Efficient production of arachidonic acid by Mortierella alpina through integrating fed-batch culture with a two-stage pH control strategy

Abstract

Arachidonic acid (ARA) yield and productivity of Mortierella alpina mutant D20 were enhanced by integrating a fed-batch culture combined with a two-stage pH control strategy. Following a kinetic analysis of the whole fermentation process, a two-stage pH control strategy was developed in which the pH was maintained at 5.5 for the first 48h and then shifted to 6.5 till the end of fermentation. Using this strategy, a maximum ARA production of 8.12g/L was achieved. On the basis of pH control, the effects of fed-batch cultures on ARA productivity were further investigated. A maximum ARA productivity of 1.40g/L/d was obtained with a two-stage constant-speed glucose feeding strategy, starting with a glucose concentration of 50g/L. This strategy was simple and economical to operate, and it may be possible to apply this approach for large-scale industrial production of ARA.