Fast atom bombardment (FAB) mass spectrometry enables the analyses in positive and negative ion modes, providing different information. Therefore, the method is a powerful tool for analyzing the structure of polyisoprenepolyols. Although some of the structural information is available from routine FAB mass spectra, the linked scan spectra provides information in more detail. In this paper, we briefly review our recent works and describe the structural elucidation of a precursory substance of bitterness, polyisoprenepolyols isolated from a edible mushroom (Hypsizygus mannoreus) by FAB mass spectrometry.

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The differences in nutritional requirements for the formation of atypical fruiting structures (AFS) and fruit body primordia (FBP) in Ganoderma lucidum were examined. Various carbohydrates including mono-, di- and polysaccharides and sugar alcohols supported the mycelial growth. The allowance of carbon source concentrations for mycelial growth of Gl-009 and Gl-010 isolates from G. lucidum were 0.5-4.0 and 0.5-6.0%, respectively. Furthermore, Gl-009 produced FBP on media containing various carbon sources, but Gl-010 could not produce FBP with any carbon sources. On the other hand, this fungus may require severe carbon source condition for AFS formation; Gl-010 needed two selected carbohydrates, arabinose and sucrose for AFS formation, but Gl-009 did not form this structure with any carbon source. Glucose and sucrose concentrations over 4% and 2%, respectively, suppressed AFS formation. G. lucidum grew on the media containing various inorganic and organic nitrogen sources, although the mycelial growth index (MGI) scores for inorganic nitrogen were lower than those with organic single compounds or complex nitrogen sources. AFS formation in Gl-009 and FBP formation in Gl-010 Yeast occurred on media in which either tryptone or yeast extract was used as a replacement for peptone.

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Hiratake mushroom (Pleurotus ostreatus) was cultivated on a sawdust medium with supplements (rice bran, wheat bran, soybean curd residue, corn bran or brewer's grains). As the result, the fruiting did not occur on the sawdust brewer's grains medium. In the case of this supplement, the potassium content of brewer's grains was extremelly lower than those of other supplements. The fruit-bodies appeared on the sawdust brewer's grains medium added KCl. The yield of fruit-bodies differed according to amount of addition of KCl on brewer's grains medium. These results suggested that the potassium content of medium is important on the fruit-body formation and the yield of fruit-bodies.

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Invasion of Shiitake bed logs by Armillaria spp. was investigated in Uryu Experimental Forest of Hokkaido University. About 50% of the bed logs were invaded by rhizomorphs of Armillaria spp. The percentages of invasion in blocks are from 4.1 to 93.0, but showed the difference according to the blocks of the bed logs. It is considered that the bed logs were directly invaded by rhizomorphs of Armillaria spp. living in soil.

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