Optimizing production of polyunsaturated fatty acids in Marchantia polymorpha cell suspension culture

Chlorophyll containing callus cells of Marchantia polymorpha are able to grow under dim illumination in the presence of an organic carbon source and retain the ability to produce polyunsaturated fatty acids (PUFA), including C(20) fatty acids. Highest PUFA production was achieved using 2,4-dichlorophenoxyacetic acid as growth regulator. Inoculum size, illumination intensity, organic carbon source, and ferrous ion are the major factors affecting PUFA productivity. Maximum PUFA productivity is attained under low light intensity, with a photon flux density ca. 20 micromol m(-2) s(-1). Optimal inoculum size and glucose concentration for PUFA production are 8-12% and 20-30 g l(-1), respectively. Ferrous ion can promote PUFA productivity by increasing the intracellular lipid content. Highest productivities for PUFA, arachidonic acid (ARA), and eicosapentaenoic acid (EPA) were 35.0+/-2.1, 6.7+/-0.4 and 6.6+/-0.4 mg l(-1) day(-1), respectively. PUFA production in the M. polymorpha culture is shown to be strongly growth-associated. Environmental stress (osmotic pressure) is ineffective in promoting PUFA productivity. Chitosan, an elicitor, also has no effect on intracellular PUFA content in cultured M. polymorpha cells.