Optimal Culture Conditions for Mycelial Growth and Exo-polymer Production of Ganoderma applanatum

Mushrooms are highly nutritious and may exhibit medicinal properties. In recent years, mushrooms have emerged as an important source of bioactive chemicals that have properties such as antitumor (Suzuki et al., 1989), immunological (Luettig et al., 1989), anti-complementary (Zhao et al., 1993), anti-inflammatory (Chihara et al., 1992), anticoagulant (Nishino et al., 1991), hypoglycemic (Yamada et al., 1989), hypolipidemic activity (Yang et al., 2000), mitogenic activity on lymphocyte (Jeon et al., 1998) and anti-viral (Rym et al., 1999). Ikekawa et al. (1969) published one of the first scientific reports on the antitumor activities of Polyporacease mushrooms. The three kinds of antitumor agent from mushroom polymers were developed: Krestin from cultured mycelia of Trametes versicolor (Ohno et al., 1976), Lentinan from fruiting bodies of Lentinus edodes (Chihara, 1992; Maeda and Chihara, 1971), and Schizophyllan from the liquid cultured broth product of Schizophyllum commune (Komatsu et al., 1969),. Mushroom polymers are mostly glucans with different types of glycosidic linkages, such as (1→3), (1→6)-β-glucans and (1→3)-α-glucans, but some are heteroglycans. Elfvingia applanata is a species of Basidiomycete, also called "Ganoderma applanata", which has been used in folk medicine for treating various ailments, including cancer (Makino, 1989). Recently, components of the modulate humoral immune response were detected in a purified fraction obtained from G. applanatum (Kim et al., 1994c). Later, anti-bacterial and antiviral activities of the aqueous extract of G. applanatum was reported (Kim et al., 1994b; Rym et al., 1999) without any toxicity (Kim et al., 1994a). Biologically active polymers can be obtained not only in fruiting bodies of mushrooms but also in submerged mycelial fermentations. Recently, the production of polymers from submerged mycelial cultures have been extensively exploited because they require fewer steps and because the purification process is simpler (Bae et al., 2000; Cavazzoni and Adami, 1992; Jong and Birmingham, 1992; Tseng, 1984). In the present investigation, therefore, the optimum culture conditions of Ganoderma applanatum for the mycelial growth and exo-polymer production were studied.