Efficient production of arachidonic acid of Mortierella sp. by solid-state fermentation using combinatorial medium with spent mushroom substrate

Solid-state fermentation (SSF) is a bioconversion process for turning cheap agro-industrial materials to added-value products. For enrichment of agro-industrial materials with arachidonic acid (ARA; C20:4 n-6), SSF process of Mortierella sp. was developed by optimizing cultivation medium and parameters. The results showed that the fungal cultivation on the medium with optimal ratio of selected agricultural materials provided the fermented mass containing high ARA proportion of total fatty acid. Inclusion of the optimal medium with suitable amount of spent mushroom substrate, which was used as an internal support, significantly promoted the ARA production yield. Using the predicted quadratic model generated by Box–Behnken design, the maximal ARA production yield was achieved, thereby the fermentation parameter set for ARA production was experimentally validated using the developed medium formula. Of variables studied, the culture temperature and initial moisture content were important for the ARA production. The developed SSF process would provide a prospect for larger scale production of ARA by this fungal strain.