Insights into the mechanism of cyanobacteria removal by the algicidal fungi Bjerkandera adusta and Trametes versicolor.

Fungal mycelia can eliminate almost all cocultured cyanobacterial cells within a short time. However, molecular mechanisms of algicidal fungi are poorly understood. In this study, a time-course transcriptomic analysis of algicidal fungus Bjerkandera adusta T1 was applied to investigate gene expression and regulation. A total of 132, 300, 422, and 823 differentially expressed genes (DEGs) were identified at 6, 12, 24, and 48 hr, respectively. Most DEGs exhibited high endopeptidase activity, cellulose catabolic process, and transmembrane transporter activity by using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Many decomposition genes encoding endopeptidases were induced a little later in B. adusta T1 when compared with previously investigated algicidal fungus Trametes versicolor F21a. Besides, the accumulated expression of Polysaccharide lyases8 (PL8) gene with peptidoglycan and alginate decomposition abilities was greatly delayed in B. adusta T1 relative to T. versicolor F21a. It was implied that endopeptidases and enzymes of PL8 might be responsible for the strong algicidal ability of B. adusta T1 as well as T. versicolor F21a.

A Wild Fomes fomentarius for Biomediation of One Pot Synthesis of Titanium Oxide and Silver Nanoparticles for Antibacterial and Anticancer Application.

The present study offers an alternative method for green synthesis of the formation of two types of nanoparticles (NPs). These NPs, titanium oxide and silver NPs (TiO2 and Ag NPs, respectively), were obtained from the amalgamation of intracellular extract of a wild mushroom, Fomes fomentarius, with aqueous solutions of titanium isopropoxide and silver nitrate, respectively. F. fomentarius was identified phenotypically and by 18S ribosomal RNA gene sequencing (Gene accession no: MK635351). The biosynthesis of TiO2 and Ag NPs was studied and characterized by X-ray diffraction (XRD), diffuse reflectance UV-Visible spectroscopy (DR-UV), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscope (TEM). Success was achieved in obtaining NPs of differing sizes and shapes. The antibacterial and anticancer activity of the NPs was significant with morphological damage being caused by both, although Ag NPs (10-20 nm) were found to have profound effects on bacterial and cancer cells in comparison to TiO2 NPs (100-120 nm). These metal NPs, synthesized using wild mushrooms, hold a great potential in biomedicinedue to an effective enzyme combination, which permits them to modify different chemical compounds to less toxic forms, which is required for ecofriendly and safe biomaterials.

Fomitopsis mounceae and F. schrenkii-two new species from North America in the F. pinicola complex.

Two new species, Fomitopsis mounceae and F. schrenkii (Polyporales, Basidiomycota) in the F. pinicola species complex in North America, are described and illustrated. Previous molecular phylogenetic analyses identified three well-delimited lineages that represent F. mounceae and F. ochracea from Canada, the Appalachian Mountains, and the northern United States and F. schrenkii from western and southwestern regions of the United States. Fomitopsis pinicola sensu stricto is restricted to Eurasia and does not occur in North America. Morphological descriptions of basidiocarps and cultures for F. mounceae, F. schrenkii, and F. ochracea are presented. The three species are readily differentiated by nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) sequence, geographic distribution, and basidiospore size. Polyporus ponderosus H. Schrenk is an earlier illegitimate synonym of F. schrenkii. Both F. mounceae and F. schrenkii have a heterothallic multiallelic incompatibility system.

Chemical composition and biological activity of extracts from fruiting bodies and mycelial cultures of Fomitopsis betulina.

Fomitopsis betulina (Bull.) B.K. Cui, M.L. Han & Y.C. Dai has been used for medicinal purposes for over 5000 years. Numerous studies have confirmed the biological activity of compounds found in this species. The purpose of this study was a comparative analysis of selected groups of metabolites in the extracts from fruiting bodies and mycelial cultures. Phenolic acids (syringic, gallic, p-hydroxybenzoic, 3,4-dihydrophenylacetic), indole compounds (L-tryptophan, 5-hydroxy-L-tryptophan, 5-methyltryptamine), sterols (ergosterol, ergosterol peroxide, hexestrol, cholecalciferol), and triterpenes (betulinic acid, betulin) were determined quantitatively by high performance liquid chromatography with UV-Vis/DAD detection, while fatty acids were assessed with the gas chromatography method. Cytotoxic activity against selected human cancer cell lines was determined using the lactate dehydrogenase test. Anti-inflammatory activity was evaluated on lipopolysaccharide activated A549 cells. Those extracts with anti-inflammatory activity were evaluated for their inhibition of pro-inflammatory enzymes. The mycelium extract exhibited significant cytotoxic activity against prostate cancer cells, while the fruiting body extract indicated a moderate effect on the viability of melanoma and prostate cancer. Incubation of lung epithelial cells with biomass extract significantly decreased cyclooxygenase-2 levels compared to LPS activated A549 cells. This paper is the first report of a comparative quantitative analysis of the metabolites in mycelial cultures and fruiting bodies. In addition, a novel element of this study is its comparison of the cytotoxic and anti-inflammatory activity of the obtained extracts. The results of comparing the composition and activity of mycelium and fruiting bodies shows that the cultures could be proposed as a potential biotechnological source for selected biologically active compounds.

Genetic Variability of the Medicinal Tinder Bracket Polypore, Fomes fomentarius (Agaricomycetes), from the Asian Part of Russia.

We analyzed intraspecies genetic variability of the medicinal tinder bracket polypore, Fomes fomentarius, from the Asian part of Russia, including the Ural, Altai, Western Sayan, and Baikal regions. We used nuclear ribosomal DNA internal transcribed spacer (ITS) sequence data as a standard marker for fungal DNA barcoding. In the Asian part of Russia, lineage A occurs as sublineage A2, which differs from sublineage A1 by a single nucleotide insertion at ITS2.3. Sublineage A2 is distributed up to Lake Baikal in the Ural, Altai, and Western Sayan regions. It can be characterized as a Eurasian sublineage of F. fomentarius. Lineage B is also represented by 2 sublineages (B1 and B2), which differ from each other by nucleotide sequences at ITS2.1. Sublineage B1 is represented by a small group of isolates from Asia (Iran, China, Nepal, South Korea), whereas sublineage B2 mainly includes isolates from Europe (Great Britain, Italy, Latvia, Slovakia, Slovenia) and 2 separate samples from Asia (Iran, China); these locales compose the distribution area of F. fomentarius. In the Asian part of Russia, lineage B is represented by sublineage B2 found in the Southern Urals (at the border between Europe and Asia), which is the only area where sublineages A2 and B2 are present. These sublineages are characterized by different substrate spectra: sublineage A2 is predominantly associated with Betula spp. and rarely with Alnus and Larix trees, whereas sublineage B2 does not have a pronounced substrate preference and is found in basidiomes collected from Acer, Duschekia, Prunus, and Salix trees, but not Betula trees. In general, the spectrum of substrates for F. fomentarius lineages A and B in the Asian part of Russia corresponds to that in other parts of this polypore's distribution area. Data are needed on genetic intraspecies variability (polymorphism) in relation to pharmacological properties for further biotechnological cultivation and use of the medicinal fungus F. fomentarius.

Substrate-Specific Differential Gene Expression and RNA Editing in the Brown Rot Fungus Fomitopsis pinicola.

Wood-decaying fungi tend to have characteristic substrate ranges that partly define their ecological niche. Fomitopsis pinicola is a brown rot species of Polyporales that is reported on 82 species of softwoods and 42 species of hardwoods. We analyzed the gene expression levels and RNA editing profiles of F. pinicola from submerged cultures with ground wood powder (sampled at 5 days) or solid wood wafers (sampled at 10 and 30 days), using aspen, pine, and spruce substrates (aspen was used only in submerged cultures). Fomitopsis pinicola expressed similar sets of wood-degrading enzymes typical of brown rot fungi across all culture conditions and time points. Nevertheless, differential gene expression and RNA editing were observed across all pairwise comparisons of substrates and time points. Genes exhibiting differential expression and RNA editing encode diverse enzymes with known or potential function in brown rot decay, including laccase, benzoquinone reductase, aryl alcohol oxidase, cytochrome P450s, and various glycoside hydrolases. There was no overlap between differentially expressed and differentially edited genes, suggesting that these may provide F. pinicola with independent mechanisms for responding to different conditions. Comparing transcriptomes from submerged cultures and wood wafers, we found that culture conditions had a greater impact on global expression profiles than substrate wood species. In contrast, the suites of genes subject to RNA editing were much less affected by culture conditions. These findings highlight the need for standardization of culture conditions in studies of gene expression in wood-decaying fungi.IMPORTANCE All species of wood-decaying fungi occur on a characteristic range of substrates (host plants), which may be broad or narrow. Understanding the mechanisms that enable fungi to grow on particular substrates is important for both fungal ecology and applied uses of different feedstocks in industrial processes. We grew the wood-decaying polypore Fomitopsis pinicola on three different wood species, aspen, pine, and spruce, under various culture conditions. We examined both gene expression (transcription levels) and RNA editing (posttranscriptional modification of RNA, which can potentially yield different proteins from the same gene). We found that F. pinicola is able to modify both gene expression and RNA editing profiles across different substrate species and culture conditions. Many of the genes involved encode enzymes with known or predicted functions in wood decay. This work provides clues to how wood-decaying fungi may adjust their arsenal of decay enzymes to accommodate different host substrates.

Overview of the Biological Activities of a Methanol Extract from Wild Red Belt Conk, Fomitopsis pinicola (Agaricomycetes), Fruiting Bodies from Central Italy.

Fomitopsis pinicola (Sw.) P. Karst. (Fomitopsidaceae) is a medicinal mushroom with a variety of healthy properties. In this study we tested the radical scavenging activity and antimicrobial and anticancer potential of methanol extracts of F. pinicola from central Italy. Molecular identification confirmed that the samples were F. pinicola; a Basic Local Alignment Search Tool search showed a close match (99% sequence identity) with European isolates of this species. The free radical scavenging capacities, measured by DPPH assay, showed that the extract activity was 3.5% that of Trolox. The MTT test, evaluated after 72 hours of treatment with increasing doses of extract (5-500 µg · mL-1), considerably inhibited proliferation in a dose-dependent manner in 2 human tumor cell lines. This reduction was coupled with a relevant induction of apoptosis in the human leukemia THP-1 cell line after 24 hours of treatment, but a relevant toxic effect occurred in the human colon adenocarcinoma HT29 cell line. The genotoxic potential of the methanol extracts was studied by single-cell gel electrophoresis of normal human leukocytes exposed to 20 µg extract at 37°C for 30 minutes; no DNA damage was observed. The F. pinicola methanol extract was found to have varying degrees of antifungal effects against the pathogenic fungi tested (minimum inhibitory concentration from 23.63 to 66.81 µg · mL-1). The results show that the tested F. pinicola extract has strong antimicrobial and chemo-preventive activities, but is a poor antioxidant.

Medicinal Value and Taxonomy of the Tinder Polypore, Fomes fomentarius (Agaricomycetes): A Review.

The tinder polypore, Fomes fomentarius, is a wood-decaying macrofungus well known for its potential use in a wide range of biotechnological applications. The existence of 3 distinct internal transcribed spacer lineages/sublineages among its strains has been clearly established. Sublineage A1 consists of strains isolated from North America, whereas sublineage A2 consists of strains only from Europe. Lineage B comprises strains from Europe and Asia. A better understanding of the biological features of F. fomentarius lineages/sublineages could lead to improved characterization, leading to better biotechnological applications. The medicinal value of F. fomentarius is discussed.

Phylogeny of Fomitopsis pinicola: a species complex.

Fungal species with a broad distribution may exhibit considerable genetic variation over their geographic ranges. Variation may develop among populations based on geographic isolation, lack of migration, and genetic drift, though this genetic variation may not always be evident when examining phenotypic characters. Fomitopsis pinicola is an abundant saprotrophic fungus found on decaying logs throughout temperate regions of the Northern Hemisphere. Phylogenetic studies have addressed the relationship of F. pinicola to other wood-rotting fungi, but pan-continental variation within F. pinicola has not been addressed using molecular data. While forms found growing on hardwood and softwood hosts exhibit variation in habit and appearance, it is unknown if these forms are genetically distinct. In this study, we generated DNA sequences of the nuc rDNA internal transcribed spacers (ITS), the TEF1 gene encoding translation elongation factor 1-α, and the RPB2 gene encoding the second largest subunit of RNA polymerase II for collections across all major geographic regions where this fungus occurs, with a primary focus on North America. We used Bayesian and maximum likelihood analyses and evaluated the gene trees within the species tree using coalescent methods to elucidate evolutionarily independent lineages. We find that F. pinicola sensu lato encompasses four well-supported, congruent clades: a European clade, southwestern US clade, and two sympatric northern North American clades. Each clade represents distinct species according to phylogenetic and population-genetic species concepts. Morphological data currently available for F. pinicola do not delimit these species, and three of the species are not specific to either hardwood or softwood trees. Originally described from Europe, F. pinicola appears to be restricted to Eurasia. Based on DNA data obtained from an isotype, one well-defined and widespread clade found only in North America represents the recently described Fomitopsis ochracea The remaining two North American clades represent previously undescribed species.

Diversity of Polypore Bracket Mushrooms, Polyporales (Agaricomycetes), Recorded in Armenia and Their Medicinal Properties.

The list of polypore bracket mushrooms (Polyporales) recorded in Armenia is presented. The order Polyporales in Armenia is currently represented by 87 species (4 varieties) belonging to 47 genera. Information regarding the study of the medicinal properties (e.g., antifungal, antibacterial, mitogenic, regenerative, antioxidant, proteolytic) of genetically identified mycelial collections of several polypore species-mainly from the genera Daedalea, Fomes, Fomitopsis, Ganoderma, Laetiporus, Piptoporus, Polyporus, and Trametes-is reported, as well.

Morphological and molecular evidence for two new species of Laetiporus (Basidiomycota, Polyporales) from southwestern China.

Two Laetiporus species, L. ailaoshanensis and L. zonatus spp. nov., are described from southwestern China based on morphological and molecular characters. Laetiporus ailaoshanensis is characterized by orange-yellow to reddish orange pileal surface and cream to buff pores when fresh, azonate to faintly zonate pileus, ovoid to ellipsoid basidiospores (5.0-6.2 × 4.0-5.0 µm), and it has been observed only on Lithocarpus. Laetiporus zonatus is characterized by white to cream pileal surface with buff to clay-buff base when fresh, concentrically zonate basidiocarps, ellipsoid to pyriform or drop-shaped basidiospores (5.8-7.2 × 4.3-5.5 µm), and it has been found only on Quercus. The phylogenetic relationships of all recognized Laetiporus species were inferred from a combined dataset of ITS and nLSU-rDNA sequences, and L. ailaoshanensis and L. zonatus represent two new lineages in this group.

De novo sequencing and transcriptome analysis of Wolfiporia cocos to reveal genes related to biosynthesis of triterpenoids.

Wolfiporia cocos Ryvarden et Gilbertson is a saprophytic fungus in the Basidiomycetes. Its dried sclerotium is widely used as a traditional crude drug in East Asia. Especially in China, the dried sclerotium is regarded as the silver of the Chinese traditional drugs, not only for its white color, but also its medicinal value. Furthermore, triterpenoids from W. cocos are the main active compounds with antitumor and anti-inflammatory activity. Biosynthesis of the triterpenoids has rarely been researched. In this study, the de novo sequencing of the mycelia and sclerotia of W. cocos were carried out by Illumina HiSeq 2000. A total of 3,484,996,740 bp from 38,722,186 sequence reads of mycelia, and 3,573,921,960 bp from 39,710,244 high quality sequence reads of sclerotium were obtained. These raw data were assembled into 60,354 contigs and 40,939 singletons, and 56,938 contigs and 37,220 singletons for mycelia and sclerotia, respectively. The transcriptomic data clearly showed that terpenoid biosynthesis was only via the MVA pathwayin W. cocos. The production of total triterpenoids and pachymic acid was examined in the dry mycelia and sclerotia. The content of total triterpenoids was 5.36% and 1.43% in mycelia and sclerotia, respectively, and the content of pachymic acid was 0.458% and 0.174%. Some genes involved in the triterpenoid biosynthetic pathway were chosen to be verified by qRT-PCR. The unigenes encoding diphosphomevalonate decarboxylase (Unigene 20430), farnesyl diphosphate synthase (Unigene 14106 and 21656), hydroxymethylglutaryl-CoA reductase (NADPH) (Unigene 6395_All) and lanosterol synthase (Unigene28001_All) were upregulated in the mycelia stage. It is likely that expression of these genes influences the biosynthesis of triterpenoids in the mycelia stage.

Genomewide annotation and comparative genomics of cytochrome P450 monooxygenases (P450s) in the polypore species Bjerkandera adusta, Ganoderma sp. and Phlebia brevispora.

Genomewide annotation of cytochrome P450 monooxygenases (P450s) in three white-rot species of the fungal order Polyporales, namely Bjerkandera adusta, Ganoderma sp. and Phlebia brevispora, revealed a large contingent of P450 genes (P450ome) in their genomes. A total of 199 P450 genes in B. adusta and 209 P450 genes each in Ganoderma sp. and P. brevispora were identified. These P450omes were classified into families and subfamilies as follows: B. adusta (39 families, 86 subfamilies), Ganoderma sp. (41 families, 105 subfamilies) and P. brevispora (42 families, 111 subfamilies). Of note, the B. adusta genome lacked the CYP505 family (P450foxy), a group of P450-CPR fusion proteins. The three polypore species revealed differential enrichment of individual P450 families in their genomes. The largest CYP families in the three genomes were CYP5144 (67 P450s), CYP5359 (46 P450s) and CYP5344 (43 P450s) in B. adusta, Ganoderma sp. and P. brevispora, respectively. Our analyses showed that tandem gene duplications led to expansions in certain P450 families. An estimated 33% (72 P450s), 28% (55 P450s) and 23% (49 P450s) of P450ome genes were duplicated in P. brevispora, B. adusta and Ganoderma sp., respectively. Family-wise comparative analysis revealed that 22 CYP families are common across the three Polypore species. Comparative P450ome analysis with Ganoderma lucidum revealed the presence of 143 orthologs and 56 paralogs in Ganoderma sp. Multiple P450s were found near the characteristic biosynthetic genes for secondary metabolites, namely polyketide synthase (PKS), non-ribosomal peptide synthetase (NRPS), terpene cyclase and terpene synthase in the three genomes, suggesting a likely role of these P450s in secondary metabolism in these Polyporales. Overall, the three species had a richer P450 diversity both in terms of the P450 genes and P450 subfamilies as compared to the model white-rot and brown-rot polypore species Phanerochaete chrysosporium and Postia placenta.

Phylogenetic and phenotypic characterization of Fomes fasciatus and Fomes fomentarius in the United States.

The wood-decay fungi Fomes fasciatus and F. fomentarius share many morphological characters that historically have made species delimitation challenging. We examined morphological, molecular and physiological characters of basidiomata and pure cultures of F. fasciatus and F. fomentarius sampled from multiple plant hosts and geographic regions in the United States to determine whether they support separation of the two species. We find that mean basidiospore size is significantly larger in F. fomentarius and represents the most informative morphological character for delineating the species. Basidiomata and pore-surface shape provided additional resolution of the species, but these characters often overlap and are more variable than basidiospore size. Phylogenetic analyses of ITS and RPB2 sequences suggest that F. fasciatus and F. fomentarius represent distinct evolutionary lineages. The two species share less than 88% maximum identity for the ITS region. Limited intraspecific sequence variation at each locus also was observed. In vitro experiments of hyphal-growth response to a wide range of temperatures support differences in physiology between the two species.

Taxonomy and phylogeny of the genus Megasporoporia and its related genera.

Taxonomic and phylogenetic studies on Megasporoporia s.l. were carried out. Phylogenetic analysis based on ITS and nLSU sequences showed that Megasporoporia s.l. belonging to the core polyporoid clade, however, it is not monophyletic, and four clades were recognized. The Megasporoporia s.s. clade includes M. setulosa and two new species, M. bannaensis and M. minor spp. nov. Two monophyletic clades were segregated from Megasporoporia s.l., and two new genera were established. Megasporia gen. nov. is composed of M. cystidiolophora, M. ellipsoidea, M. hexagonoides, M. major, M. violacea, and two new species, M. guangdongensis and M. hengduanensis spp. nov. Megasporoporiella gen. nov. including M. cavernulosa, M. rhododendri, M. subcavernulosa, and two new species, M. lacerata and M. pseudocavernulosa spp. nov. Megasporoporia quercina grouped with Grammothele fuligo in the Grammothele clade, so it is transferred to Grammothele and a new combination, G. quercina, is proposed. The main morphological characters of Megasporoporia and the two new genera are discussed, and identification keys to the three genera are provided.

Phylogenetic relationships in European Ceriporiopsis species inferred from nuclear and mitochondrial ribosomal DNA sequences.

The aim of this work was to clarify taxonomy and examine evolutionary relationships within European Ceriporiopsis species using a combined analysis of the large subunit (nLSU) nuclear rRNA and small subunit (mtSSU) mitochondrial rRNA gene sequences. Data from the ITS region were applied to enhance the view of the phylogenetic relationships among different species. The studied samples grouped into four complex clades, suggesting that the genus Ceriporiopsis is polyphyletic. The generic type Ceriporiopsis gilvescens formed a separate group together with Ceriporiopsis guidella and Phlebia spp. in the phlebioid clade. In this clade, the closely related species Ceriporiopsis resinascens and Ceriporiopsis pseudogilvescens grouped together with Ceriporiopsis aneirina. C. resinascens and C. pseudogilvescens have identical LSU and SSU sequences but differ in ITS. Ceriporiopsis pannocincta also fell in the phlebioid clade, but showed closer proximity to Gloeoporus dichrous than to C. gilvescens or C. aneirina-C. pseudogilvescens-C. resinascens group. Another clade was composed of a Ceriporiopsis balaenae-Ceriporiopsis consobrina group and was found to be closely related to Antrodiella and Frantisekia, with the overall clade highly reminiscent of the residual polyporoid clade. The monotypic genus Pouzaroporia, erected in the past for Ceriporiopsis subrufa due to its remarkable morphological differences, also fell within the residual polyporoid clade. Ceriporiopsis subvermispora held an isolated position from the other species of the genus. Therefore, the previously proposed name Gelatoporia subvermispora has been adopted for this species. Physisporinus rivulosus appeared unrelated to two other European Physisporinus species. Moreover, Ceriporiopsis (=Skeletocutis) jelicii grouped in a separate clade, distinct from Ceriporiopsis species. Finally, the ITS data demonstrated the proximity of some Ceriporiopsis species (Ceriporiopsis portcrosensis and Ceriporiopsis subsphaerospora) to Skeletocutis amorpha.

Oxalate efflux transporter from the brown rot fungus Fomitopsis palustris.

An oxalate-fermenting brown rot fungus, Fomitopsis palustris, secretes large amounts of oxalic acid during wood decay. Secretion of oxalic acid is indispensable for the degradation of wood cell walls, but almost nothing is known about the transport mechanism by which oxalic acid is secreted from F. palustris hyphal cells. We characterized the mechanism for oxalate transport using membrane vesicles of F. palustris. Oxalate transport in F. palustris was ATP dependent and was strongly inhibited by several inhibitors, such as valinomycin and NH(4)(+), suggesting the presence of a secondary oxalate transporter in this fungus. We then isolated a cDNA, FpOAR (Fomitopsis palustris oxalic acid resistance), from F. palustris by functional screening of yeast transformants with cDNAs grown on oxalic acid-containing plates. FpOAR is predicted to be a membrane protein that possesses six transmembrane domains but shows no similarity with known oxalate transporters. The yeast transformant possessing FpOAR (FpOAR-transformant) acquired resistance to oxalic acid and contained less oxalate than the control transformant. Biochemical analyses using membrane vesicles of the FpOAR-transformant showed that the oxalate transport property of FpOAR was consistent with that observed in membrane vesicles of F. palustris. The quantity of FpOAR transcripts was correlated with increasing oxalic acid accumulation in the culture medium and was induced when exogenous oxalate was added to the medium. These results strongly suggest that FpOAR plays an important role in wood decay by acting as a secondary transporter responsible for secretion of oxalate by F. palustris.

Hydroquinone and HO differentially affect the ultrastructure and expression of ligninolytic genes in the basidiomycete Ceriporiopsis subvermispora.

The biodegradation of lignin is a highly oxidative process in which various oxidases and peroxidases play a major role. During lignin decay, the generation of aromatic compounds and reactive oxygen species leads to oxidative stress. In this work, the effect of the oxidative compounds H(2)O(2) and hydroquinone in the ligninolytic fungus Ceriporiopsis subvermispora was studied, both at the ultrastructural and at the transcriptional level. Transmission electron microscopy revealed the presence of microvesicles and extensive cytoplasm degeneration after incubation with hydroquinone, but not with H(2)O(2). Studies of the intracellular redox state of the fungus showed that hydroquinone causes a transient decrease in the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio and an increase in the glutathione-S-transferase mRNA levels. These results suggest that hydroquinone produces oxidative stress in this microorganism. On the other hand, it was observed that hydroquinone, but not H(2)O(2), affects Mn-dependent peroxide and laccase transcripts levels. We propose that the mechanism by which the fungus reacts against oxidative stress contributes to its selectivity toward lignin during wood decay.

Genetic variation and relationships in Laetiporus sulphureus s. lat., as determined by ITS rDNA sequences and in vitro growth rate.

The aim of this study was to characterise the genetic variation and molecular relationships of the brown rot polypore, Laetiporus sulphureus s. lat., from Europe, South America, Africa, and Asia, using ITS sequences of the nu-rDNA and by comparing the growth rate in vitro. In a NJ analysis of the sequences of 130 individuals of L. sulphureus s. lat., eight distinct clusters emerged, supported by BS values of 70-100%. Within each cluster, the ITS rDNA sequence variation was below 3%. The sequences were also analysed together with Laetiporus sequences available from GenBank. Results demonstrated the possible presence of L. huroniensis in Europe (invalidly named L. montanus) and L. gilbertsonii in South America, and provided more information on the Pan-American and European distribution of one of the clades, currently known in North America as L. sulphureus. L. conifericola formed a separate distinct clade. Moreover, the analysis revealed two unknown Laetiporus taxa in Korea, one in South Africa, and one in Europe. As L. sulphureus is described from Europe (France), and we show that more than one taxon exist here, it is presently not possible to define L. sulphureus s. str. Certain biological differences between some of the clades (in vitro growth rates, chemical composition, and pigmentation) were demonstrated and discussed.