1. Introduction
Ganoderma lucidum that has been used for centuries is a fungus used as a health food and medicine in the Far East. This mushroom is considered to be a popular folk medicine for treating various diseases such as hepatitis, hypertension, hypercholesterolemia, gastric cancer, arthritis and bronchitis. Recent studies of this fungus have revealed its various appealing biological activities, including anti-tumor , hypoglycemic activity , anti-inflammatory effects and cytotoxicity toward hepatoma cells. Many investigations have also suggested that the extracellular polysaccha- ride, 1,3-β-d-glucan, produced by G. lucidum has potential to become a new carcinostatic agent that may be useful in immunotherapy. G. lucidum is traditionally cultivated in solid culture. This method of production has several disadvantages, including the long time required to cultivate the fruiting body of G.lucidum, the difficulty of controlling the quality of the product,and the ease with which the culture is affected by the environmental changes. Recently, submerged fermentation technology for mycelial cultures of G. lucidum has been developed, and attracted much attention as a promising alternative because it has none of the weaknesses stated above. In commercial applications, most related products emphasize simultaneously the amount of mycelium and the dose of polysaccharide in their granules. Therefore, an effi- cient process for simultaneously producing cellular materials and polysaccharide must be developed.