Mushrooms are the members of higher fungi, belonging to the class Ascomycetes (e.g. Morchella, Tuber, etc.) and Basidiomycetes (e.g. Agaricus, Auricularia, Tremella, etc.). They are characterized by having heterotrophic mode of nutrition. According to Chang and Hayes (1978) edible mushroom refers to both epigeous and hypogeous fruiting bodies of macroscopic fungi that are already commercially cultivated or grown in half culture process or implemented under controlled conditions. They are rich in protein and constitute a valuable source of supplementary food. Some of them are deadly poisonous, for example Amanita verna, A. virosa, etc.
Use of mushrooms can contribute positively in facing the challenge of world-wide food shortage, originating with rapidly expanding human population at the rate of more than 2 lakh per day. Mushrooms are rich in protein and other accessory compounds. Their value as food accessory is beyond the computation of the chemists and physiologists. They are among the most appetizing of the table delicacies and aid greatly to palatability of many food when cooked with them, for example Morchella esculenta, Agaricus bisporus (syn. A. compestris), Tuber sp. etc. (Atkinson, 1961).
Mushroom cultivation was thought to be very simple, but infact it is a complicated business. Yield is affected by compost, spawn, temperature, moisture, etc. There has been extensive concern in recent years, as far as production of food protein from domertic, agricultural and industrial wastes is concerned. On the other hand, high and sophisticated technology in the yeast and algal cultures for SCP demands complicated input requirements and large capital. The immediate products may even need to be processed before being accepted as human food. The great value in promoting the cultivation of mushrooms lies in their ability to grow on cheap carbohydrate materials and to transform various waste materials (Chang and Li, 1982).