3. Solid versus liquid fermentation

Fermentation in liquid media is particularly well-suited to cultures of single-celled micro-organisms, such as bacteria and yeasts, whereas fermentation in solid media is well-suited to mycelial organisms. Indeed, the agitation required to homogenize liquid media (and oxygenate them for aerobic cultures) results in shear stresses that few mycelial strains are able to withstand (although fungal strains have been successfully adapted to this type of culture). What's more, there are no oxygenation constraints in solid-state fermentation, as the mycelium is in direct contact with atmospheric oxygen.

Naturally, this type of fermentation has found the most applications in fungal mycelial production.

The first non-food applications were for enzyme production, essentially for the production of enzymes that hydrolyze plant polymers. These enzymes...