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Chaetopyranin, a benzaldehyde derivative, and other related metabolites from Chaetomium globosum, an endophytic fungus derived from the marine red alga Polysiphonia urceolata.

Cultivation of the endophytic fungus Chaetomium globosum, which was isolated from the inner tissue of the marine red alga Polysiphonia urceolata, resulted in the isolation of chaetopyranin (1), a new benzaldehyde secondary metabolite. Ten known compounds were also isolated, including two benzaldehyde congeners, 2-(2',3-epoxy-1',3'-heptadienyl)-6-hydroxy-5-(3-methyl-2-butenyl)benzaldehyde (2) and isotetrahydroauroglaucin (3), two anthraquinone derivatives, erythroglaucin (4) and parietin (5), five asperentin derivatives including asperentin (6, also known as cladosporin), 5'-hydroxy-asperentin-8-methylether (7), asperentin-8-methyl ether (8), 4'-hydroxyasperentin (9), and 5'-hydroxyasperentin (10), and the prenylated diketopiperazine congener neoechinulin A (11). The structures of these compounds were determined on the basis of their spectroscopic data analysis (1H, 13C, 1H-1H COSY, HMQC, and HMBC NMR, as well as low- and high-resolution mass experiments). To our knowledge, compound 1 represents the first example of a 2H-benzopyran derivative of marine algal-derived fungi as well as of the fungal genus Chaetomium. Each isolate was tested for its DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging property. Compounds 1-4 were found to have moderate activity. Chaetopyranin (1) also exhibited moderate to weak cytotoxic activity toward several tumor cell lines.

Animals↗

Phaeohyphomycosis caused by Chaetomium globosum in an allogeneic bone marrow transplant recipient.

Bone marrow transplant recipients are highly susceptible to opportunistic fungal infections. This is the report, of the first case of a Chaetomium systemic infection described in Brazil. A 34 year-old patient with chronic myeloid leukemia underwent an allogeneic sibling matched bone marrow transplant. Seven months later, he developed systemic infection with enlargement of the axillary and cervical lymph nodes. Culture of the aspirates from both lymph nodes yielded Chaetomium globosum. The infection was successfully treated with amphotericin B. The increasing population of immunosupressed patients requires a careful microbiologic investigation for uncommon fungal infections.

Adult↗

Cerebral fungal infections in the immunocompromised host: a literature review and a new pathogen--Chaetomium atrobrunneum: case report.

OBJECTIVE AND IMPORTANCE: A case of a cerebral abscess, occurring in a patient who had undergone bone marrow transplant, caused by a new pathogen, Chaetomium atrobrunneum, and a review of the literature are presented. Although Aspergillus species are by far the most common fungi found in cerebral abscesses in immunocompromised patients, an increasing number of fungi commonly found in nature but not usually associated with infections in humans have been isolated from cerebral abscesses in these patients. CLINICAL PRESENTATION: A 31-year-old male patient, who had undergone a recent bone marrow transplantation for multiple myeloma, presented 3 months after transplantation with right-sided hemiplegia caused by a left parietal hemorrhagic lesion. INTERVENTION: A biopsy guided by computed tomography showed that the abscess contained the fungus C. atrobrunneum. The final identification of the organism was based on cultures, scanning electron microscopic studies, and consultation with the Fungus Testing Laboratory at the University of Texas Health Science Center, San Antonio, TX. The patient was treated with several antifungal medications but developed uncontrolled cerebral edema, which led to further neurological deterioration and eventual death. CONCLUSION: Cerebral abscesses in the immunocompromised patient may no longer be assumed to be caused solely by Aspergillus species. The literature reveals several rare cases of uncommon fungi found in these abscesses. Only four cases of cerebral infections caused by the genus Chaetomium have been reported. The case presented represents the first time a patient who had undergone a bone marrow transplant with a cerebral abscess was found to be caused by the pathogen C. atrobrunneum.

Adult↗

Chaetomium pneumonia in patient with acute myeloid leukaemia.

A patient with relapsed refractory acute myeloid leukaemia developed typical fungal lung lesions despite intravenous amphotericin B prophylaxis. Chaetomium globosum was cultured from the resected right lower lobe. Histology showed branching hyphae negative for common Aspergillus species by immunohistochemical staining. Previous reports of invasive disease caused by Chaetomium and some applications of immunohistochemical staining for Aspergillus are discussed.

Adult↗

The production of chaetoglobosins, sterigmatocystin, O-methylsterigmatocystin, and chaetocin by Chaetomium spp. and related fungi.

Production of mycotoxins by Chaetomium spp. and related fungi on rice culture was examined by a combination of cytotoxicity tests using HeLa cells and thin-layer chromatography. Three species, C. mollipilium, C. rectum, and C. subaffine, as well as C. cochliodes and C. globosum, were proved to produce chaetoglobosins. From cultures of four strains of Chaetomium sp., assigned to C. thielavioideum, and one strain of Farrowia sp., chaetocin, sterigmatocystin, and O-methylsterigmatocystin were isolated. Morphological characteristics of the producers of sterigmatocystins are described.

Ascomycota↗

Onychomycosis caused by Chaetomium globosum Kunze.

In this paper we report a case of onychomycosis caused by Chaetomium globosum. The patient had lesions of the fingernails of the left hand. The direct microscopical examination of the nails showed light-brown hyphae with thick-walled cells. The histopathological examination revealed thick aggregated hyphal element in the nail plate. Amongst the antimycotics tested oxiconazole with MIC values of 0.3 microgram/ml-1 was found to be most effective in vitro against Chaetomium globosum.

Adult↗

[Effect of Chaetomium cochliodes Palliser on micromycetes of the root zone of spring barley].

The paper deals with the studies in species composition of micromycetes of the meadow-chernozem deleached soil in the root zone of spring barley and their interaction with the strain of fungus-antagonist Chaetomium cochliodes 3250, which served a basis for creation of the preparation--chetomik to protect plants from the root diseases agents. Differences were established between mycobiota of soil and root zone of plants; the most considerable ones are the differences between soil rhizoplane: the decrease of special diversity, changes in the number composition of numerous micromycete species. It has been shown that Chaetomium cochliodes 3250 manifests high antagonistic activity with respect to saprophytic and, especially, phytopathogenic fungi isolated from soil of spaces between rows, rhizosphere as well as rhizoplane of the spring barley which evidences for expediency of this strain use as the means of the culture protection from the root rots.

Fungi↗

Extracellular beta-D-glucosidase from Chaetomium thermophilum var. coprophilum: production, purification and some biochemical properties.

The thermophilic fungus Chaetomium thermophilum var. coprophilum produced large amounts of extracellular and intracellular beta-glucosidase activity when grown on cellulose or cellobiose as carbon sources. The presence of glucose in the culture medium drastically decreased the level of beta-glucosidase activity, while cycloheximide prevented the induction of the extracellular enzyme activity by cellobiose. An extracellular beta-glucosidase induced by avicel was purified by a procedure involving acetone precipitation and chromatography on two DEAE-cellulose columns. The purified enzyme was a basic protein, with a carbohydrate content of 73%. The deglycosylated enzyme exhibited a molecular mass of 43 kDa, with pH and temperature optima of 5.5 and 65 degrees C respectively. The beta-glucosidase hydrolysed only cellobiose and p-nitrophenyl-beta-D-glucopyranoside, exhibiting apparent Km values of 3.13 mM and 0.76 mM, respectively. The native purified enzyme was stable up to 2 hours at 60 degrees C, and its thermal stability was directly dependent on glycosylation.

Cellobiose↗

SCP production by Chaetomium cellulolyticum, a new thermotolerant cellulolytic fungus.

Chaetomium cellulolyticum, a newly isolated cellulolytic fungus, showed 50-100% faster growth rates and over 80% more final biomass-protein formation than Trichoderma viride, a well-known high cellulase-producing cellulolytic organism, when cultivated on Solka-floc (a purified, predominantly amorphorous form of cellulose) or partially delignified sawdust (consisting of a mixture of hardwoods) as the sole-carbon source in the fermentation media. However, in both cases, T, viride produced much higher quantities of free cellulases at faster rates and also degraded more substrate than C. cellulolyticum. It is concluded that the synthesis mechanisms and/or the nature of the cellulase complexes of the two types of organisms are quite different such taht C. cellulolyticum is more optimal for single-cell protein (SCP) production, while T. viride is more optimal for the production of extracellular cellulase. It was also found that the amino acid composition of C. cellulolyticum is generally better than that of T. viride and compares favorably with those of the FAO reference protein, alfalfa, and soya meal. In addition, preliminary feeding trials on rats have shown no adverse effects of the SCP produced by C. cellulolyticum fermentations.

Amino Acids↗

Analysis of the heat-shock response displayed by two Chaetomium species originating from different thermal environments.

Three features of the heat shock response, reorganization of protein expression, intracellular accumulation of trehalose, and alteration in unsaturation degree of fatty acids were investigated in the thermophilic fungus Chaetomium thermophile and compared to the response displayed by a closely related mesophilic species, C. brasiliense. Thermophilic heat shock response paralleled the mesophilic response in many respects like (i) the temperature difference observed between normothermia and the upper limit of translational activity, (ii) the transient nature of the heat shock response at the level of protein expression including both the induction of heat shock proteins (HSPs) as well as the repression of housekeeping proteins, (iii) the presence of representatives of high-molecular-weight HSPs families, (iv) intracellular accumulation of trehalose, and finally (v) modifications in fatty acid composition. On the other hand, a great variability between the two organisms was observed for the proteins expressed during stress, in particular a protein of the HSP60 family that was only observed in C. thermophile. This peptide was also present constitutively at normal temperature and may thus fulfil thermophilic functions. It is shown that accumulation of trehalose does not play a part in thermophily but is only a stress response. C. thermophile contains less polyunsaturated fatty acids at normal temperature than C. brasiliense, a fact that can be directly related to thermophily. When subjected to heat stress, both organisms tended to accumulate shorter and less unsaturated fatty acids.

Chaetomium↗

Two family G xylanase genes from Chaetomium gracile and their expression in Aspergillus nidulans.

With oligonucleotides based on the amino-terminal and internal amino-acid sequences of a xylanase, two xylanase genes, cgxA and cgxB, were isolated and sequenced from Chaetomium gracile wild and mutant strains. Each gene isolated from both strains was essentially the same as far as nucleotide sequences were compared. The mature CgXA and CgXB xylanases comprise 189 and 211 amino acids, respectively, and share 68.5% homology. The CgXA was found to be the major enzyme in the mutant strain. Comparison of these amino-acid sequences with xylanase sequences from other origins showed that they have a high degree of identity to the family G xylanases. The cgxA and cgxB genes were introduced into Aspergillus nidulans and found to be expressed with their own promoters.

Amino Acid Sequence↗

Synthesis of sterigmatocystin on a chemically defined medium by species of Aspergillus and Chaetomium.

Sterigmatocystin (ST) is a secondary metabolite and a principal mycotoxin known to be produced by over 30 species of filamentous fungi. It is also one of the late intermediates in aflatoxin biosynthesis. We have tested the ability of 7 species of Aspergillus, including 4 strains of A. versicolor, one species of Bipolaris, and two species of Chaetomium, to produce ST on a sucrose-salts-phenylalanine defined medium as well as on three complex substrates. Highest ST production in our survey was by a strain of A. versicolor grown on wheat, whereas, the highest ST production on defined medium was by C. cellulolyticum. To our knowledge, this is the first report of ST production by C. cellulolyticum on any substrate. In precursor feeding studies, resting cultures of wild type A. nidulans and A. versicolor were unable to biotransform O-methylsterigmatocystin (OMST), the last known intermediate in aflatoxin biosynthesis. These results suggest that ST is the end product of polyketide metabolism in the strains tested.

Aspergillus↗

Comparative studies on the role of nitrogenous compounds in the growth and perithecial development of Chaetomium aureum.

Sodium nitrate is a suitable nitrogen source supporting growth and perithecial formation in Chaetomium aureum. 31 inorganic and organic nitrogen sources at a concentration of 0.033% were used at different incubating temperatures (25, 30 and 35 degrees C). The cultures were grown in Petri dishes, culture tubes and Erlenmeyer flasks. An incubating temperature of 30 degrees C was found most suitable for perithecial formation. In general, a nitrogen source in a solid medium could induce better perithecial production than in liquid media.

Amino Acids↗

Isolation of a novel thermophilic fungus Chaetomium sp. nov. MS-017 and description of its palm-oil mill fiber-decomposing properties.

Palm-oil mill fiber (POMF) is a fibrous, natural hard material discharged in enormous amounts from palm-oil mills in tropical plantations; therefore, research to find microorganisms that decompose POMF was conducted. As the result of screening, a new thermophilic fungus, Chaetomium sp. nov. MS-017, exhibiting rapid growth on POMF was isolated from rotted wood. Based on partial characterization of the decomposition of POMF, it was shown that MS-017 preferentially assimilates polysaccharides, especially hemicelluloses such as xylan. A preliminary composting study indicated that MS-017 produced 855 g of decomposed product from 1,000 g of intact POMF in 12 days under optimized solid-culture conditions. The decomposition rate of POMF was 23% (w/w), and the cell yield calculated from consumed POMF was as high as 36% (w/w). These results indicate that MS-017 has a very high potential to decompose POMF and that it is suitable for economical production of compost to recycle by-product biomass from oil-palm plantations.

Biodegradation, Environmental↗

Bioconversion of (+)-valencene in submerged cultures of the ascomycete Chaetomium globosum.

Submerged cultures of the ascomycete Chaetomium globosum oxidised the exogenous sesquiterpene (+)-valencene to nootkatone via the stereoselective generation of alpha-nootkatol. Inhibition experiments suggested that the first introduction of oxygen, the rate-limiting step of the bioconversion, may have been catalysed by a cytochrome-P450-monooxygenase. However, nootkatone was not the final metabolite: further flavour-active and inactive, non-volatile oxidation products were identified. (+)-Valencene and the flavour-active mono-oxyfunctionalised transformation products, alpha-nootkatol, nootkatone, and valencene-11,12-epoxide accumulated preferably inside the fungal cells. Di- and poly-oxygenated products, such as nootkatone-11,12-epoxide, were found solely in the culture medium, indicating an active transport of these metabolites into the extracellular compartment during (+)-valencene detoxification. These metabolic properties may have contributed to the high tolerance of the fungus towards the exogenous hydrocarbon.

Biotechnology↗

Expressed sequence tags-based identification of genes in the biocontrol agent Chaetomium cupreum.

Chaetomium cupreum has a potential as biocontrol agent against a range of plant pathogens on the basis of production of antifungal metabolites, mycoparasitism, competition for space and nutrients, or various combinations of these. To explore genes expressed in C. cupreum, a cDNA library was constructed from mycelium and 3,066 expressed sequence tags (ESTs) were generated. Clusters analysis enabled the identification of 1,471 unigenes with 392 contigs and 1,079 singleton sequences. Putative functions were assigned to 874 unigenes that exhibited strong similarity to genes/ESTs in public databases putatively containing genes involved in cellular component, molecular function, and biological process. Other 597 ESTs representing novel genes showed no significant similarity to public database resource of NCBI. A proportion of genes was identified related to degradation of pathogen cell wall, antifungal metabolite production, as was estimated in the biocontrol fungus. The paper described is a first step towards the knowledge of the C. cupreum genome. The results present the useful application of EST analysis on C. cupreum and provide a preliminary indication of gene expression putatively involved in biocontrol.

Chaetomium↗

Filamentous marine fungi as producers of O-glycosylhydrolases: beta-1,3-glucanase from Chaetomium indicum.

Ninety fungal strains (42 species) isolated from marine habitats were studied for their ability to produce extracellular enzymes. Cultural filtrates of these strains were shown to contain a series of glycosidases (beta-glucosidases, N-acetyl-beta-glucosaminidases, beta-galactosidases alpha-mannosidases) and glucanases (1,3-beta-glucanases, amylases) which varied with habitat. The level of activity depended on the species of fungi. Several promising strains capable of producing both individual enzymes and a set of enzymes for splitting carbohydrate-containing compound have been isolated. Optimal conditions for growth of Chaetomium indicum and for biosynthesis of beta-1,3-glucanase were determined. beta-1,3-Glucanase was isolated using ion-exchange chromatography, ultrafiltration, and gel filtration. The presence of 2 enzyme forms was shown; both forms were exo-beta-1,3-glucanases.

Chaetomium↗