Domestication of the high-sugar-tolerant Mortierella alpina on arachidonic acid (ARA) production

Abstract:

[Objective] In order to improve arachidonia acid (ARA) production, and prevent the degeneration of ARA-producing strain Mortierella alpina in long-term culture preservation and cultivation, which could lead to low consumption rate of substrates like carbon source. [Methods] Mortierella alpina strain was first domesticated in high-sugar PDA plate with gradient sugar content (2%、5%、7%、10% and 15%). The strain which grew better in the solid medium containing 10% sugar was then selected and transferred to two liquid high-sugar media with different nitrogen sources to domesticate. The gradient sugar contents were 3%、4%、5% and 6%, respectivlely. Finally, the domesticated strain was used to produce ARA in a 2 L bioreactor. [Results] The experimental results show that the consumption of sugar increased from 3 g/(L·d) up to 12 g/(L·d) in the medium with yeast extract, and from 7 g/(L·d) up to 12 g/(L·d) in the medium with corn steep liquor. After cultivation for 144 h in a 2 L bioreactor, the yield of ARA reached 8 g/L, which was 4 times higher than that obtained with the original strain. [Conclusion] The domestication of the high-sugar-tolerant Mortierella alpina increased the consumption of sugar, biomass, total fatty acid and ARA production. The domesticated strain could maintain the high sugar resistance in the preserving process and turn to be more stable.