Enhanced arachidonic acid production using a bioreactor culture of Mortierella alpina with a combined organic nitrogen source

Abstract

The organic nitrogen source is one of the key factors affecting Mortierella alpina cell growth as well as arachidonic acid (ARA) production. The aim of the present work is to achieve an optimized recipe of organic nitrogen source for ARA production by M. alpina by testing four organic nitrogen sources. In the flasks, the results showed yeast extract or corn steep liquor were the most suitable sole nitrogen sources for biomass and ARA yield. In the bioreactor, a biomass of 17.5 g L−1 and an ARA yield of 2.7 g L−1 were achieved when using sole yeast extract, while cell autolysis was induced when using sole corn steep liquor; When using the combined nitrogen source with corn steep liquor and yeast extract at a 3:7 weight ratio, the biomass and ARA yield were significantly improved to 37 and 7.8 g L−1, respectively. This work evaluated whether using a mix of organic nitrogen sources could improve ARA production when scaling up from a flask to a bioreactor culture. The 3:7 ratio of corn steep liquor to yeast extract was quite favourable for large-scale ARA production, and as a result, this combination has great potential for improving fungal cultures.