Solid State Fermentation - In such fermentations, microbial growth and product formation occur at the surface of solid substrates. Examples of such fermentations are mushroom cultivation, mold ripened cheeses, starter cultures, etc. More recently, this approach has been used for the production of extracellular enzymes, certain valuable chemicals, fungal toxins, and fungal spores (used for biotransformation).

Traditional substrates are several agricultural products, rice, wheat, maize, soybean, etc. The substrate provides a rich and complex source of nutrients, which mayor may not need to be supplemented.