Polyporus umbellatus (Syn. Grifola umbellata) is a sclerotium forming mushroom belongs to family Poly-poraceae of Polyphorales, Basidiomycota. The sclerotia of P. umbellatus have long been used for traditional medicinesin China, Korea and Japan. This study was initiated to obtain the basic data for artificial sclerotial production of P. umbel-latus. Here, we investigated the favorable conditions for mycelial growth of P. umbellatus and its symbiotic fungus Armill-aria mellea. We also evaluate the favorable carbon and nitrogen sources for sclerotial formation in dual culture betweenP. umbellatus and A. mellea. The favorable conditions for mycelial growth of P. umbellatus were 20°C and pH 4, whileoptimal conditions for mycelial growth of A. mellea were 25°C and pH 6. The carbon sources for optimal mycelial growthof P. umbellatus were fructose and glucose, while carbon sources for favorable mycelial growth of A. mellea were alsofructose and glucose. The nitrogen sources for favorable mycelial growth P. umbellatus were peptone and yeast extract,while optimal mycelial growth of A. mellea were obtained in peptone and yeast extract. When P. umbellatus and A. melleawere dual cultured on carbon sources, sclerotia were induced on basal media supplemented with glucose, fructose andmaltose at pH 4~6, while nitrogen sources inducing sclerotia were basal media supplemented with peptone and yeastextract for 60 days at 20°C under dark condition.

보존중인 Polyporus속 균주를 선발하여 배양 및 형태적 특성을 조사하여 비슷한 균주별로 그룹화하여 rDNA의 ITS 영역을 증폭하여 염기서열을 결정한 결과 보존시 균주의 학명과 많은 차이를 보였으며, 균사의 모양 및 색깔에도 많은 차이를 보였다. 보존 당시 동정한 결과와 rDNA의 ITS 영역의 염기서열 분석을 통한 결과를 비교한 결과 종이 다른 균주가 3균주와 학명이 다른 균주가 4균주로 전체의 53.8%를 차지하였다. 국내에서 수집한 Polyporus속은 경우 P. alveolarius, P. brumalis, P. squamosus, P. tuberaster, P. arcularius 등 5개 종으로 동정되었고, 미국에서 수집한 균주는 P. alveolarius와 P. arcularius로 동정되었다. 그리고 일본에서 수집한 균주는 P. arcularius로 동정되었다. RAPD분석을 통한 유전적인 다형성 조사에서 Polyporus속간에는 완전히 다른 밴드 패턴을 보였지만 같은 종내에서는 비슷한 밴드 패턴을 보였다. 유전적인 유연관계 분석에서는 P. alveolarius 등 5개의 분류군으로 나누어졌으며, ITS부위 유전자수준의 상동성 분석에서도 비슷한 경향을 보였다. 따라서 기존 목록과 완전히 다른 속으로 동정된 균주들에 대해서는 계통분류학적인 유연관계 분석과 보존중인 자실체 유전자와의 상동성을 비교하여 기존 목록의 학명을 재분류해야 할 것으로 판단된다.

The genes encoding cellulases, which belong to glycosyl hydrolase families have been cloned from the basidiomycetous mushrooms. The transcripts of cellulase genes are strongly induced when the mycelia are grown in medium containing crystalline cellulose, and they are not expressed in medium containing glucose, but how insoluble substrates such as microcrystalline cellulose are recognized by these fungal cells is not clear. The polypore mushroom Polyporus arcularius is a wood-decomposing basidiomycete that produces at least three types (I, II, and IIIa) of carboxymethyl cellulase (CMCase) when the medium contains crystalline cellulose as the sole carbon source and produced mainly cellobiose in the medium. The genomic and cDNA clones encoding the family 12 endoglucanase (CMCase IIIa) gene (cel3A) of P. arcularius have been sequenced, and Cel3A has been expressed as an active enzyme in Escherichia coli. To determine the role and function of each type of cellulase in the degradation of crystalline cellulose by basidiomycetous mushrooms, the structure of all of the cellulase genes should be investigated, but the nucleotide sequences of the other cellulase genes in P. arcularius have not yet been reported. In the current study, the genomic and cDNA clones encoding the endoglucanases (cel4), and the two cellobiohydrolases (cel1 and cel2) of P. arcularius sequenced and characterized. The predicted amino acid sequence of Cel1 Cel2, Cel3a and Cel4 are similar to glycosyl hydrolase family 7, 6 12 and 5 protein, respectively. The expressions of the all cellulase genes (cel1 cel2, cel3a and cel4) were induced by Avicel (microcrystalline cellulose) and cellopentaose but repressed by glucose, cellobiose, cellotriose, and cellotetraose. There was a low level of transcription of both genes regardless of the carbon source. These results suggest that P. arcularius cells constitutively express a very low level of cellulase that can degrade insoluble crystalline cellulose and that the transcription of celluases in the cells is induced by products produced by these endoglucanases such as cellooligosaccharides. From our findings, we propose a possible mechanism for the recognition and degradation of insoluble crystalline cellulose by fungal cells.