Biol. Pharm. Bull. 29(6) 1191—1196 (2006)

Poria cocos WOLF), belonging to the Polyporaceae in basidiomycetes, forms sclerotia on the roots of such trees as pine, cedar, fir and oak. The major host plant of this fungus in Japan, China and Korea is the pine and the dried sclerotium of W. cocos is called “Bukuryo” in Japanese. In the Japanese Pharmacopoeia, the external layer is usually mostly removed. It is one of the most important crude drugs and is used in many Kampo formulae, for example, keishibukuryogan, goshajinkigan, goreisan and saireito. Recently, it has been reported that the triterpenoids of sclerotia have anti-inflammatory and anti-tumor promotion effects, anti-emetic activity and an efferent activity of the gastric vagus nerve. In Japan, there are few reports on the cultivation and biological studies of W. cocos. In the field, cultivation has obtained about 1 kg of sclerotium, which was unfortunately contaminated with a large amount of soil, and obtained only a small amount of sclerotium, about 25 g, by dry weight. In the laboratory, the formation of the fruit body has been obtained on agar or liquid media and sawdust media. However, there have been no studies as to the indoor cultivation and biological characteristics necessary for the formation of sclerotia. In the studies on cultivation with pine logs, we have shown cultivation in the field. The strain formed large sclerotia that were not contaminated with soil. The chemical qualities of the cultivated sclerotia were almost the same as those from commercial sources. On the other hand, we attempted a culture method of sclerotia using closed plastic bottles without soil in the laboratory. Generally, soil has been considered necessary to cultivate W. cocos sclerotia, but the formation of sclerotia was recognized in the bottles as well as in the cultivation in the field. The optimum temperature for sclerotia growth was 25 °C. The results suggested that this culture method may be used for the efficient production of sclerotia. Here, in order to establish a suitable method of indoor cultivation for production, we report on the improved culture method using mushroom culture bottles and some cultural characteristics of sclerotia in the laboratory. It was reported that a proper amount of moisture and supply of oxygen appeared to be important for the growth of sclerotia for cultivation in the field. Therefore, in this report, to determine the optimum conditions for sclerotia growth, three different air filtered and closed bottles were tested. Next, to clarify the cultural characteristics, the growth of sclerotia, the wood compositions and the contents of pachymic acid and dehydropachymic acid were measured. Additionally, the contents of these compounds and the TLC pattern of the cultivated samples were compared with those of the commercial samples.