Search

The bioaccumulation of artificial Cs-137 and natural radionuclides Th-234, Ra-226, and K-40 by Basidiomycetes of several species is studied and evaluated in relation to their substratum soils. For this reason, 32 fungal samples, representing 30 species of Basidiomycetes, were collected along with their substratum soil samples, from six selected sampling areas in Greece. The fungal fruit bodies and the soil samples were properly treated and the activity concentrations of the studied radionuclides were measured by gamma spectroscopy. The measured radioactivity levels ranged as follows: Cs-137 from <0.1 to 87.2 ± 0.4 Bq kg fresh weight (F.W.), Th-234 from <0.5 ± 0.9 to 28.3 ± 25.5 Bq kg F.W., Ra-226 from <0.3 to 1.0 ± 0.5 Bq kg F.W., and K-40 from 56.4 ± 3.0 to 759.0 ± 28.3 Bq kg F.W. The analysis of the results supported that the bioaccumulation of the studied natural radionuclides and Cs-137 is dependent on the species and the functional group of the fungi. Fungi were found to accumulate Th-234 and not U-238. What is more, potential bioindicators for each radionuclide among the 32 species studied could be suggested for each habitat, based on their estimated concentration ratios (CRs). The calculation of the CRs' mean values for each radionuclide revealed a rank in decreasing order for all the species studied. [ABSTRACT FROM AUTHOR]

Aspergillus species originating from Greece were examined by morphological and molecular criteria to explore the diversity of this genus. The phylogenetic relationships of these species were determined using sequences from the ITS and IGS region of the nuclear rRNA gene complex, two nuclear genes (β-tubulin (benA) and RNA polymerase II second largest subunit (rpb2)) and two mitochondrial genes (small rRNA subunit (rns) and cytochrome oxidase subunit I (cox1)) and, where available, related sequences from databases. The morphological characters of the anamorphs and teleomorphs, and the single gene phylogenetic trees, differentiated and placed the species examined in the well-supported sections of Aenei, Aspergillus, Bispori, Candidi, Circumdati, Clavati, Cremei, Flavi, Flavipedes, Fumigati, Nidulantes, Nigri, Restricti, Terrei, Usti, and Zonati, with few uncertainties. The combined use of the three commonly employed nuclear genes (benA, rpb2, and ITS), the IGS region, and two less often used mitochondrial gene sequences (rns and cox1) as a single unit resolved several taxonomic ambiguities. A phylogenetic tree was inferred using Neighbour-Joining, Maximum Parsimony, and Bayesian methods. The strains examined formed seven wellsupported clades within the genus Aspergillus. Altogether, the concatenated nuclear and mitochondrial sequences offer additional tools for an improved understanding of phylogenetic relationships within this genus. [ABSTRACT FROM AUTHOR]

Malassezia furfur was the first species described within the cosmopolitan yeast genus Malassezia, which now comprises 13 species. Reported isolation rates of these species from healthy and diseased human skin show geographic variations. PCR-fingerprinting with the wild-type phage M13 primer (5′-GAGGGTGGCGGTTCT-3′) was applied to investigate phylogeographic associations of M. furfur strains isolated from Scandinavians residing permanently in Greece, in comparison to clinical isolates from Greek, Bulgarian and Chinese native residents. Seven M. furfur strains from Scandinavians were compared with the Neotype strain (CBS1878), CBS global collection strains (n=10) and clinical isolates from Greece (n=4), Bulgaria (n=15) and China (n=6). Scandinavian, Greek and Bulgarian M. furfur strains mostly formed distinct group clusters, providing initial evidence for an association with the host's geographical origin and with the underlying skin condition. These initial data address the hypothesis that M. furfur could be a eukaryotic candidate eligible for phylogeographic studies.The ISME Journal (2009) 3, 498–502; doi:10.1038/ismej.2008.112; published online 20 November 2008 [ABSTRACT FROM AUTHOR]

Aflatoxin B1 (AFB1) represents one of the most important food toxicants. The most important aflatoxin producers are Aspergillus flavus and A. parasiticus. Strains identified as Aspergillus section Nigri were isolated from dried vine fruits originating from Corinthos (1 strain) and Crete (3 strains). In this study, the effect of Aspergillus section Nigri strains on growth and AFB1 production by A. parasiticus was investigated during 18 days of incubation in liquid Yeast Extract Sucrose medium. It was found, that Aspergillus section Nigri strains produced AFB1, even at low levels. On the 12th day of incubation, which was the day of AFB1 maximum production for the four strains, the AFB1 levels were 98.3 - 99.9% less than those recorded for Aspergillus parasiticus, on the same day. The AFB1 production by the strain of A. parasiticus on the 12th day of incubation was reduced by 97.5% when co-cultured with the strain of Aspergillus section Nigri from Corinthian dried vine fruit, whereas it was reduced by 99.9% when co-cultured with the three strains from Cretan dried vine fruits. These findings indicate that the presence of Aspergillus section Nigri strains may inhibit almost completely the AFB1 production by A. parasiticus. [ABSTRACT FROM AUTHOR]

Abstract: Aflatoxin B1 (AFB1) mostly produced by Aspergillus flavus and Aspergillus parasiticus, is an extremely toxic and carcinogenic metabolite. Currants are used in the Mediterranean diet as a food with antioxidant properties. Four strains of Aspergillus section Nigri have been isolated from currants originated from Crete and Corinth. In this study AFB1 production by A. parasiticus and the four strains of Aspergillus section Nigri in Cretan and Corinthian currants (Vitis vinifera L.) is investigated. AFB1 determination was performed by HPLC–FID. Results revealed that the four strains Aspergillus section Nigri, as well as the aflatoxigenic strain A. parasiticus produced AFB1 (0.0052–1.31 μg AFB1 15 g−1, corresponding to 0.0003–0.087 μg AFB1 g−1) in both type of currants (Cretan and Corinthian) on the 12th day of observation. Moreover, AFB1 production, by A. parasiticus in the synthetic Yeast Extract Sucrose (YES) medium was also studied. The ability of AFB1 production has been affected by the special characteristics of each isolate and the currants substrate. [Copyright &y& Elsevier]