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|Title:||Phytochemical Investigations of Fungi: Hydrogen-Cyanide, Indole Alkaloids and Carbohydrates|
|Author(s):||Saupe, Stephen Gregory|
|Department / Program:||Plant Biology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The biology and chemistry of fungal secondary metabolites including hydrogen cyanide, indole alkaloids and reserve carbohydrates were investigated. The major emphasis of this study concerned the taxonomic significance and the mechanism of HCN production by microorganisms, especially fungi.
More than 250 species of fungi, primarily Basidiomycetes, were screened for cyanogenesis. Approximately 5% of these produced and accumulated detectable quantities of HCN. With few exceptions, cyanogenesis is restricted to members of the Agaricales and Aphyllophorales. Several literature reports of cyanogenic fungi are probably due to contamination of test materials with cyanogenic bacteria.
Cyanogenic compounds extracted from mycelial cultures and basidiocarps of several agarics have properties identical to those of cyanohydrins, and are a minor source of the cyanide recovered from Maramsius oreades. This fungus synthesizes and liberates HCN from a precursor without the intermediate formation of cyanogenic compounds. Glycine was the most effective amino acid precursor to HCN.
HCN production by basidiocarps of M. oreades was greatest at 23 C. Air was required for maximum synthesis of HCN, although low levels could be detected in a nitrogen environment. Cyanogenesis also was sensitive to buffer composition and had a pH optimum of 9.2. Mercuric chloride strongly inhibited the liberation of HCN.
Pseudomonas chlororaphis, a cyanogenic bacterium, also was studied to provide a more thorough understanding of fungal cyanogenesis. Cyanogenesis primarily occurred during the transition from the logarithmic to the stationary phase of growth and was stimulated by glycine. Glyoxylate was nearly as effective as glycine in enhancing cyanogenesis. An alkaline-labile cyanogenic compound(s) accumulated in the medium of P. chlororaphis cultures. The formation of this compound was enhanced by the addition of glyoxylate and was shown to be derived from the non-enzymatic condensation of HCN and a free carbonyl compound. It is suggested that this is the mechanism of cyanogenic compound formation in most fungi.
In addition to the above studies, it was shown that basidiocarps of Pluteus salicinus (Pluteaceae) contain the psychoactive, indole alkaloids psilocybin and psilocin, and large quantities of trehalose were isolated from M. oreades basidiocarps. A checklist of Basidiomycetes in Brownfield Woods, Urbana, Illinois also was prepared.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1981.
|Date Available in IDEALS:||2014-12-16|