Study on the regulation of Mortierella alpina morphology and high yield of arachidonic acid by metal ions

Abstract

To achieve high production of arachidonic acid (ARA) through industrial fermentation of Mortierella alpina, the correlation between metal ions, mycelium pellet morphology and ARA production was investigated. By adding different metal ions to the culture medium, observing the morphological differences of mycelium pellet, total oil production and ARA content and established a correlation between them. The results showed that adding sodium ions increase the density of mycelium pellet, while reducing the diameter of mycelium pellet, resulting in a 41.59% increase in ARA production. Potassium ions, magnesium ions, calcium ions and iron ions slightly reduce the diameter of fungal hyphae and increase ARA production by 7.47%, 17.81%, 36.05% and 9.37%, respectively. At the same time, calcium ions promoted the branching growth of mycelium, which solve the problem of excessive free mycelium in fermentation broth within a certain concentration range. Zinc ions had a negative impact on bacterial growth, leading to the formation of mycelium clumps in the fermentation broth. Manganese ions and ferrous ions could transform the morphology of fungal mycelium into a smooth spherical surface, which was not conducive to the growth of M. alpina and the accumulation of oil. The comprehensive results showed that the optimal fermentation mycelium form for M. alpina was a dense central and loosely packed mycelium pellet. The yield of ARA was directly proportional to the density of mycelium pellet and inversely proportional to the diameter of mycelium pellet.

Funding

Scientific Research Fund Project of Education Department of Liaoning Province,(LJKZZ20220060)

Open Foundation of State Key Laboratory of Marine Food Processing & Safety Control,(SKL202306)

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