Study on improved arachidonic acid production by Mortierella alpina with dynamic temperature-control in airlift bioreactor

Constant and dynamic temperature-control was inverstigated for efficient arachidonic acid (ARA) production by Mortierella alpine in different fermentation scales and environments. The results showed that airlift bioreactor was more suitable for ARA production process compared with mechanical stirring fermentor.Meanwhile, cell growth rate showed to be optimum at 25℃, while ARA ratio in lipid showed to be maximal at16℃. As a result, a dynamic temperature-control strategy, in which the culture temperature was controlled at25℃ at the first 72 h and linearly decreased 1.5℃ for every 12 h till 16℃, then kept at 16℃ for the rest of the fermentation, was developed in the airlift bioreactor. With this control strategy, the ARA production level reached4.7g/L which was increased 38.2% compared with the level of constant temperature (25℃) control strategy.