Responses of mycelia of Ganoderma lucidum to vanadium, selenium and germanium were examined over a wide range of concentrations (10-1,120 pg/ml) in pure culture. Se and V were found to be highly toxic, but Ge was not toxic at the levels tested. Ganododerma lucidum cultivated on substrates of sawdust with V (30-80/~g/g) developed mature fruitbodies, but the bioaccumulation of V was quite low (2.5-7 pg/g in pileus, 12.5-21.5 Fg/g in stipe and < 1 ~g/g in basidiospores). Se as Na2Se04 labeled with 75Se was effectively taken up from substrates and accumulated in fruitbodies (mainly in pileus), then depleted by discharge of basidiospores. Ge as GeCI4 labeled with 77Ge was easily uptaken and translocated into fruitbodies.Key Words--accumulation; Ganoderrna lucidurn; germanium; selenium; vanadium.The trace elements in fungi are a neglected area of study, and data on responses of higher fungi to such elements are scant. For example, selenium (Se) has been studied sporadically in mycology for its distribution in fungal biomass and its effects on fungal growth and development. On the other hand, it is regularly reported to be present in bioactive antioxidants and to be an important microelement in foods, whose deficiency in the diet results in serious heart diseases (Ferretti and Levander, 1976 (Bao and Thuy, 1983). Although vanadium (V) is widely distributed in nature, particularly in sea ecosystems, data on V in fungi are very few, whereas its bioactivity in mammalian, namely, human cell lines and in medicine has been reported recently (Sabbioni et al., 1989).In some higher fungi, accumulation of V paralleled that of Se (Byrne and Ravnik, 1976). Mizuno et al. (1988), Tong andKhoong (1994), andFu (1996) have reported germanium traces in Ganoderma lucidum (W. Curt.: Fr.) Karst. fruitbodies grown under normal conditions on various substrates in Japan, Taiwan, and Malaysia. They attempted Ge-bioenrichment in mycelial fermentations and fruiting cultivations of G. lucidum on large scales in order * Nuclear Research Institute, No. 1 Nguyen Tu Luc St., Dalat, Vietnam. ** To whom correspondence should be addressed.to improve yields of compounds with biopharmacological activities in the products from this well-known medicinal fungus.In view of the biochemical importance of the toxic and beneficial actions of mineral elements in higher fungi, particularly medicinal mushrooms, we examined the responses of G. lucidum to about 30 elements that are commonly distributed in fruitbodies. Of these, V, Se and Ge were found only in trace levels in G. lucidum commonly cultivated in Dalat, Vietnam (Tham, 1996a, b). To elucidate further the physiological responses of G. lucidurn to bioactive elements, particularly their bioaccumulation, in order to improve the pharmacological qualities of the mushroom, we investigated the growth of mycelia and fruitbody formation of G. lucidum varieties on media supplemented with V, Se and Ge.
Materials and MethodsThe newly found strains of G. lucidum in Dalat, Central Highlands of Vietnam (about 1,500 m above ...
