SO4 0.2 g/L. Under optimal conditions γ- linolenic acid yield was up to 1500.73 mg/ L, and it increased by 21% compared with that(1236 mg/L) before optionization.