Efficient arachidonic acid-rich oil production by Mortierella alpina through a repeated fed-batch fermentation strategy

• Different strategies were conducted to shorten the ARA-rich oil fermentation period.
• Repeated fed-batch (RFB) strategy shortened the fermentation period significantly.
• RFB proved to be of great potential for the large-scale ARA-rich oil fermentation.
• This work offered enlightenment for the other long time needed fermentations.

Arachidonic acid (ARA)-rich oil production by Mortierella alpina is a long fermentation period needed process due to the low growth rate of the filamentous fungus used. This causes the low productivity of ARA-rich oil and hinders its industrial mass scale production. In the present study, different fed-batch strategies were conducted to shorten the fermentation period. The result showed that compared with the batch culture, the fermentation period was shortened from 7 days to 5 days with the productivity of ARA-rich oil increased from 0.9 g/(L·d) to 1.3 g/(L·d) by using the fed-batch fermentation strategy. Furthermore, repeated fed-batch fermentation strategy was adopted to achieve the purpose of continuous production. By using this strategy, the fermentation period was shortened from 40 days to 26 days in a four cycle repeated fed-batch fermentation. This strategy proved to be convenient and economical for ARA-rich oil commercial production process.