Arachidonic Acid Fermentation

Arachidonic acid(AA) is a C-20 polyunsatured fatty acid and has several unique biological activities. AA fermentation by microorganisms has recently attracted great interest. In this paper, the breeding of high AA yield strains using Mortierella sp. as original strain was studied and fermentation conditions, aging of harvested mycelium and fermentation kinetics were investigated.Mortierella sp. was mutated in twice by UV and screened with asparin at lower temperature. A mutant strain Mortierella sp. M10 which could accumulated AA in large quantities was obtained. The results of primary fermentation showed that the dry cell weight(DC) and total lipids(TL) were 31g/l and 8.3g/l by Mortierella sp.MlO, but only 20.3g/l and 5.4g/l by original strain.According to the studies of the effects of several cultural conditions (i.e. temperature, culture time, pH, carbon source, nitrogen source, vegetable oils et. al.) on the mycelium growth and lipids accumulation, the optimum medium of the Mortierella sp. M10 was determined. Under the optimum culture conditions the dry cell weight(DC) and the production of AA reached 43g/l and 1.25g/l resepectively for 5L fermentor by feeding culture of glucose.By means of the investigation of the effects of several aging conditions(i.e. aging temperature, aging time and original pH, et al.) on the lipid content in mycelium, we found that when the Mortierella sp.M10 mycelium harvested after 5 days culture was aged 10 days at 25℃, the AAweight in dry mycelium increased from 2.44g/l to 3.07g/l.The quadratic polynomial equation mathematical models for the effects of carbon source and nitrogen source on DC was developed. The residual...