Arachidonic acid synthesis by glycerol-grown Mortierella alpina

Microbiological production of physiologically active AA usually used carbohydrates as substrates. Recently, glycerol attracted attention as a promising renewable substrate for biotechnological industry. The effect of pure glycerol on the growth, lipid synthesis, and AA production by earlier selected Mortierella alpina strains LPM-301 and NRRL-A-10995 was studied. It was shown that AA amount varied from 22-29 to 63-68% of lipid in dependence on the initial glycerol concentration in the medium. The transition from glycerol- to nitrogen limitation of the growth was accompanied by a reverse correlation between lipid content of biomass and AA level of lipid. Under selected optimal conditions (nitrogen limitation of fungal growth at glycerol concentrations of 75-81 g/L), AA production by 14-day cultures reached 40-43% of lipid and 11-13% of biomass indicating that glycerol can be successfully used as a carbon substrate for AA production. Practical applications: AA has found wide application in medicine, pharmacology, diet, and infant nutrition as a precursor of several key eicosanoid hormones and pharmacologically active metabolites. It can also be used in agriculture as an elicitor of plant resistance to phytopathogens. Microbiological processes for AA production usually used carbohydrate substrates. Results of this study indicate that AA can be produced from glycerol, which is known as a promising renewable carbon substrate. Under selected optimal conditions (nitrogen limitation of fungal growth at glycerol concentrations of 75-81 g/L), AA production by Mortierella alpina strains LPM-301 and NRRL-A-10995 reached 40-43% of lipid and 11-13% of biomass. These values are comparable with those obtained for carbohydrate-grown Mortierella fungi.