The yeast flora of some decaying mushrooms on trunks of living trees

Abstract

ABSTRACT. Several ascomycetous and basidiomycetous yeasts were isolated from rotten mushrooms on the trunks of beech and tamarisk trees. One strain, identified as the novel species Cryptococcus allantoinivorans, assimilated allantoin as the sole carbon source. Phylogenetically it belongs to the C. laurentii complex, Papiliotrema bandonii being the closest relative. Some ascomycetous strains could not be distinguished from Pichia guillermondii, but deviated considerably in rDNA sequences. In addition to these species, both decaying mushrooms were inhabited by more common species, viz. Candida albicans, C. saitoana, Rhodotorula mucilaginosa, Trichosporon asahii, T. multisporum and T. porosum. The basidiomycetous yeasts, except R. mucilaginosa, assimilated some polysaccharides of plant origin.Several yeast species assimilate a great variety of carbon sources in addition to those used for yeast identification and taxonomy (Middelhoven et al. 1985(Middelhoven et al. , 1991(Middelhoven et al. , 2001(Middelhoven et al. , 2004aMiddelhoven and Kurtzman 2003). Uric acid is one of these nonconventional substrates (Middelhoven et al. 1983). Like other aerobic microorganisms, ascomycetous and a basidiomycetous yeast species degrade uric acid by oxidation to allantoin that, in three successive hydrolytic steps, is converted into 1 mol glyoxylate and 2 mol urea (Middelhoven et al. 1983). Surprisingly, most yeast species assimilating uric acid as the sole carbon source failed to grow at the expense of allantoin, in spite of equal energetic value. Middelhoven et al. (1985) demonstrated that of 14 ascomycetous and basidiomycetous yeast species, growing on uric acid as the sole carbon source, only Stephanoascus ciferrii M.TH. SMITH et al. assimilated allantoin. It is wide-spread in nature and is a source of nitrogen for many yeast species. Nevertheless, several attempts to isolate yeasts from soil by enrichment culture on allantoin as the sole carbon source failed. In the present study such yeasts were looked for in another habitat, viz. decaying mushrooms. It has been known for a long time that mushrooms contain allantoin (Brunel 1931(Brunel , 1936. Mushrooms also contain chitin as a constituent of the fungal cell wall. Assimilation of this polysaccharide by yeasts has never been reported. Attempts were made to isolate such yeasts from decaying mushrooms.The present study was not restricted to isolation of yeasts with characteristic biochemical abilities. In addition, several yeast species present in decaying mushrooms were identified as representatives of wellknown species. However, some very rare species and some strains physiologically similar to Pichia guillermondii but belonging to undescribed species were also isolated. The basidiomycetous yeasts were tested for growth on several polysaccharides of plant origin. MATERIALS AND METHODSIsolation of the strains. The rotting mushrooms sampled were Hericium erinaceus (BULL.:FR.)PERS. on the trunk of a beech tree (Fagus sylvatica L.) in Wageningen (The Netherlands) September 2000,...

Four new Candida cretensis strains isolated from Spanish fermented sausages (chorizo): Taxonomic and phylogenetic implications

“…Sequence analysis showed that the strains exhibit identical D1/D2 26S rRNA gene domains and similar 5.8S-ITS regions to a yeast strain isolated from a decaying mushroom (Middelhoven, 2004), which was recently described as C. cretensis (Middelhoven & Kurtzman, 2007). This high similarity was also confirmed by sequence analysis of the actin gene, indicating that they belong to the same yeast species.…”

Four novel yeasts from decaying organic matter: Blastobotrys robertii sp. nov., Candida cretensis sp. nov., Candida scorzettiae sp. nov. and Candida vadensis sp. nov.

“…Maire growing on a Tamarix tree near the sea side in Plakias, Crete, Greece in October 2000 (Middelhoven 2004). The type strain is preserved as a lyophilized preparation in two culture collections, viz.…”

“…: Fr.) Pers., growing on a beech tree, Fagus sylvatica L., in Wageningen, The Netherlands, in September 2000 (Middelhoven 2004). The type strain was deposited in two culture collections, viz.…”

“…Recently, two studies have been undertaken. Middelhoven (2004Middelhoven ( , 2006 analysed the yeast flora of two decaying mushrooms as well as that of several samples of rotten wood. In addition to known species, both studies yielded two anamorphic ascomycetous species that could not be identified.…”

Colonization Survey of Cryptococcus neoformans in Tamarix Tree (Genus: Tamarix L.) in South-Western Anatolia, Turkey

“…Araştırmaya konu olan ılgın ağaçlarında, türler arasında farklılıklar olmakla birlikte, flavonoidlerin, fenolik yapılı bileşiklerin, kumarinlerin, taninlerin ve serbest alkollerin yoğun bulunabildiği rapor edilmiştir (13) . Farklı yapıla-rında antiseptik özelliği bulunmasına karşılık, bazı basidiyomiçet ve askomiçet mantarlar ılgın ağaçlarında çoğalabilmektedir (26) .…”