Stachybotrys chartarum: a fungus for our time

Assessment of antidiabetic activity of three Phenylspirodrimanes from fungus Stachybotrys chartarum MUT 3308 by ADME, QSAR, molecular docking and molecular dynamics simulation studies against protein tyrosine phosphatase 1B (PTP1B)

Phenylspirodrimanes (PSD) are the sesquiterpene quinone type meroterpenoids found in nature. PSDs are found to exhibit inhibitory activity against immunocomplex diseases, and tyrosine kinase receptors. Three of the different PSDs C1, C2, and C3 that have been reported to be isolated from the sponge-associated fungus Stachybotrys chartarum MUT 3308 are selected for studying their possible inhibitory effect against type 2 diabetes mellitus. Mechanistically, blocking protein tyrosine phosphatase 1B (PTP1B) helps to reduce the insulin resistance induction caused by the high expression of PTP1B. The QSAR, ADME, toxicity (T) study was carried out to predict the pharmacokinetic properties and the biological activities of the PSDs. PASS prediction web tool was used to find and select the target proteins 1NNY, and 2HNP. According to the molecular docking simulations, C1 and C2 showed better binding affinity of -8.5 kcal/mol, and -8.1 kcal/mol respectively against 1NNY compared to the control ligand. RMSD, RMSF, Rg, and SASA analysis revealed that both C1, and C2 showed better stability, minor conformational changes, and minor fluctuation upon binding to PTP1B. Protein contact analysis was carried out to validate the residues that are in contact with the ligands according to molecular docking studies. Overall, C1, and C2 could be proposed as novel natural hits to be developed and small modifications of these PSDs could result in inducing the binding affinity significantly, although experimental validation is required for further evaluation of the work.Communicated by Ramaswamy H. Sarma.

New Phenylspirodrimanes from the Sponge-Associated Fungus Stachybotrys chartarum MUT 3308

Two phenylspirodrimanes, never isolated before, stachybotrin J (1) and new stachybocin G (epi-stachybocin A) (2), along with the already reported stachybotrin I (3), stachybotrin H (4), stachybotrylactam (5), stachybotrylactam acetate (6), 2α-acetoxystachybotrylactam acetate (7), stachybotramide (8), chartarlactam B (9), and F1839-J (10) were isolated from the sponge-associated fungus Stachybotrys chartarum MUT 3308. Their structures were established based on extensive spectrometric (HRMS) and spectroscopic (1D and 2D NMR) analyses. Absolute configurations of the stereogenic centers of stachybotrin J (1), stachybocin G (2), and stachybotrin I (3), were determined by comparison of their experimental circular dichroism (CD) spectra with their time-dependent density functional theory (TD-DFT) circular dichroism (ECD) spectra. The putative structures of seventeen additional phenylspirodrimanes were proposed by analysis of their respective MS/MS spectra through a Feature-Based Molecular Networking approach. All the isolated compounds were evaluated for their cytotoxicity against five aggressive cancer cell lines (MP41, 786, 786R, CAL33, and CAL33RR), notably including two resistant human cancer cell lines (786R, CAL33RR), and compounds 5, 6, and 7 exhibited cytotoxicity with IC50 values in the range of 0.3−2.2 µM.

Semisynthetic Approach toward Biologically Active Derivatives of Phenylspirodrimanes from S. chartarum

The phenylspirodrimanes (PSDs) from Stachybotrys chartarum represent a structurally diverse group of meroterpenoids, which, on the one hand, exhibit a structural exclusivity since their occurrence is not known for any other species and, on the other hand, offer access to chemically and biologically active compounds. In this study, phenylspirodrimanes 1-3 were isolated from S. chartarum and their water-mediated Cannizzaro-type transformation was investigated using quantum chemical DFT calculations substantiated by LC-MS and NMR experiments. Considering the inhibitory activity of PSDs against proteolytic enzymes and their modulatory effect on plasminogen, PSDs 1-3 were used as a starting material for the synthesis of their corresponding biologically active lactams. To access the library of the PSD derivatives and screen them against physiologically relevant serine proteases, a microscale semisynthetic approach was developed. This allowed us to generate the library of 35 lactams, some of which showed the inhibitory activity against physiologically relevant serine proteases such as thrombin, FXIIa, FXa, and trypsin. Among them, the agmatine-derived lactam 16 showed the highest inhibitory activity against plasma coagulation factors and demonstrated the anticoagulant activity in two plasma coagulation tests. The semisynthetic lactams were significantly less toxic compared to their parental natural PSDs.

Analysis of mold and mycotoxins in naturally infested indoor building materials

Health issues of residents of mold-infested housing are reported on a regular basis, and reasons for the arising impairments can be manifold. One possible cause are the toxic secondary metabolite produced by indoor microfungi (mycotoxins). To enable a more thorough characterization of the exposure to mycotoxins in indoor environments, data on occurrence and quantities of mycotoxins is essential. In the presented study, 51 naturally mold-infested building material samples were analyzed applying a previously developed method based on ultra-high performance liquid chromatography (UHPLC) separation in combination with triple-quadrupole mass spectrometry (TQMS) detection. A total of 38 secondary metabolites derived from different indoor mold genera like Aspergillus, Fusarium, Penicillium, and Stachybotrys were analyzed, of which 16 were detectable in 28 samples. As both the spectrum of target analytes and the investigated sample matrices showed high chemical varieties, an alternative calibration approach was applied complementary to identify potentially emerging matrix effects during ionization and mass spectrometric detection. Overall, strong alterations of analyte signals were rare, and compensation of considerable matrix suppression/enhancement only had to be performed for certain samples. Besides mycotoxin determination and quantification, the presence of 18 different mold species was confirmed applying microbiological approaches in combination with macro- and microscopic identification according to DIN ISO 16000-17:2010-06. These results additionally highlight the diversity of mycotoxins potentially arising in indoor environments and leads to the assumption that indoor mycotoxin exposure stays an emerging topic of research, which has only just commenced.

In Vitro Metabolism of Phenylspirodrimanes Derived from the Indoor Fungus Stachybotrys

Fungi belonging to the genus Stachybotrys are frequently detected in water-damaged indoor environments, and a potential correlation between emerging health problems of inhabitants of affected housing and the fungi is controversially discussed. Secondary metabolites (i.e., mycotoxins) produced by Stachybotrys, such as the highly toxic macrocyclic trichothecenes (MCTs), are of potential concern to human health. The present study, however, focused on the potential effects of the more broadly and abundantly formed group of phenylspirodrimanes (PSDs). The phase I and II metabolism of four structurally different PSDs were investigated in vitro using hepatic models in combination with high-performance liquid chromatography high-resolution mass spectrometry (HPLC-HRMS) analysis. In addition to metabolite detection by HRMS, isolation and structure elucidation by nuclear magnetic resonance spectroscopy (NMR) was part of the conducted study as well.

Update on Stachybotrys chartarum-Black Mold Perceived as Toxigenic and Potentially Pathogenic to Humans

In nature, there are many species of fungi known to produce various mycotoxins, allergens and volatile organic compounds (VOCs), as well as the commonly known etiological agents of various types of mycoses. So far, none of them have provoked so much emotion among homeowners, builders, conservators, mycologists and clinicians as Stachybotrys chartarum. This species compared to fungi of the genera Fusarium and Aspergillus is not as frequently described to be a micromycete that is toxigenic and hazardous to human and animal health, but interest in it has been growing consistently for three decades. Depending on the authors of any given review article, attention is focused either on the clinical aspects alongside the role of this fungus in deterioration of biomaterials, or aspects related to its biology, ecology and taxonomic position. On the one hand, it is well established that inhalation of conidia, containing the highest concentrations of toxic metabolites, may cause serious damage to the mammalian lung, particularly with repeated exposure. On the other hand, we can find articles in which authors demonstrate that S. chartarum conidia can germinate and form hyphae in lungs but are not able to establish an effective infection. Finally, we can find case reports that suggest that S. chartarum infection is linked with acute pulmonary hemorrhage, based on fungal structures recovered from patient lung tissue. New scientific reports have verified the current state of knowledge and note that clinical significance of this fungus is exceedingly controversial. For these reasons, understanding S. chartarum requires reviewing the well-known toxigenic features and harmful factors associated with this fungus, by gathering the newest ones into a coherent whole. The research problem related to this fungus seems to be not overly publicized, and there is still a demand to truthfully define the real threats of S. chartarum and phylogenetically related species. The most important problem, which should be fully elucidated as soon as possible, remains the clarification of the pathogenicity of S. chartarum and related species. Maybe it is urgent time to ask a critical question, namely what exactly do we know 28 years after the outbreak of pulmonary hemorrhage in infants in Cleveland, Ohio, USA most likely caused by S. chartarum?

Sialyltransferase Inhibitors for the Treatment of Cancer Metastasis: Current Challenges and Future Perspectives

Potent, cell-permeable, and subtype-selective sialyltransferase inhibitors represent an attractive family of substances that can potentially be used for the clinical treatment of cancer metastasis. These substances operate by specifically inhibiting sialyltransferase-mediated hypersialylation of cell surface glycoproteins or glycolipids, which then blocks the sialic acid recognition pathway and leads to deterioration of cell motility and invasion. A vast amount of evidence for the in vitro and in vivo effects of sialyltransferase inhibition or knockdown on tumor progression and tumor cell metastasis or colonization has been accumulated over the past decades. In this regard, this review comprehensively discusses the results of studies that have led to the recent discovery and development of sialyltransferase inhibitors, their potential biomedical applications in the treatment of cancer metastasis, and their current limitations and future opportunities.

Artificial vs natural Stachybotrys infestation-Comparison of mycotoxin production on various building materials

The genus Stachybotrys belongs to filamentous fungi found in indoor environment, mostly on cellulose-rich substrates after water-damage. The major purpose of this study was to investigate the influence of different building materials in case of mold infestation on the mycotoxin production of Stachybotrys species. Fifteen Stachybotrys mycotoxins including satratoxins, phenylspirodrimanes, and recently discovered stachybotrychromenes were in the focus of the investigations. Artificial and natural infestations were compared to determine whether environmental factors, for example, time of growth, temperature, humidity, and material additives have an influence on the observed mycotoxin profiles. It turned out that mycotoxin profiles from Stachybotrys spp. on building materials can be influenced by cellulose, paints, and paste of the materials. The total toxin levels of artificially and naturally contaminated gypsum board samples ranged up to 30 µg/cm² , whereas wallpaper samples showed total toxin levels in the range of 20-66 µg/cm² . A naturally infested sample disclosed the conversion of the dialdehyde components to the corresponding lactone isomers under the influence of light.

Differentiation of S. chartarum (Ehrenb.) S. Hughes Chemotypes A and S via FT-IR Spectroscopy

Stachybotrys (S.) chartarum is a cellulolytic mould with the ability to produce highly cytotoxic macrocyclic trichothecenes. Two chemotypes are defined according to their ability to produce either atranones or satratoxins. S. chartarum has been well known as the causative agent of the lethal disease stachybotryotoxicosis in horses. Further investigations revealed that this disease is strictly correlated with the presence of macrocyclic trichothecenes. Furthermore, their occurrence in water-damaged buildings has been linked to adverse health effects such as the sick building syndrome. As the chemotypes cannot be characterized via phenotypic criteria, different methods such as PCR, MALDI–TOF MS, LC–MS/MS, thin-layer chromatography and cytotoxicity assays have been used so far. Fourier-transform-infrared spectroscopy (FT-IR) is commonly used for the differentiation of bacteria and yeasts, but this technique is also applicable to filamentous fungi. Hence, this study aimed at evaluating to which extent a reliable differentiation of S. chartarum chemotypes A and S is possible. Besides, another objective was to verify if the recently introduced third genotype of S. chartarum can be identified. Therefore, 28 strains including the two chemotypes and the third genotype H were cultivated on malt extract agar (MEA) and potato dextrose agar in three biological replicates. Each sample was applied to FT-IR measurements on day 7, 14 and 21 of cultivation. In this study, we achieved a distinction of the chemotypes A and S via FT-IR spectroscopy after incubation for 7 days on MEA. In terms of genotype differentiation, the PCR detecting satratoxin- and atranone-gene clusters remained the only applicable method.

Reisolation and NMR characterization of the satratoxins G and H

The exquisitely cytotoxic macrolides, satratoxins G and H, have been reisolated from a solvent extract of a rice culture inoculated with Stachybotrys chartarum to be used as high-purity reference compounds for analytical analyses. Extensive chromatographic separation realized the compounds that were fully recharacterized in two solvents by 1D- and 2D-NMR spectroscopy, revealing some discrepancies in the nuclear magnetic resonance (NMR) data as compared with the previously reported values found in the literature. Detailed spectra are provided in order to aid future identification and dereplication.

An Electrochemical Fiveplex Biochip Assay Based on Anti-Idiotypic Antibodies for Fast On-Site Detection of Bioterrorism Relevant Low Molecular Weight Toxins

Modern threats of bioterrorism force the need for multiple detection of biothreat agents to determine the presence or absence of such agents in suspicious samples. Here, we present a rapid electrochemical fiveplex biochip screening assay for detection of the bioterrorism relevant low molecular weight toxins saxitoxin, microcystin-LR, T-2 toxin, roridin A and aflatoxin B1 relying on anti-idiotypic antibodies as epitope-mimicking reagents. The proposed method avoids the use of potentially harmful toxin-protein conjugates usually mandatory for competitive immunoassays. The biochip is processed and analyzed on the automated and portable detection platform pBDi within 13.4 min. The fiveplex biochip assay revealed toxin group specificity to multiple congeners. Limits of detection were 1.2 ng/mL, 1.5 ng/mL, 0.4 ng/mL, 0.5 ng/mL and 0.6 ng/mL for saxitoxin, microcystin-LR, T-2 toxin, roridin A or aflatoxin B1, respectively. The robustness of the fiveplex biochip for real samples was demonstrated by detecting saxitoxin, microcystin-LR, HT-2 toxin, roridin A and aflatoxin B1 in contaminated human blood serum without elaborate sample preparation. Recovery rates were between 52–115% covering a wide concentration range. Thus, the developed robust fiveplex biochip assay can be used on-site to quickly detect one or multiple low molecular weight toxins in a single run.

Exploring Secondary Metabolite Profiles of Stachybotrys spp. by LC-MS/MS

The genus Stachybotrys produces a broad diversity of secondary metabolites, including macrocyclic trichothecenes, atranones, and phenylspirodrimanes. Although the class of the phenylspirodrimanes is the major one and consists of a multitude of metabolites bearing various structural modifications, few investigations have been carried out. Thus, the presented study deals with the quantitative determination of several secondary metabolites produced by distinct Stachybotrys species for comparison of their metabolite profiles. For that purpose, 15 of the primarily produced secondary metabolites were isolated from fungal cultures and structurally characterized in order to be used as analytical standards for the development of an LC-MS/MS multimethod. The developed method was applied to the analysis of micro-scale extracts from 5 different Stachybotrys strains, which were cultured on different media. In that process, spontaneous dialdehyde/lactone isomerization was observed for some of the isolated secondary metabolites, and novel stachybotrychromenes were quantitatively investigated for the first time. The metabolite profiles of Stachybotrys species are considerably influenced by time of growth and substrate availability, as well as the individual biosynthetic potential of the respective species. Regarding the reported adverse effects associated with Stachybotrys growth in building environments, combinatory effects of the investigated secondary metabolites should be addressed and the role of the phenylspirodrimanes re-evaluated in future research.

Stachybotrychromenes A-C: novel cytotoxic meroterpenoids from Stachybotrys sp

In the course of gaining new insights into the secondary metabolite profile of various Stachybotrys strains, in particular concerning triprenyl phenol-like compounds, so far, unknown metabolites with analogous structural features were discovered. Three novel meroterpenoids containing a chromene ring moiety, namely stachybotrychromenes A–C, were isolated from solid culture of the filamentous fungus Stachybotrys chartarum DSMZ 12880 (chemotype S). Their structures were elucidated by means of comprehensive spectroscopic analysis (1D and 2D NMR, ESI-HRMS, and CD) as well as by comparison with spectroscopic data of structural analogues described in literature. Stachybotrychromenes A and B exhibited moderate cytotoxic effects on HepG2 cells after 24 h with corresponding IC₅₀ values of 73.7 and 28.2 μM, respectively. Stachybotrychromene C showed no significant cytotoxic activity up to 100 μM. Moreover, it is noteworthy that stachybotrychromenes A–C are produced not only by S. chartarum chemotype S but also S. chartarum chemotype A and Stachybotrys chlorohalonata.

Structure of melanins from the fungi Ochroconis lascauxensis and Ochroconis anomala contaminating rock art in the Lascaux Cave

Two novel species of the fungal genus Ochroconis, O. lascauxensis and O. anomala have been isolated from the walls of the Lascaux Cave, France. The interest in these fungi and their melanins lies in the formation of black stains on the walls and rock art which threatens the integrity of the paintings. Here we report solid-state cross polarization magic-angle spinning ¹³C and ¹⁵N nuclear magnetic resonance (NMR) spectroscopy and surface-enhanced Raman spectroscopy (SERS) of the melanins extracted from the mycelia of O. lascauxensis and O. anomala in order to known their chemical structure. The melanins from these two species were compared with those from other fungi. The melanins from the Ochroconis species have similar SERS and ¹³C and ¹⁵N NMR spectra. Their chemical structures as suggested by the data are not related to 3,4-dihydroxyphenylalanine, 5,6-dihydroxyindole or 1,8-dihydroxynaphthalene precursors and likely the building blocks from the melanins have to be based on other phenols that react with the N-terminal amino acid of proteins. The analytical pyrolysis of the acid hydrolysed melanin from O. lascauxensis supports this assumption.

Identification and Characterisation of a Novel Protein FIP-sch3 from Stachybotrys chartarum

In this study, a novel FIP named FIP-sch3 has been identified and characterised. FIP-sch3 was identified in the ascomycete Stachybotrys chartarum, making it the second FIP to be identified outside the order of Basidiomycota. Recombinant FIP-sch3 (rFIP-shc3) was produced in Escherichia coli and purified using GST-affinity magnetic beads. The bioactive characteristics of FIP-sch3 were compared to those of well-known FIPs LZ-8 from Ganoderma lucidum and FIP-fve from Flammulina velutipes, which were produced and purified using the same method. The purified rFIP-sch3 exhibited a broad spectrum of anti-tumour activity in several types of tumour cells but had no cytotoxicity in normal human embryonic kidney 293 cells. Assays that were implemented to study these properties indicated that rFIP-sch3 significantly suppressed cell proliferation, induced apoptosis and inhibited cell migration in human lung adenocarcinoma A549 cells. The anti-tumour effects of rFIP-sch3 in A549 cells were comparable to those of rLZ-8, but they were significantly greater than those of rFIP-fve. Molecular assays that were built on real-time PCR further revealed potential mechanisms related to apoptosis and migration and that underlie phenotypic effects. These results indicate that FIP-shc3 has a unique anti-tumour bioactive profile, as do other FIPs, which provide a foundation for further studies on anti-tumour mechanisms. Importantly, this study also had convenient access to FIP-sch3 with potential human therapeutic applications.

Stachybotrys mycotoxins: from culture extracts to dust samples

The filamentous fungus Stachybotrys chartarum is known for its toxic metabolites and has been associated with serious health problems, including mycotoxicosis, among occupants of contaminated buildings. Here, we present results from a case study, where an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for known and tentatively identified compounds characterized via UHPLC-quadruple time-of-flight (QTOF) screening of fungal culture extracts, wall scrapings and reference standards. The UHPLC-MS/MS method was able to identify 12 Stachybotrys metabolites, of which four could be quantified based on authentic standards and a further six estimated based on similarity to authentic standards. Samples collected from walls contaminated by S. chartarum in a water-damaged building showed that the two known chemotypes, S and A, coexisted. More importantly, a link between mycotoxin concentrations found on contaminated surfaces and in settled dust was made. One dust sample, collected from a water-damaged room, contained 10 pg/cm(2) macrocyclic trichothecenes (roridin E). For the first time, more than one spirocyclic drimane was detected in dust. Spirocyclic drimanes were detected in all 11 analysed dust samples and in total amounted to 600 pg/cm(2) in the water-damaged room and 340 pg/cm(2) in rooms adjacent to the water-damaged area. Their wide distribution in detectable amounts in dust suggested they could be good candidates for exposure biomarkers. Graphical abstract Stachybotrys growing on a gypsum board, and some of the compounds it produces.

Rhinitis, Ocular, Throat and Dermal Symptoms, Headache and Tiredness among Students in Schools from Johor Bahru, Malaysia: Associations with Fungal DNA and Mycotoxins in Classroom Dust

There are few studies on rhinitis and sick building syndrome (SBS) among students in tropical countries. We studied associations between levels of five fungal DNA sequences, two mycotoxins (sterigmatocystin and verrucarol) and cat allergen (Fel d 1) levels in schools and rhinitis and other weekly SBS symptoms in the students. Fungal DNA was measured by quantitative PCR and cat allergen by ELISA. Pupils (N = 462) from eight randomly selected schools in Johor Bahru, Malaysia participated (96%). Dust samples were collected by cotton swabs and Petri dishes exposed for one week. None of the schools had a mechanical ventilation system, but all classrooms had openable windows that were kept open during lectures and indoor CO2 levels were low (mean 492 ppm; range 380-690 ppm). Weekly nasal symptoms (rhinitis) (18.8%), ocular (11.6%), throat (11.1%), dermal symptoms, headache (20.6%) and tiredness (22.1%) were common. Total fungal DNA in swab samples was associated with rhinitis (p = 0.02), ocular symptoms (p = 0.009) and tiredness (p = 0.001). There were positive associations between Aspergillus versicolor DNA in Petri dish samples, ocular symptoms (p = 0.02) and tiredness (p = 0.001). The level of the mycotoxin verrucarol (produced by Stachybotrys chartarum) in swab samples was positively associated with tiredness (p = 0.04). Streptomyces DNA in swab samples (p = 0.03) and Petri dish samples (p = 0.03) were negatively associated with tiredness. In conclusion, total fungal contamination, measured as total fungal DNA) in the classrooms, Aspergillus versicolor and verrucarol can be risk factors for rhinitis and SBS symptoms among students in the tropical country Malaysia.

Systematic Review of the Use of Phytochemicals for Management of Pain in Cancer Therapy

Pain in cancer therapy is a common condition and there is a need for new options in therapeutic management. While phytochemicals have been proposed as one pain management solution, knowledge of their utility is limited. The objective of this study was to perform a systematic review of the biomedical literature for the use of phytochemicals for management of cancer therapy pain in human subjects. Of an initial database search of 1,603 abstracts, 32 full-text articles were eligible for further assessment. Only 7 of these articles met all inclusion criteria for this systematic review. The average relative risk of phytochemical versus control was 1.03 [95% CI 0.59 to 2.06]. In other words (although not statistically significant), patients treated with phytochemicals were slightly more likely than patients treated with control to obtain successful management of pain in cancer therapy. We identified a lack of quality research literature on this subject and thus were unable to demonstrate a clear therapeutic benefit for either general or specific use of phytochemicals in the management of cancer pain. This lack of data is especially apparent for psychotropic phytochemicals, such as the Cannabis plant (marijuana). Additional implications of our findings are also explored.

Genome Sequence of Stachybotrys chartarum Strain 51-11

The Stachybotrys chartarum strain 51-11 genome was sequenced by shotgun sequencing utilizing Illumina HiSeq 2000 and PacBio technologies. Since S. chartarum has been implicated as having health impacts within water-damaged buildings, any information extracted from the genomic sequence data relating to toxins or the metabolism of the fungus might be useful.

Identification of signatory secondary metabolites during mycoparasitism of Rhizoctonia solani by Stachybotrys elegans

Stachybotrys elegans is able to parasitize the fungal plant pathogen Rhizoctonia solani AG-3 following a complex and intimate interaction, which, among others, includes the production of cell wall-degrading enzymes, intracellular colonization, and expression of pathogenic process encoding genes. However, information on the metabolome level is non-existent during mycoparasitism. Here, we performed a direct-infusion mass spectrometry (DIMS) metabolomics analysis using an LTQ Orbitrap analyzer in order to detect changes in the profiles of induced secondary metabolites of both partners during this mycoparasitic interaction 4 and 5 days following its establishment. The diketopiperazine(s) (DKPs) cyclo(S-Pro-S-Leu)/cyclo(S-Pro-S-Ile), ethyl 2-phenylacetate, and 3-nitro-4-hydroxybenzoic acid were detected as the primary response of Rhizoctonia 4 days following dual-culturing with Stachybotrys, whereas only the latter metabolite was up-regulated 1 day later. On the other hand, trichothecenes and atranones were mycoparasite-derived metabolites identified during mycoparasitism 4 and 5 days following dual-culturing. All the above secondary metabolites are known to exhibit bioactivity, including fungitoxicity, and represent key elements that determine the outcome of the interaction being studied. Results could be further exploited in programs for the evaluation of the bioactivity of these metabolites per se or their chemical analogs, and/or genetic engineering programs to obtain more efficient mycoparasite strains with improved efficacy and toxicological profiles.

Occurrence of Stachybotrys chartarum chemotype S in dried culinary herbs

Stachybotrys (S.) chartarum is an omnipresent cellulolytic mould which produces secondary metabolites, such as the highly toxic macrocyclic trichothecenes. While it is known to occur in animal feed like hay and straw as well as in water-damaged indoor environments, there is little knowledge about the occurrence of S. chartarum and its secondary metabolites in food. The objective of the present study was to examine selected dried culinary herbs for the presence of S. chartarum chemotype S, to assess the potential risk of a contamination of foods with macrocyclic trichothecenes. In total, 50 Stachybotrys isolates from different types of culinary herbs (n=100) such as marjoram (Origanum majorana Linné (L.)), oregano (Origanum vulgare L.), thyme (Thymus vulgaris L.), and savory (Satureja hortensis L.) were examined by MTT-cell culture test (effect-based bioassay), ELISA, and by liquid chromatography tandem mass spectrometry (LC-MS/MS). Selected toxic and non-toxic isolates (n=15) were genetically characterized by PCR and sequencing. Five isolates (10%) were highly toxic in the MTT-cell culture test, and the production of macrocyclic trichothecenes was proven by ELISA and LC-MS/MS. These five isolates were genetically confirmed as S. chartarum chemotype S. To the best of our knowledge, this is the first report about a contamination of dried culinary herbs with toxigenic S. chartarum.

Comparative genome sequencing reveals chemotype-specific gene clusters in the toxigenic black mold Stachybotrys

BACKGROUND

The fungal genus Stachybotrys produces several diverse toxins that affect human health. Its strains comprise two mutually-exclusive toxin chemotypes, one producing satratoxins, which are a subclass of trichothecenes, and the other producing the less-toxic atranones. To determine the genetic basis for chemotype-specific differences in toxin production, the genomes of four Stachybotrys strains were sequenced and assembled de novo. Two of these strains produce atranones and two produce satratoxins.

RESULTS

Comparative analysis of these four 35-Mbp genomes revealed several chemotype-specific gene clusters that are predicted to make secondary metabolites. The largest, which was named the core atranone cluster, encodes 14 proteins that may suffice to produce all observed atranone compounds via reactions that include an unusual Baeyer-Villiger oxidation. Satratoxins are suggested to be made by products of multiple gene clusters that encode 21 proteins in all, including polyketide synthases, acetyltransferases, and other enzymes expected to modify the trichothecene skeleton. One such satratoxin chemotype-specific cluster is adjacent to the core trichothecene cluster, which has diverged from those of other trichothecene producers to contain a unique polyketide synthase.

CONCLUSIONS

The results suggest that chemotype-specific gene clusters are likely the genetic basis for the mutually-exclusive toxin chemotypes of Stachybotrys. A unified biochemical model for Stachybotrys toxin production is presented. Overall, the four genomes described here will be useful for ongoing studies of this mold's diverse toxicity mechanisms.

Microbial volatile organic compound emissions from Stachybotrys chartarum growing on gypsum wallboard and ceiling tile

BACKGROUND

Stachybotrys chartarum is a filamentous mold frequently identified among the mycobiota of water-damaged building materials. Growth of S. chartarum on suitable substrates and under favorable environmental conditions leads to the production of secondary metabolites such as mycotoxins and microbial volatile organic compounds (MVOCs). The aim of this study was to characterize MVOC emission profiles of seven toxigenic strains of S. chartarum, isolated from water-damaged buildings, in order to identify unique MVOCs generated during growth on gypsum wallboard and ceiling tile coupons. Inoculated coupons were incubated and monitored for emissions and growth using a closed glass environmental growth chamber maintained at a constant room temperature. Gas samples were collected from the headspace for three to four weeks using Tenax TA tubes.

RESULTS

Most of the MVOCs identified were alcohols, ketones, ethers and esters. The data showed that anisole (methoxybenzene) was emitted from all of the S. chartarum strains tested on both types of substrates. Maximum anisole concentration was detected after seven days of incubation.

CONCLUSIONS

MVOCs are suitable markers for fungal identification because they easily diffuse through weak barriers like wallpaper, and could be used for early detection of mold growth in hidden cavities. This study identifies the production of anisole by seven toxigenic strains of Stachybotrys chartarum within a period of one week of growth on gypsum wallboard and ceiling tiles. These data could provide useful information for the future construction of a robust MVOC library for the early detection of this mold.

Fungal contamination in swine: a potential occupational health threat

Poor air quality in a pig-confinement building may potentially place farmers at higher health risk than other workers for exposure to airborne pollutants that may reach infectious levels. The aim of this study was to assess worker exposure to fungi in indoor environments in Portuguese swine buildings. Air samples from 7 swine farms were collected at a flow rate of 140 L/min, at 1 m height, onto malt extract agar supplemented with chloramphenicol (MEA). Surfaces samples of the same indoor sites were obtained by swabbing the surfaces. Samples from the floor covering were also collected from four of seven swine farms. All collected samples were incubated at 27°C for 5-7 days. After lab processing and incubation of obtained samples, quantitative colony-forming units (CFU)/m(3), CFU/cm(2), and CFU/g and qualitative results were determined with identification of isolated fungal species. Aspergillus versicolor was the most frequent species found in air (21%), followed by Scopulariopsis brevicaulis (17%) and Penicillium sp. (14%). Aspergillus versicolor was also the most frequent species noted on surfaces (26.6%), followed by Cladosporium sp. (22.4%) and Scopulariopsis brevicaulis (17.5%). Chrysosporium was the most frequently found genera in the new floor covering (38.5%), while Mucor was the most prevalent genera (25.1%) in used floor covering. Our findings corroborate a potential occupational health threat due to fungi exposure and suggest the need for a preventive strategy.

Fungal contamination of poultry litter: a public health problem

Although numerous studies have been conducted on microbial contaminants associated with various stages related to poultry and meat products processing, only a few reported on fungal contamination of poultry litter. The goals of this study were to (1) characterize litter fungal contamination and (2) report the incidence of keratinophilic and toxigenic fungi presence. Seven fresh and 14 aged litter samples were collected from 7 poultry farms. In addition, 27 air samples of 25 litters were also collected through impaction method, and after laboratory processing and incubation of collected samples, quantitative colony-forming units (CFU/m³) and qualitative results were obtained. Twelve different fungal species were detected in fresh litter and Penicillium was the most frequent genus found (59.9%), followed by Alternaria (17.8%), Cladosporium (7.1%), and Aspergillus (5.7%). With respect to aged litter, 19 different fungal species were detected, with Penicillium sp. the most frequently isolated (42.3%), followed by Scopulariopsis sp. (38.3%), Trichosporon sp. (8.8%), and Aspergillus sp. (5.5%). A significant positive correlation was found between litter fungal contamination (CFU/g) and air fungal contamination (CFU/m³). Litter fungal quantification and species identification have important implications in the evaluation of potential adverse health risks to exposed workers and animals. Spreading of poultry litter in agricultural fields is a potential public health concern, since keratinophilic (Scopulariopsis and Fusarium genus) as well as toxigenic fungi (Aspergillus, Fusarium, and Penicillium genus) were isolated.

Real and perceived risks for mycotoxin contamination in foods and feeds: challenges for food safety control

Mycotoxins are toxic compounds, produced by the secondary metabolism of toxigenic moulds in the Aspergillus, Alternaria, Claviceps, Fusarium, Penicillium and Stachybotrys genera occurring in food and feed commodities both pre- and post-harvest. Adverse human health effects from the consumption of mycotoxins have occurred for many centuries. When ingested, mycotoxins may cause a mycotoxicosis which can result in an acute or chronic disease episode. Chronic conditions have a much greater impact, numerically, on human health in general, and induce diverse and powerful toxic effects in test systems: some are carcinogenic, mutagenic, teratogenic, estrogenic, hemorrhagic, immunotoxic, nephrotoxic, hepatotoxic, dermotoxic and neurotoxic. Although mycotoxin contamination of agricultural products still occurs in the developed world, the application of modern agricultural practices and the presence of a legislatively regulated food processing and marketing system have greatly reduced mycotoxin exposure in these populations. However, in developing countries, where climatic and crop storage conditions are frequently conducive to fungal growth and mycotoxin production, much of the population relies on subsistence farming or on unregulated local markets. Therefore both producers and governmental control authorities are directing their efforts toward the implementation of a correct and reliable evaluation of the real status of contamination of a lot of food commodity and, consequently, of the impact of mycotoxins on human and animal health.

[Non allergic disorders associated with domestic moulds]

INTRODUCTION

Mouldy surfaces are encountered in up to 20 % of dwellings. Because this indoor air contamination is so widespread, respiratory physicians should be aware of its effects on health and especially of its impact on respiratory diseases.

BACKGROUND

The air contaminants within mouldy dwellings are very diverse. Therefore, a given heath effect cannot be attributed specifically to an individual contaminant. In the field of respiratory diseases, excluding asthma and allergy, long-term exposure to indoor moulds has been recognized as a risk factor for both ENT and bronchial symptoms. Hydrophilic moulds seem to have a larger health impact than other mould species. Among respiratory diseases, inhalation fever and, to a lesser extent, childhood respiratory infections are linked to exposure to moulds. In contrast, the relationship between exposure to indoor moulds and diseases such as sinusitis, mucous irritation syndrome, recurrent respiratory infections in adults, COPD and pulmonary haemorrhage has not been clearly established.

VIEWPOINT

There are still many scientific uncertainties in this field. However, the authorities are becoming more active in dealing with unhealthy buildings and encouraging research.

CONCLUSION

The health impact of mouldy dwellings represents a major public health issue. It needs incentives from institutions and financial support as well as the involvement of many specialists.

JEM Spotlight: Fungi, mycotoxins and microbial volatile organic compounds in mouldy interiors from water-damaged buildings

Concerns have been raised about exposure to mycotoxin producing fungi and the microbial volatile organic compounds (MVOCs) they produce in indoor environments. Therefore, the presence of fungi and mycotoxins was investigated in 99 samples (air, dust, wallpaper, mycelium or silicone) collected in the mouldy interiors of seven water-damaged buildings. In addition, volatile organic compounds (VOCs) were sampled. The mycotoxins were analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) (20 target mycotoxins) and quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). Morphological and molecular identifications of fungi were performed. Of the 99 samples analysed, the presence of one or more mycotoxins was shown in 62 samples by means of LC-MS/MS analysis. The mycotoxins found were mainly roquefortine C, chaetoglobosin A and sterigmatocystin but also roridin E, ochratoxin A, aflatoxin B(1) and aflatoxin B(2) were detected. Q-TOF-MS analysis elucidated the possible occurrence of another 42 different fungal metabolites. In general, the fungi identified matched well with the mycotoxins detected. The most common fungal species found were Penicillium chrysogenum, Aspergillus versicolor (group), Chaetomium spp. and Cladosporium spp. In addition, one hundred and seventeen (M)VOCs were identified, especially linear alkanes (C(9)-C(17)), aldehydes, aromatic compounds and monoterpenes.

Current state of the science: health effects and indoor environmental quality

Our understanding of the relationship between human health and the indoor environment continues to evolve. Previous research on health and indoor environments has tended to concentrate on discrete pollutant sources and exposures and on specific disease processes. Recently, efforts have been made to characterize more fully the complex interactions between the health of occupants and the interior spaces they inhabit. In this article we review recent advances in source characterization, exposure assessment, health effects associated with indoor exposures, and intervention research related to indoor environments. Advances in source characterization include a better understanding of how chemicals are transported and processed within spaces and the role that other factors such as lighting and building design may play in determining health. Efforts are under way to improve our ability to measure exposures, but this remains a challenge, particularly for biological agents. Researchers are also examining the effects of multiple exposures as well as the effects of exposures on vulnerable populations such as children and the elderly. In addition, a number of investigators are also studying the effects of modifying building design, materials, and operations on occupant health. Identification of research priorities should include input from building designers, operators, and the public health community.

Optimizing a GC-MS method for screening of Stachybotrys mycotoxins in indoor environments

Presence of Stachybotrys chartarum in indoor environments has been linked to building-associated disease, however, the causative agents are unknown. Verrucarol (VER) and trichodermol (TRID) are hydrolysis products of some major S. chartarum mycotoxins, i.e. macrocyclic trichothecenes and trichodermin. We optimized gas chromatography-mass spectrometry (GC-MS) methods for detecting VER and TRID in S. chartarum-contaminated indoor environmental samples. Heptafluorobutyryl derivatives of both VER and TRID exhibited little MS fragmentation and gave much higher detection sensitivity (sub-picogram injected onto the GC column), both in GC-MS and GC-MSMS, than trimethylsilyl derivatives. Optimal detection sensitivity and specificity was achieved by combining chemical ionization and negative ion (NICI) detection with MSMS. With this method, VER and TRID were detected in building materials colonized by S. chartarum and TRID was demonstrated in dust settled in the breathing zone in a house where an inner wall was colonized. In summary, we have shown that NICI-GC-MSMS can be used to demonstrate mycotoxins in house dust in S. chartarum-contaminated dwellings.

Mycotoxin identification in moldy dwellings

The objective of this study was to assess the level of macrocyclic trichothecenes (MCT), one of the most potent mycotoxins, on wall surfaces, floor dust and air samples from moldy dwellings. The study was based on an index group comprising 15 flooded dwellings contaminated by Stachybotrys chartarum or Chaetomium and a control group comprising nine dwellings without molds on visual inspection and mold sampling. Three samples were collected from each dwelling: a sample from the moldy wall, using a swab, a floor dust sample on a 0.5 m(2) surface with a cloth and an air sample using a pump comprising a 1 microm Teflon filter. The MCT level was measured using a monoclonal, antibody-based ELISA test. Compared with measurements performed in index dwellings, higher MCT values were measured on floor dust samples from moldy dwellings (P = 0.02). Samples from wall surfaces demonstrated nearly significant differences (P = 0.06). No significant differences were observed for air samples (P = 0.15), but some samples showed increased MCT levels. Significant correlations were observed between the levels measured on wall surfaces, floor dust and air samples (P = 0.02 to 0.05). In contrast, no correlation was observed between moldy surface and MCT levels. In conclusion, this paper reports for the first time direct evidence for the presence of MCT in moldy dwellings.

Development of a liquid chromatography/tandem mass spectrometry method for the simultaneous determination of 16 mycotoxins on cellulose filters and in fungal cultures

The development of a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of 16 mycotoxins possibly related to the 'Sick Building Syndrome' on filters and in fungal cultures is described. Fungi-surface sampling as regards the 'Sick Building Syndrome' preferably happens by scraping off fungal material and vacuuming onto cellulose filters. Therefore, these two media were used as samples. They were spiked with nivalenol, deoxynivalenol, zearalenone, diacetoxyscirpenol, T-2 toxin, verrucarol, verrucarin A, neosolaniol, sterigmatocystin, roridin A, ochratoxin A, aflatoxin B1, aflatoxin B2, aflatoxin G1 and aflatoxin G2, which can be produced by isolates from fungi-damaged buildings. Deepoxy-deoxynivalenol was used as internal standard. Samples were extracted with organic solvents and the different mycotoxins were separated by high-performance liquid chromatography (HPLC) using a C18 reversed-phase SunFire analytical column and a mobile phase of variable mixtures of ammonium acetate (10 mM) and sodium acetate (20 microM) in water (solvent A) and in methanol (solvent B). The samples were run on-line with a Micromass Quattro Micro triple quadrupole mass spectrometer in positive electrospray ionisation mode using multiple reaction monitoring (MRM). The detection limits of the procedure varied from 50 to 0.009 pg/microL for filter samples and from 75 to 0.04 pg/microL for fungal culture samples. As the method includes few and non-labourious sample treatment steps, it should allow for a high throughput of samples.

The vanilloid receptor as a putative target of diverse chemicals in multiple chemical sensitivity

The vanilloid receptor (TRPV1 or VR1), widely distributed in the central and peripheral nervous system, is activated by a broad range of chemicals similar to those implicated in Multiple Chemical Sensitivity (MCS) Syndrome. The vanilloid receptor is reportedly hyperresponsive in MCS and can increase nitric oxide levels and stimulate N-methyl-D-aspartate (NMDA) receptor activity, both of which are important features in the previously proposed central role of nitric oxide and NMDA receptors in MCS. Vanilloid receptor activity is markedly altered by multiple mechanisms, possibly providing an explanation for the increased activity in MCS and symptom masking by previous chemical exposure. Activation of this receptor by certain mycotoxins may account for some cases of sick building syndrome, a frequent precursor of MCS. Twelve types of evidence implicate the vanilloid receptor as the major target of chemicals, including volatile organic solvents (but not pesticides) in MCS.

Stachybotrydial, a potent inhibitor of fucosyltransferase and sialyltransferase

Elevated expression of fucosylated glycoconjugates and fucosyltransferases (Fuc-Ts) is found in various tumor cells and has been correlated with aspects of tumor progression such as cell adhesion and metastasis. Thus, fucosyltransferase inhibitors are potentially useful as anti-tumor agents. In the present study, three known spirocyclic drimanes (1, 2, and 3) were isolated from the culture broth of the fungus Stachybotrys cylindrospora. Compound 1 (stachybotrydial) exhibits potent inhibitory activity against alpha1,3-fucosyltransferase (Fuc-TV) during screening, while compounds 2 and 3 show no such inhibitory activity. Kinetic analysis indicates that compound 1 is an uncompetitive inhibitor with respect to GDP-fucose and a noncompetitive inhibitor with respect to N-acetyllactosamine with Ki values of 10.7 and 9.7 microM, respectively. In addition, all three compounds also possess inhibitory activity against sialyltransferase (ST) but not against beta1,4-galactosyltransferase. These observations provide novel chemical structure information that will help in the design of novel Fuc-T and ST inhibitors.

Mycotoxins as harmful indoor air contaminants

Fungal metabolites (mycotoxins) that pose a health hazard to humans and animals have long been known to be associated with mold-contaminated food and feed. In recent times, concerns have been raised about exposures to mycotoxin-producing fungi in indoor environments, e.g., damp homes and buildings. The principal mycotoxins that contaminate food and feed (alfatoxins, fumonisins, ochratoxin A, deoxynivalenol, zearalenone) are rarely if ever found in indoor environments, but their toxicological properties provide an insight into the difficulties of assessing the health effects of related mycotoxins produced by indoor molds. Although the Penicillium and Aspergillus genera of fungi are major contaminants of both food and feed products and damp buildings, the particular species and hence the array of mycotoxins are quite different in these environments. The mycotoxins of these indoor species and less common mycotoxins from Stachybotrys and Chaetomium fungi are discussed in terms of their health effects and the need for relevant biomarkers and long-term chronic exposure studies.