Secondary metabolites from Eurotium species, Aspergillus calidoustus and A. insuetus common in Canadian homes with a review of their chemistry and biological activities

Secondary Metabolites from the Genus Eurotium and Their Biological Activities

Eurotium is the teleomorph genus associated with the section Aspergillus. Eurotium comprises approximately 20 species, which are widely distributed in nature and human environments. Eurotium is usually the key microorganism for the fermentation of traditional food, such as Fuzhuan brick tea, Liupao tea, Meju, and Karebushi; thus, Eurotium is an important fungus in the food industry. Eurotium has been extensively studied because it contains a series of interesting, structurally diverse, and biologically important secondary metabolites, including anthraquinones, benzaldehyde derivatives, and indol diketopiperazine alkaloids. These secondary metabolites have shown multiple biological activities, including antioxidative, antimicrobial, cytotoxic, antitumor, insecticidal, antimalarial, and anti-inflammatory activities. This study presents an up-to-date review of the phytochemistry and biological activities of all Eurotium species. This review will provide recent advances on the secondary metabolites and their bioactivities in the genus Eurotium for the first time and serve as a database for future research and drug development from the genus Eurotium.

Metabolomic profiles of the liquid state fermentation in co-culture of Eurotium amstelodami and Bacillus licheniformis

As an important source of new drug molecules, secondary metabolites (SMs) produced by microorganisms possess important biological activities, such as antibacterial, anti-inflammatory, and hypoglycemic effects. However, the true potential of microbial synthesis of SMs has not been fully elucidated as the SM gene clusters remain silent under laboratory culture conditions. Herein, we evaluated the inhibitory effect of Staphylococcus aureus by co-culture of Eurotium amstelodami and three Bacillus species, including Bacillus licheniformis, Bacillus subtilis, and Bacillus amyloliquefaciens. In addition, a non-target approach based on ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOF-MS) was used to detect differences in extracellular and intracellular metabolites. Notably, the co-culture of E. amstelodami and Bacillus spices significantly improved the inhibitory effect against S. aureus, with the combination of E. amstelodami and B. licheniformis showing best performance. Metabolomics data further revealed that the abundant SMs, such as Nummularine B, Lucidenic acid E2, Elatoside G, Aspergillic acid, 4-Hydroxycyclohexylcarboxylic acid, Copaene, and Pipecolic acid were significantly enhanced in co-culture. Intracellularly, the differential metabolites were involved in the metabolism of amino acids, nucleic acids, and glycerophospholipid. Overall, this work demonstrates that the co-culture strategy is beneficial for inducing biosynthesis of active metabolites in E. amstelodami and B. licheniformis.

Bispyrrolidinoindoline Epi(poly)thiodioxopiperazines (BPI-ETPs) and Simplified Mimetics: Structural Characterization, Bioactivities, and Total Synthesis

Within the 2,5-dioxopiperazine-containing natural products generated by “head-to-tail” cyclization of peptides, those derived from tryptophan allow further structural diversification due to the rich chemical reactivity of the indole heterocycle, which can generate tetracyclic fragments of hexahydropyrrolo[2,3-b]indole or pyrrolidinoindoline skeleton fused to the 2,5-dioxopiperazine. Even more complex are the dimeric bispyrrolidinoindoline epi(poly)thiodioxopiperazines (BPI-ETPs), since they feature transannular (poly)sulfide bridges connecting C3 and C6 of their 2,5-dioxopiperazine rings. Homo- and heterodimers composed of diastereomeric epi(poly)thiodioxopiperazines increase the complexity of the family. Furthermore, putative biogenetically generated downstream metabolites with C11 and C11’-hydroxylated cores, as well as deoxygenated and/or oxidized side chain counterparts, have also been described. The isolation of these complex polycyclic tryptophan-derived alkaloids from the classical sources, their structural characterization, the description of the relevant biological activities and putative biogenetic routes, and the synthetic efforts to generate and confirm their structures and also to prepare and further evaluate structurally simple analogs will be reported.

Structures and Biological Activities of Alkaloids Produced by Mushrooms, a Fungal Subgroup

Alkaloids are a wide family of basic N-containing natural products, whose research has revealed bioactive compounds of pharmacological interest. Studies on these compounds have focused more attention on those produced by plants, although other types of organisms have also been proven to synthesize bioactive alkaloids, such as animals, marine organisms, bacteria, and fungi. This review covers the findings of the last 20 years (2002–2022) related to the isolation, structures, and biological activities of the alkaloids produced by mushrooms, a fungal subgroup, and their potential to develop drugs and agrochemicals. In some cases, the synthesis of the reviewed compounds and structure−activity relationship studies have been described.

Chemical synthesis in competition with global genome mining and heterologous expression for the preparation of dimeric tryptophan-derived 2,5-dioxopiperazines

Covering: up to the end of 2021Within the 2,5-dioxopiperazines-containing natural products, those generated from tryptophan allow further structural diversification due to the rich chemical reactivity of the indole heterocycle. The great variety of natural products, ranging from simple dimeric bispyrrolidinoindoline dioxopiperazines and tryptophan-derived dioxopiperazine/pyrrolidinoindoline dioxopiperazine analogs to complex polycyclic downstream metabolites containing transannular connections between the subunits, will be covered. These natural products are constructed by Nature using hybrid polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) assembly lines. Mining of microbial genome sequences has more recently allowed the study of the metabolic routes and the discovery of their hidden biosynthetic potential. The competition (ideally, also the combined efforts) between their isolation from the cultures of the producing microorganisms after global genome mining and heterologous expression and the synthetic campaigns, has more recently allowed the successful generation and structural confirmation of these natural products. Their biological activities as well as their proposed biogenetic routes and computational studies on biogenesis will also be covered.

Endophytic Fungus from Opuntia ficus-indica: A Source of Potential Bioactive Antimicrobial Compounds against Multidrug-Resistant Bacteria

Endophytic Aspergillus species represent an inexhaustible source for many medicinally important secondary metabolites. The current study isolated the endophytic Aspergillus niger (OL519514) fungus from Opuntia ficus-indica fruit peels. The antibacterial activities were reported for both Aspergillus species and Opuntia ficus-indica fruit peel extract. Extraction of the endophytic fungal metabolites using ethyl acetate and fractionation was performed, yielding dihydroauroglaucin (C1), isotetrahydroauroglaucin (C2), and cristatumin B (C3). Resistant bacterial strains were used to investigate the efficiency of the total fungal ethyl acetate extract (FEA) and the isolated compounds. FEA showed promising wide spectrum activity. (C3) showed excellent activity against selected Gram-negative resistant bacteria; However, (C2) exhibited tremendous activity against the tested Gram-positive resistant strains; conversely, (C1) possessed the lowest antibacterial activity compared to the two other compounds. An in silico virtual molecular docking demonstrated that cristatumin B was the most active antimicrobial compound against the selected protein targets. In conclusion, the active metabolites newly isolated from the endophytic fungus Aspergillus niger (OL519514) and present in plants' waste can be a promising antimicrobial agent against multidrug-resistant bacteria.

In silico analyses of maleidride biosynthetic gene clusters

Maleidrides are a family of structurally related fungal natural products, many of which possess diverse, potent bioactivities. Previous identification of several maleidride biosynthetic gene clusters, and subsequent experimental work, has determined the 'core' set of genes required to construct the characteristic medium-sized alicyclic ring with maleic anhydride moieties. Through genome mining, this work has used these core genes to discover ten entirely novel putative maleidride biosynthetic gene clusters, amongst both publicly available genomes, and encoded within the genome of the previously un-sequenced epiheveadride producer Wicklowia aquatica CBS 125634. We have undertaken phylogenetic analyses and comparative bioinformatics on all known and putative maleidride biosynthetic gene clusters to gain further insights regarding these unique biosynthetic pathways.

A nonadride derivative from the marine-derived fungus Aspergillus chevalieri PSU-AMF79

One new nonadride enantiomer, ent-epiheveadride, along with five known dioxopiperazine derivatives were isolated from the marine-derived fungus Aspergillus chevalieri PSU-AMF79. Their structures were identified by extensive spectroscopic analysis. The absolute configuration of ent-epiheveadride was determined by comparison of the specific rotation and electronic circular dichroism data with those of related known compounds. It exhibited antifungal activity against Cryptococcus neoformans ATCC90113 flucytosine-resistant and Candida albicans NCPF3153 with the MIC values of 128 and 200 µg/mL, respectively. In addition, the known L-alanyl-L-tryptophan anhydride displayed TMEM16A inhibitory activity with 65.0% inhibition at a concentration of 5 µg/mL.

Genome Mining and Analysis of PKS Genes in Eurotium cristatum E1 Isolated from Fuzhuan Brick Tea

Eurotium cristatum as the dominant fungi species of Fuzhuan brick tea in China, can produce multitudinous secondary metabolites (SMs) with various bioactivities. Polyketides are a very important class of SMs found in E. cristatum and have gained extensive attention in recent years due to their remarkable diversity of structures and multiple functions. Therefore, it is necessary to explore the polyketides produced by E. cristatum at the genomic level to enhance its application value. In this paper, 12 polyketide synthase (PKS) genes were found in the whole genome of E. cristatum E1 isolated from Fuzhuan brick tea. In addition, the qRT-PCR results further demonstrated that these genes were expressed. Moreover, metabolic analysis demonstrated E. cristatum E1 can produce a variety of polyketides, including citreorosein, emodin, physcion, isoaspergin, dihydroauroglaucin, iso-dihydroauroglaucin, aspergin, flavoglaucin and auroglaucin. Furthermore, based on genomic analysis, the putative secondary metabolites clusters for emodin and flavoglaucin were proposed. The results reported here will lay a good basis for systematically mining SMs resources of E. cristatum and broadening its application fields.

Microbial Depolymerization of Epoxy Resins: A Novel Approach to a Complex Challenge

The objective of this project is evaluating the potential of microbes (fungi and bacteria) for the depolymerization of epoxy, aiming at the development of a circular management of natural resources for epoxy in a long-term prospective. For depolymerization, epoxy samples were incubated for 1, 3, 6 and 9 months in soil microcosms inoculated with Ganoderma adspersum. Contact angle data revealed a reduction in the hydrophobicity induced by the fungus. Environmental scanning electron microscopy on epoxy samples incubated for more than 3 years in microbiological water revealed abundant microbiota. This comprised microbes of different sizes and shapes. The fungi Trichoderma harzianum and Aspergillus calidoustus, as well as the bacteria Variovorax sp. and Methyloversatilis discipulorum, were isolated from this environment. Altogether, these results suggest that microbes are able to colonize epoxy surfaces and, most probably, also partially depolymerize them. This could open promising opportunities for the study of new metabolisms potentially able depolymerize epoxy materials.

Dynamic Evolution and Correlation between Metabolites and Microorganisms during Manufacturing Process and Storage of Fu Brick Tea

Fu brick tea (FBT) is one of the major brands of dark tea. Microbial fermentation is considered the key step in the development of the special characteristics of FBT. The systemic corelationship of the microbiome and metabolomics during manufacture of Fu brick tea is not fully understood. In this study, we comprehensively explored the microbiome and metabolite dynamic evolution during the FBT manufacturing processes, and revealed decisive factors for the quality and safety of FBT based on the grouped methods of metabolomics combined with biochemical measurements, microbiome sequencing combined with quantitative polymerase chain reaction (PCR), and multiplex analysis. Both the microbiome and quantitative PCR showed that fungi displayed concentrated distribution characteristics in the primary dark tea samples, while bacterial richness increased during the flowering processes and ripening period. All microorganism species, as well as dominant fungi and bacteria, were identified in the distinct processes periods. A total of 178 metabolites were identified, and 34 of them were characterized as critical metabolites responsible for metabolic changes caused by the corresponding processes. Metabolic analysis showed that most metabolites were decreased during the FBT manufacturing processes, with the exception of gallic acid. Multivariate analysis verified that the critical metabolites were correlated with specific dominant microbial species. All the top fungal species except unclassified_g_ Aspergillus showed positive correlations with six critical metabolites (L-The, epigallocatechin (EGC), Gln, tea polyphenol (TP), tea polysaccharides (TPs) and caffeine). Five of the top bacteria species (Cronobacter, Klebsiella, Pantoea, Pluralibacter, and unclassified_ f_Entero-bacteriaceae) showed positive correlations with epigallocatechins and tea polyphenols, while the other 11 top bacterial species correlated negatively with all the critical metabolites. The content of amino acids, tea polyphenols, tea polysaccharides, and flavonoids was reduced during microbial fermentation. In conclusion, our results reveal that microbial composition is the critical factor in changing the metabolic profile of FBT. This discovery provides a theoretical basis for improving the quality of FBT and enhancing its safety.

Therapeutic Potential of Neoechinulins and Their Derivatives: An Overview of the Molecular Mechanisms Behind Pharmacological Activities

Neoechinulins are diketopiperazine type indole alkaloids that demonstrate radical scavenging, anti-inflammatory, antiviral, anti-neurodegenerative, neurotrophic factor-like, anticancer, pro-apoptotic, and anti-apoptotic properties. An array of neoechinulins such as neoechinulins A-E, isoechinulins A-C, cryptoechunilin have been isolated from various fungal sources like Aspergillus sp., Xylaria euglossa, Eurotium cristatum, Microsporum sp., etc. Besides, neoechinulin derivatives or stereoisomers were also obtained from diverse non-fungal sources viz. Tinospora sagittata, Opuntia dillenii, Cyrtomium fortunei, Cannabis sativa, and so on. The main purpose of this review is to provide update information on neoechinulins and their analogues about the molecular mechanisms of the pharmacological action and possible future research. The recent data from this review can be used to create a basis for the discovery of new neoechinulin-based drugs and their analogues in the near future. The online databases PubMed, Science and Google scholar were researched for the selection and collection of data from the available literature on neoechinulins, their natural sources and their pharmacological properties. The published books on this topic were also analysed. In vitro and in vivo assays have established the potential of neoechinulin A as a promising anticancer and anti-neuroinflammatory lead molecule. Neoechinulin B was also identified as a potential antiviral drug against hepatitis C virus. Toxicological and clinical trials are needed in the future to improve the phyto-pharmacological profile of neoquinolines. From the analysis of the literature, we found that neoechinulins and their derivatives have special biological potential. Although some modern pharmacological analyzes have highlighted the molecular mechanisms of action and some signalling pathways, the correlation between these phytoconstituents and pharmacological activities must be validated in the future by preclinical toxicological and clinical studies.

Genetic and Histopathological Alterations in Caco-2 and HuH-7 Cells Treated with Secondary Metabolites of Marine fungi

The present work aimed to study the activity of naturally derived fungal secondary metabolites as anticancer agents concerning their cytotoxicity, apoptotic, genetic, and histopathological profile. It was noticed that Aspergillus terreus, Aspergillus flavus, and Aspergillus fumigatus induced variable toxic potential that was cell type, secondary metabolite type, and concentration dependent. Human colonic adenocarcinoma cells (Caco-2) showed less sensitivity than hepatocyte-derived cellular carcinoma cells (HuH-7), and in turn, the half-maximal inhibitory concentration (IC₅₀) was variable. Also, the apoptotic potential of Aspergillus species-derived fungal secondary metabolites was proven via detection of up-regulated pro-apoptotic genes and down-regulation of anti-apoptotic genes. The expression level was cell type dependent. Concurrently, apoptotic profile was accompanied with cellular DNA accumulation at the G2/M phase, as well as an elevation in Pre-G1 phase but not during G0/G1 and S phases. Also, there were characteristic apoptotic features of treated cells presented as abnormal intra-nuclear eosinophilic structures, dead cells with mixed euchromatin and heterochromatin, ruptured cell membranes, apoptotic cells with irregular cellular and nuclear membranes, as well as peripheral chromatin condensation. It can be concluded that Aspergillus secondary metabolites are promising agents that can be used as supplementary agents to the currently applied anti-cancer drug regimen.

Growth characterization and predictive behavior of Eurotium species in a feedstuff matrix

Animal feeds are characterized by low water activity values. Nevertheless, fungal contamination with Eurotium species are quite common, causing nutritional depletion, spoilage and economic losses. The aim of this work was to assess Eurotium amstelodami, E. chevalieri, E. repens and E. rubrum growth in a feed matrix at different conditions of water activity (0.71-0.97) and temperature (5, 15, 25, 30 and 37°C). It was found that Eurotium species are able to grow in a wide range of water activity and temperature in a short period of time (7 days) and faster than in synthetic media. Rosso and probabilistic models were applied in order to determine the limiting and optimum growth conditions as well as growth probability at certain combinations of environmental factors. Both models provided an accurate fit to the cardinal parameters and good performance for growth/no growth cases. This is the first report assessing the growth parameters of Eurotium species directly in animal feed. Data obtained in the present study is useful to predict and avoid Eurotium species growth in animal feed.

Guirlanda C, A. F. Moura M. Use of the Versatility of Fungal Metabolism to Meet Modern Demands for Healthy Aging, Functional Foods, and Sustainability

Aging-associated, non-transmissible chronic diseases (NTCD) such as cancer, dyslipidemia, and neurodegenerative disorders have been challenged through several strategies including the consumption of healthy foods and the development of new drugs for existing diseases. Consumer health consciousness is guiding market trends toward the development of additives and nutraceutical products of natural origin. Fungi produce several metabolites with bioactivity against NTCD as well as pigments, dyes, antioxidants, polysaccharides, and enzymes that can be explored as substitutes for synthetic food additives. Research in this area has increased the yields of metabolites for industrial applications through improving fermentation conditions, application of metabolic engineering techniques, and fungal genetic manipulation. Several modern hyphenated techniques have impressively increased the rate of research in this area, enabling the analysis of a large number of species and fermentative conditions. This review thus focuses on summarizing the nutritional, pharmacological, and economic importance of fungi and their metabolites resulting from applications in the aforementioned areas, examples of modern techniques for optimizing the production of fungi and their metabolites, and methodologies for the identification and analysis of these compounds.

Biological control of mites by xerophile Eurotium species isolated from the surface of dry cured ham and dry beef cecina

Some meat dry products, including dry cured ham and dry beef cecina, are cured in cellars at moderately cold temperature allowing the growth of a lawn of fungi on their surface. During the curing process, frequently these products became contaminated with fungivore mites of the Acaridae family that feed on fungal mycelium and spores.

AIMS

The aim of this article is to study the possible biological control of mites by fungi that form part of the normal microbiota of these meat products.

METHODS AND RESULTS

Some yellow/orange pigmented fungi growing on the ham surface decreased the proliferation of mites; therefore, we isolated from ham and cecina xerophilic yellow/orange coloured fungal strains that were identified as members of the genus Eurotium (recently reclassified as Aspergillus section Aspergillus). Using molecular genetic tools, we have identified 158 strains as Eurotium rubrum (Aspergillus ruber), Eurotium repens (Aspergillus pseudoglaucus) and Eurotium chevalieri (Aspergillus chevalieri). Two strains, E. rubrum C47 and E. rubrum C49, showed strong miticidal activity. The toxic compound(s) are associated with the formation of cleistothecia. In synchronized mite development experiments, we observed that all stages of the mite lifecycle were inhibited by the E. rubrum C47 strain. In addition, we searched for miticidal activity in 13 culture collection Eurotium strains isolated from different habitats, and found that only one, Eurotium cristatum NRRL 4222 (Aspergillus cristatus) has a strong miticidal activity.

CONCLUSIONS

These fungal strains have proliferated on the surface of ham and cecina for decades, and possibly have acquired miticidal activity as a resistance mechanism against fungivores.

SIGNIFICANCE AND IMPACT OF THE STUDY

Biological control of infecting mites by favouring growth of E. rubrun C47, in place of the normal mixed population of Aspergillus and Penicillium, is an attractive approach to control mite infestations.

Characterization and proliferation capacity of potentially pathogenic fungi in marine and freshwater fish commercial feeds

In the aquaculture industry, the selection and quality of feed are highly relevant because their integrity and management have an impact on the health and development of organisms. In general, feeds contamination depends on storage conditions and formulation. Furthermore, it has been recognized that filamentous fungi are among the most important contaminating agent in formulated feeds. Therefore, the purpose of this research was to identify saprophytic fungi capable of proliferating in commercial feeds, as well as determining their prevalence, extracellular enzymes profile, ability to assimilate carbon sources, and finally their ability to produce aflatoxins. In order to do that, twenty-two fungi were isolated from commercial fish feeds. After, the species Aspergillus chevalieri, A. cristatus, A. sydowii, A. versicolor, A. flavus, A. creber, and Lichtheimia ramosa were identified. These fungi were able to produce extracellular enzymes, such as phosphatases, esterases, proteases, β-glucosidase, and N-acetyl-β-glucosaminidase. The isolated fungi showed no selective behavior in the assimilation of the different carbon sources, showing a strong metabolic diversity. Prevalence percentages above 85% were recorded. Among all fungi studied, A. flavus M3-C1 had the highest production of aflatoxins when this strain was inoculated directly in the feeds (295 ppb). The aflatoxin production by this strain under the experimental setting is above the permitted levels, and it has been established that high levels of aflatoxins in feeds can cause alterations in fish growth as well as the development of cancerous tumors in the liver, in addition to enhancing mortality.

Purification, characterization, and hypoglycemic properties of eurocristatine from Eurotium cristatum spores in Fuzhuan brick tea

Fuzhuan brick tea (FBT) is a Chinese dark tea that is famous for its significant health benefits, in which Eurotium cristatum (E. cristatum) strains play a vital role in its postfermentation process. In this study, eurocristatine with hypoglycemic activity was discovered for the first time and purified from the spores of E. cristatum growing in FBT. Eurocristatine (98%) was obtained by D-101 macroporous resin-based column chromatography and preparative high performance liquid chromatography (HPLC) with a C18 column as the stationary phase and 35% acetonitrile in ultrapure water as the mobile phase. Hypoglycemic activity in a Hep-G2 cell hypoglycemic model was used as a screening indicator during purification. The chemical structure of eurocristatine was characterized by ESI/MS, 1H NMR and 13C NMR analyses. The antidiabetic effects of eurocristatine were verified in high-fat diet/streptozocin-induced type 2 diabetes mellitus (T2DM) rats. The results showed that eurocristatine significantly reduced fasting blood glucose. Our study demonstrated that eurocristatine, as a newly discovered hypoglycemic active substance, could be considered a potential candidate for the treatment of diabetes and its complications.

Chemical Composition of Aspergillus creber Extract and Evaluation of its Antimicrobial and Antioxidant Activities

Among the species belonging to the Aspergillus section Versicolores, Aspergillus creber has been poorly studied and still unexplored for its biological activities. The present study was undertaken to analyze A. creber extract and to evaluate its in vitro antimicrobial and anti-oxidant activities. UHPLC-MS/MS analysis of A. creber extract allowed the characterization of five known fungal metabolites including: asperlactone, emodin, sterigmatocystin, deoxybrevianamide E, and norsolorinic acid. The highest antimicrobial activity was displayed against Candida albicans, with a mean strongest inhibition zone of 20.6 ± 0.8 mm, followed by Gram-positive drug-resistant bacteria. The MIC values of A. creber extract varied from 0.325 mg/ml to 5 mg/ml. A. creber extract was shown a potent antioxidant activity and a high level of phenolic compounds by recording 89.28% scavenging effect for DPPH free radical, 92.93% in ABTS assay, and 85.76 mg gallic acid equivalents/g extract in Folin-Ciocalteu assay. To our knowledge, this is the first study concerning biological and chemical activities of A. creber species. Based on the obtained results, A. creber could be a promising source of natural antimicrobial and antioxidant compounds.

Screening Mold Colonies by Using Two Toxicity Assays Revealed Indoor Strains of Aspergillus calidoustus Producing Ophiobolins G and K

The occurrence and toxin production of the opportunistic pathogen Aspergillus calidoustus in Finnish buildings is not well documented in the literature. We tracked and identified four A. calidoustus colonies cultivated from indoor settled dusts and revealed the biological activities of crude biomass extracts. The toxic substances were identified as 6-epi-ophiobolin K, ophiobolin K, and ophiobolin G by high-performance liquid chromatography–mass spectrometry (HPLC-MS) based on chromatographic and mass spectrometry data (MS and MS/MS) on the crude extract of A. calidoustus strain MH34. A total of 29 fungal colonies collected from settled dust in an office room reported for indoor-air-related illnesses were screened for toxins that inhibited boar sperm motility in the BSMI (boar sperm motility inhibiting) assay and cell proliferation in the ICP (inhibition of cell proliferation) assays with PK-15 cells. Out of the 27 colonies tested as toxic, 12 colonies exhibiting conidiophores representative of the genera Chaetomium, Penicillium, and Paecilomyces were excluded from the study, while 13 colonies exhibited Aspergillus-like conidiophores. Biomass suspensions of these colonies were divided into two categories: Category 1 colonies (n = 4), toxic in the BSMI assay and the ICP assays, emitted blue fluorescence and grew at 37 °C; Category 2 colonies (n = 9), only toxic in the ICP assay, emitted orange fluorescence and exhibited limited or no growth at 37 °C. Colonies in Category 1 were pure-cultured, and the strains were named as MH4, MH21, MH34, MH36. Strain MH34 was identified as A. calidoustus by the internal transcribed spacer (ITS) sequences. Ethanol-soluble dry substances extracted from the biomass of the pure cultures exhibited a toxicological profile in the BSMI assay, SMID (sperm membrane integrity damage) assay, and ICP assay similar to that exhibited by pure ophiobolin A. Overall, the viable conidia of A. calidoustus in indoor settled dusts deserve attention when potentially hazardous mold species are monitored.

Bio-Guided Fractionation of Prenylated Benzaldehyde Derivatives as Potent Antimicrobial and Antibiofilm from Ammi majus L. Fruits-Associated Aspergillus amstelodami

Ammi majus L.; Family Apiaceae; is a plant indigenous to Egypt. Its fruits contain bioactive compounds such as furanocoumarins and flavonoids of important biological activities. An endophytic fungus was isolated from the fruits and identified as Aspergillus amstelodami (MK215708) by morphology, microscopical characterization, and molecular identification. To our knowledge this is the first time an endophytic fungus has been isolated from the fruits. The antimicrobial activity of the Ammi majus ethanol fruits extract (AME) and fungal ethyl acetate extract (FEA) were investigated, where the FEA showed higher antimicrobial activity, against all the tested standard strains. Phytochemical investigation of the FEA extract yielded five prenylated benzaldehyde derivative compounds isolated for the first time from this species: Dihydroauroglaucin (1), tetrahydroauroglaucin (2), 2-(3,6-dihydroxyhepta-1,4-dien-1-yl)-3,6-dihydroxy-5-(dimethylallyl)benzaldehyde (3), isotetrahydroauroglaucin )4), and flavoglaucin (5). Structure elucidation was carried out using (1H- and 13C-NMR). Fractions and the major isolated compound 1 were evaluated for their antimicrobial and antibiofilm activity. Compound 1 showed high antimicrobial activity against Escherichia coli with minimum inhibitory concentration (MIC) = 1.95 µg/mL, Streptococcus mutans (MIC = 1.95 µg/mL), and Staphylococcus aureus (MIC = 3.9 µg/mL). It exhibited high antibiofilm activity with minimum biofilm inhibitory concentration (MBIC) = 7.81 µg/mL against Staphylococcus aureus and Escherichia coli biofilms and MBIC = 15.63 µg/mL against Streptococcus mutans and Candida albicans and moderate activity (MBIC = 31.25 µg/mL) against Pseudomonas aeruginosa biofilm. This reveals that dihydroauroglaucin, a prenylated benzaldehyde derivative, has a broad spectrum antimicrobial activity. In conclusion, it was observed that the MICs of the FEA are much lower than that of the AME against all susceptible strains, confirming that the antimicrobial activity of Ammi majus may be due to the ability of its endophytic fungi to produce effective secondary metabolites.

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

Chemical investigation of an undescribed Australian fungus, Aspergillus nanangensis, led to the identification of the nanangenines - a family of seven new and three previously reported drimane sesquiterpenoids. The structures of the nanangenines were elucidated by detailed spectroscopic analysis supported by single crystal X-ray diffraction studies. The compounds were assayed for in vitro activity against bacteria, fungi, mammalian cells and plants. Bioinformatics analysis, including comparative analysis with other acyl drimenol-producing Aspergilli, led to the identification of a putative nanangenine biosynthetic gene cluster that corresponds to the proposed biosynthetic pathway for nanangenines.

Zebrafish-Based Discovery of Antiseizure Compounds from the North Sea: Isoquinoline Alkaloids TMC-120A and TMC-120B

There is a high need for the development of new and improved antiseizure drugs (ASDs) to treat epilepsy. Despite the potential of marine natural products (MNPs), the EU marine biodiscovery consortium PharmaSea has made the only effort to date to perform ASD discovery based on large-scale screening of MNPs. To this end, the embryonic zebrafish photomotor response assay and the larval zebrafish pentylenetetrazole (PTZ) model were used to screen MNP extracts for neuroactivity and antiseizure activity, respectively. Here we report the identification of the two known isoquinoline alkaloids TMC-120A and TMC-120B as novel antiseizure compounds, which were isolated by bioactivity-guided purification from the marine-derived fungus Aspergillus insuetus. TMC-120A and TMC-120B were observed to significantly lower PTZ-induced seizures and epileptiform brain activity in the larval zebrafish PTZ seizure model. In addition, their structural analogues TMC-120C, penicisochroman G, and ustusorane B were isolated and also significantly lowered PTZ-induced seizures. Finally, TMC-120A and TMC-120B were investigated in a mouse model of drug-resistant focal seizures. Compound treatment significantly shortened the seizure duration, thereby confirming their antiseizure activity. These data underscore the possibility to translate findings in zebrafish to mice in the field of epilepsy and the potential of the marine environment for ASD discovery.

Induction of pigment production through media composition, abiotic and biotic factors in two filamentous fungi

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Pigment production and accumulation is dependent of high C:N ratios in F. oxysporum and A. chevaleri.

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Red pigment content of F. oxysporum in terms of Absorbance units per gram of biomass increased in 191% through use of blue light. Different light wavelengths stimulate synthesis of additional pigments in A. chevalieri with highest accumulation in red and UV-light.

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Stimulation of pigment production in co-culture is species – specific, being only accomplished in A. chevalieri. With a rise higher that 500% of a pigment obtained in green light.

In addition to plant-derived, fungal pigments have become an alternative in respect to synthetic ones. Besides Monascus sp., several pigment-producing fungi do not have culture conditions well-established yet. In this research, media composition, light wavelength and co-culture were evaluated, results were reported in Absorbance Units per gram of biomass (AU/Bgr). For Fusarium oxysporum a C:N ratio above 7 was advantageous, using both complex and defined media; blue LED light increased the AU/Bgr value from 18013 to 344; co-culture did not enhance pigment production. In Aspergillus chevalieri a high C:N ratio with glucose as carbon source was ideal. When exposing cultures to light, UV and red light gave the highest pigmentation; moreover, differential UV-VIS spectra in all wavelengths suggested production of additional pigments. Particularly a pigment observed when cultured in green light was also found in co-culture with yeast and there was an improvement of AU/Bgr value of 52549%. This is the first report regarding light effect and co-culture for these fungi, as well as C:N ratio for A. chevalieri.

Asperflavin, an Anti-Inflammatory Compound Produced by a Marine-Derived Fungus, Eurotium amstelodami

In the present study, 16 marine-derived fungi were isolated from four types of marine materials including float, algae, animals and drift woods along with the coast of Jeju Island, Korea and evaluated for anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated RAW 24.7 cells. The broth and mycelium extracts from the 16 fungi were prepared and the broth extract (BE) of Eurotium amstelodami (015-2) inhibited nitric oxide (NO) production in LPS-stimulated RAW 264.7 cells without cytotoxicity. By further bioassay-guided isolation, three compounds including asperflavin, neoechinulin A and preechinulin were successfully isolated from the BE of E. amstelodami. It was revealed that asperflavin showed no cytotoxicity up to 200 μM and significantly inhibited LPS-induced NO and PGE2 production in a dose-dependent manner. In the western blot results, asperflavin suppressed only inducible NOS (iNOS), but COX-2 were slightly down-regulated. Asperflavin was also observed to inhibit the production of pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6. In conclusion, this study reports a potential use of asperflavin isolated from a marine fungus, E. amstelodami as an anti-inflammatory agent via suppression of iNOS and pro-inflammatory cytokines as well as no cytotoxicity.

Aspergillus subgenus Polypaecilum from the built environment

Xerophilic fungi, especially Aspergillus species, are prevalent in the built environment. In this study, we employed a combined culture-independent (454-pyrosequencing) and culture-dependent (dilution-to-extinction) approach to investigate the mycobiota of indoor dust collected from 93 buildings in 12 countries worldwide. High and low water activity (aw) media were used to capture mesophile and xerophile biodiversity, resulting in the isolation of approximately 9 000 strains. Among these, 340 strains representing seven putative species in Aspergillus subgenus Polypaecilum were isolated, mostly from lowered aw media, and tentatively identified based on colony morphology and internal transcribed spacer rDNA region (ITS) barcodes. Further morphological study and phylogenetic analyses using sequences of ITS, β-tubulin (BenA), calmodulin (CaM), RNA polymerase II second largest subunit (RPB2), DNA topoisomerase 1 (TOP1), and a pre-mRNA processing protein homolog (TSR1) confirmed the isolation of seven species of subgenus Polypaecilum, including five novel species: A. baarnensis, A. keratitidis, A. kalimae sp. nov., A. noonimiae sp. nov., A. thailandensis sp. nov., A. waynelawii sp. nov., and A. whitfieldii sp. nov. Pyrosequencing detected six of the seven species isolated from house dust, as well as one additional species absent from the cultures isolated, and three clades representing potentially undescribed species. Species were typically found in house dust from subtropical and tropical climates, often in close proximity to the ocean or sea. The presence of subgenus Polypaecilum, a recently described clade of xerophilic/xerotolerant, halotolerant/halophilic, and potentially zoopathogenic species, within the built environment is noteworthy.

Fungal community succession and major components change during manufacturing process of Fu brick tea

Fu brick tea is a unique post-fermented tea product which is fermented with microorganism during the manufacturing process. Metabolic analysis showed that most metabolites content were decreased during the manufacturing process of Fu brick tea, except GA (gallic acid). Illumina MiSeq sequencing of ITS gene amplicons was applied to analyze the fungal community succession. The genera Aspergillus, Cyberlindnera and Candida were predominant at the early stage of manufacturing process (from "primary dark tea" to "fermentation for 3 days"), but after the stage of "fermentation for 3 days" only Aspergillus was still dominated, and maintain a relatively constant until to the end of manufacturing process. The effects of metabolites on the structure of the fungal community were analyzed by redundancy analysis (RDA) and variation partitioning analysis (VPA). The results indicated that GCG (gallocatechin gallate), EGCG (epigallocatechin gallate) and GA as well as the interactions among them were the most probably ones to influence, or be influenced by the fungal communities during the fermentation process of Fu brick tea. This study revealed fungal succession, metabolite changes and their relationships, provided new insights into the mechanisms for manufacturing process of Fu brick tea.

Mushroom-Derived Indole Alkaloids

Mushrooms are known to produce over 140 natural products bearing an indole heterocycle. In this review, the isolation of these mushroom-derived indole alkaloids is discussed, along with their associated biological activities.

Polyphasic taxonomy of Aspergillus section Aspergillus (formerly Eurotium), and its occurrence in indoor environments and food

Aspergillus section Aspergillus (formerly the genus Eurotium) includes xerophilic species with uniseriate conidiophores, globose to subglobose vesicles, green conidia and yellow, thin walled eurotium-like ascomata with hyaline, lenticular ascospores. In the present study, a polyphasic approach using morphological characters, extrolites, physiological characters and phylogeny was applied to investigate the taxonomy of this section. Over 500 strains from various culture collections and new isolates obtained from indoor environments and a wide range of substrates all over the world were identified using calmodulin gene sequencing. Of these, 163 isolates were subjected to molecular phylogenetic analyses using sequences of ITS rDNA, partial β-tubulin (BenA), calmodulin (CaM) and RNA polymerase II second largest subunit (RPB2) genes. Colony characteristics were documented on eight cultivation media, growth parameters at three incubation temperatures were recorded and micromorphology was examined using light microscopy as well as scanning electron microscopy to illustrate and characterize each species. Many specific extrolites were extracted and identified from cultures, including echinulins, epiheveadrides, auroglaucins and anthraquinone bisanthrons, and to be consistent in strains of nearly all species. Other extrolites are species-specific, and thus valuable for identification. Several extrolites show antioxidant effects, which may be nutritionally beneficial in food and beverages. Important mycotoxins in the strict sense, such as sterigmatocystin, aflatoxins, ochratoxins, citrinin were not detected despite previous reports on their production in this section. Adopting a polyphasic approach, 31 species are recognized, including nine new species. ITS is highly conserved in this section and does not distinguish species. All species can be differentiated using CaM or RPB2 sequences. For BenA, Aspergillus brunneus and A. niveoglaucus share identical sequences. Ascospores and conidia morphology, growth rates at different temperatures are most useful characters for phenotypic species identification.

Mold allergy: is it real and what do we do about it?

INTRODUCTION

fungi produce substances that contain pathogen-associated molecular patterns (pamps) and damage-associated molecular patterns (damps) which bind to pattern recognition receptors, stimulating innate immune responses in humans. they also produce allergens that induce production of specific ige. Areas covered: In this review we cover both innate and adaptive immune responses to fungi. Some fungal products can activate both innate and adaptive responses and in doing so, cause an intense and complex health effects. Methods of testing for fungal allergy and evidence for clinical treatment including environmental control are also discussed. In addition, we describe controversial issues including the role of Stachybotrys and mycotoxins in adverse health effects. Expert commentary: Concerns about long-term exposure to fungi have led some patients, attorneys and fungus advocates to promote fears about a condition that has been termed toxic mold syndrome. This syndrome is associated with vague symptoms and is believed to be due to exposure to mycotoxins, though this connection has not been proven. Ultimately, more precise methods are needed to measure both fungal exposure and the resulting health effects. Once that such methods become available, much of the speculation will be replaced by knowledge.

Neoechinulin A induced memory improvements and antidepressant-like effects in mice

Neoechinulin A is an isoprenyl indole alkaloid that exhibits scavenging, neurotrophic factor-like, and anti-apoptotic activities. However, the effectiveness of neoechinulin A in animal models of disease has not yet been explored. In the present study, we investigated the effects of neoechinulin A on memory impairment in lipopolysaccharide (LPS)-treated mice and its antidepressant-like effects in mice. In the Y-maze test, the intracerebroventicular (i.c.v.) administration of LPS (10μg/mouse) significantly decreased spontaneous alternation behavior, which was prevented by the prior administration of neoechinulin A (300ng/mouse, i.c.v.). None of the treatments altered the locomotor activity of mice. Moreover, the administration of neoechinulin A decreased the immobility time in the forced-swim test or tail suspension test, which was prevented by the prior administration of WAY100635 (an antagonist of 5-HT1A receptors) and parachlorophenylalanine (an inhibitor of tryptophan hydroxylase). These results suggest that neoechinulin A improves memory functions in LPS-treated mice, and also exerts antidepressant-like effects through changes in the 5-HT system.

Molecular screening of xerophilic Aspergillus strains producing mycophenolic acid

Mycophenolic acid (MPA) is the fungal secondary metabolite displaying several biological properties. Up to now, screening of fungal strains producing MPA has mainly been the result of the search of this molecule in their culture medium by chemical methods. Here we developed a molecular approach by targeting the expression level of the MpaC gene encoding the polyketide synthase, one of the key enzymes involved in the MPA synthesis. Thirty xerophilic Aspergillus strains were identified using the RNA polymerase II subunit and the β-tubulin genes. Seven Aspergillus species were evidenced. The expression level of the MpaC gene was quantified and compared to the MPA production rate. Only Aspergillus pseudoglaucus and all the eight strains of this species produced MPA. While the MpaC gene was not expressed or weakly expressed in the MPA non-producing strains, all the A. pseudoglaucus strains presented a high level of expression of this gene. The highest expression level of the MpaC gene among the MPA non-producing strains was significantly lower than the lowest expression level of this gene in the MPA producing strains. To our knowledge, this is the first study that demonstrates the effectiveness of molecular approach for the screening of MPA-producing species.

Structural Diversity and Biological Activities of Indole Diketopiperazine Alkaloids from Fungi

Indole diketopiperazine alkaloids are secondary metabolites of microorganisms that are widely distributed in filamentous fungi, especially in the genera Aspergillus and Penicillium of the phylum Ascomycota or sac fungi. These alkaloids represent a group of natural products characterized by diversity in both chemical structures and biological activities. This review aims to summarize 166 indole diketopiperazine alkaloids from fungi published from 1944 to mid-2015. The emphasis is on diverse chemical structures within these alkaloids and their relevant biological activities. The aim is to assess which of these compounds merit further study for purposes of drug development.

Aspergillus is monophyletic: Evidence from multiple gene phylogenies and extrolites profiles

Aspergillus is one of the economically most important fungal genera. Recently, the ICN adopted the single name nomenclature which has forced mycologists to choose one name for fungi (e.g. Aspergillus, Fusarium, Penicillium, etc.). Previously two proposals for the single name nomenclature in Aspergillus were presented: one attributes the name "Aspergillus" to clades comprising seven different teleomorphic names, by supporting the monophyly of this genus; the other proposes that Aspergillus is a non-monophyletic genus, by preserving the Aspergillus name only to species belonging to subgenus Circumdati and maintaining the sexual names in the other clades. The aim of our study was to test the monophyly of Aspergilli by two independent phylogenetic analyses using a multilocus phylogenetic approach. One test was run on the publicly available coding regions of six genes (RPB1, RPB2, Tsr1, Cct8, BenA, CaM), using 96 species of Penicillium, Aspergillus and related taxa. Bayesian (MrBayes) and Ultrafast Maximum Likelihood (IQ-Tree) and Rapid Maximum Likelihood (RaxML) analyses gave the same conclusion highly supporting the monophyly of Aspergillus. The other analyses were also performed by using publicly available data of the coding sequences of nine loci (18S rRNA, 5,8S rRNA, 28S rRNA (D1-D2), RPB1, RPB2, CaM, BenA, Tsr1, Cct8) of 204 different species. Both Bayesian (MrBayes) and Maximum Likelihood (RAxML) trees obtained by this second round of independent analyses strongly supported the monophyly of the genus Aspergillus. The stability test also confirmed the robustness of the results obtained. In conclusion, statistical analyses have rejected the hypothesis that the Aspergilli are non-monophyletic, and provided robust arguments that the genus is monophyletic and clearly separated from the monophyletic genus Penicillium. There is no phylogenetic evidence to split Aspergillus into several genera and the name Aspergillus can be used for all the species belonging to Aspergillus i.e. the clade comprising the subgenera Aspergillus, Circumdati, Fumigati, Nidulantes, section Cremei and certain species which were formerly part of the genera Phialosimplex and Polypaecilum. Section Cremei and the clade containing Polypaecilum and Phialosimplex are proposed as new subgenera of Aspergillus. The phylogenetic analysis also clearly shows that Aspergillus clavatoflavus and A. zonatus do not belong to the genus Aspergillus. Aspergillus clavatoflavus is therefore transferred to a new genus Aspergillago as Aspergillago clavatoflavus and A. zonatus was transferred to Penicilliopsis as P. zonata. The subgenera of Aspergillus share similar extrolite profiles indicating that the genus is one large genus from a chemotaxonomical point of view. Morphological and ecophysiological characteristics of the species also strongly indicate that Aspergillus is a polythetic class in phenotypic characters.

Fungal secondary metabolite analysis applied to Cultural Heritage: the case of a contaminated library in Venice

The secondary metabolite production of several fungal strains of Aspergillus creber, Aspergillus jensenii, Aspergillus penicillioides, Aspergillus protuberus, Aspergillus vitricola, Cladosporium cladosporioides, Eurotium chevalieri, Eurotium halophilicum, Penicillium brevicompactum and Penicillium chrysogenum were characterised by liquid chromatography tamdem mass spectometry. All fungi were isolated from both air and book covers as well as from settled dust from a contaminated library in Venice (Italy). For A. creber and A. jensenii, we identified sterigmatocystin, methoxysterigmatocystin, versicolorin A and related precursors/side metabolites from the biosynthetic pathways. Deoxybrevianamid E, neoechinulin A, pseurotin A and D, and rugulusovin were principally detected from the strains of E. halophilicum, an emerging fungal species implicated in book contaminations in specific indoor niches. The analysis of settled dust showed a wide range of toxic or bioactive fungal metabolites. Forty-five different metabolites were identified in different concentrations; in particular, high amounts of asperglaucide, alamethicin, andrastin A, terrecyclic acid and neoechinulin A were detected. Also one bacterial metabolite, chloramphenicole was detected. This study increases the knowledge about metabolite production of several fungal species, as well as on the indoor presence of fungi that are not detected by aerobiological sampling. These results emphasise how routine dusting operations are necessary and essential in order to prevent further microbiological developments in library environments.

Production of New Cladosporin Analogues by Reconstitution of the Polyketide Synthases Responsible for the Biosynthesis of this Antimalarial Agent

The antimalarial agent cladosporin is a nanomolar inhibitor of the Plasmodium falciparum lysyl-tRNA synthetase, and exhibits activity against both blood- and liver-stage infection. Cladosporin can be isolated from the fungus Cladosporium cladosporioides, where it is biosynthesized by a highly reducing (HR) and a non-reducing (NR) iterative type I polyketide synthase (PKS) pair. Genome sequencing of the host organism and subsequent heterologous expression of these enzymes in Saccharomyces cerevisiae produced cladosporin, confirming the identity of the putative gene cluster. Incorporation of a pentaketide intermediate analogue indicated a 5+3 assembly by the HR PKS Cla2 and the NR PKS Cla3 during cladosporin biosynthesis. Advanced-intermediate analogues were synthesized and incorporated by Cla3 to furnish new cladosporin analogues. A putative lysyl-tRNA synthetase resistance gene was identified in the cladosporin gene cluster. Analysis of the active site emphasizes key structural features thought to be important in resistance to cladosporin.

Cytotoxic and genotoxic potencies of single and combined spore extracts of airborne OTA-producing and OTA-non-producing Aspergilli in Human lung A549 cells

Aspergillus sclerotiorum (AS) is a well-known producer of ochratoxin A (OTA) while Aspergillus pseudoglaucus (AP) produces a wide range of extrolites with poorly investigated toxicity. These species are frequently co-occur in grain mill aeromycota. The aim of this study was to determine OTA levels in spore extracts using HPLC and immunoaffinity columns, and to examine the cytotoxicity of pure OTA, OTA-positive (AS-OTA(+)) and OTA-negative (AS-OTA(-)) spore extracts, as well as of AP spore extract, on human lung adenocarcinoma cells A549, individually and in combination, using a colorimetric MTT test (540nm). To establish which type of cell death predominated after treatments, a quantitative fluorescent assay with ethidium bromide and acridine orange was used, and the level of primary DNA damage in A549 cells was evaluated using the alkaline comet assay. OTA was detected in spore extracts (0.3-28µg/mL) of 3/6 of the AS strains, while none of the tested AP strains were able to produce OTA. Taking into account the maximum detected concentration of OTA in the spores, the daily intake of OTA by inhalation was calculated to be 1ng/kg body weight (b.w.), which is below the tolerable daily intake for OTA (17ng/kg b.w.). Using the MTT test, the following IC50 values were obtained: single OTA (53μg/mL); AS-OTA(+) (mass concentration 934μg/mL corresponds to 10.5μg/mL of OTA in spore extract); and 2126μg/mL for AP. The highest applied concentration of AS-OTA(-) spore extract (4940μg/mL) decreased cell viability by 30% and IC50 for the extract could not be determined. Single OTA and AS-OTA(+) and combinations (AP+AS-OTA(+) and AP+AS-OTA(-)) in subtoxic concentrations provoked significant primary DNA damage, apoptosis, and to a lesser extent, necrosis in A549 cells. Mixture of AP+AS-OTA(+) and AP+AS-OTA(-) in subtoxic concentrations showed dominant additive interactions. Despite the low calculated daily intake of OTA by inhalation, our results suggest that chronic exposure to high levels of OTA-producing airborne fungi in combination with other more or less toxic moulds pose a significant threat to human health due to their possible additive and/or synergistic interactions.

Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs

Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds.

3-Nitroasterric Acid Derivatives from an Antarctic Sponge-Derived Pseudogymnoascus sp. Fungus

Four new nitroasterric acid derivatives, pseudogymnoascins A-C (1-3) and 3-nitroasterric acid (4), along with the two known compounds questin and pyriculamide, were obtained from the cultures of a Pseudogymnoascus sp. fungus isolated from an Antarctic marine sponge belonging to the genus Hymeniacidon. The structures of the new compounds were determined by extensive NMR and MS analyses. These compounds are the first nitro derivatives of the known fungal metabolite asterric acid. Several asterric acid derivatives isolated from other fungal strains have shown antibacterial and antifungal activities. However, the new compounds described in this work were inactive against a panel of bacteria and fungi (MIC > 64 μg/mL).

Taxonomy, chemodiversity, and chemoconsistency of Aspergillus, Penicillium, and Talaromyces species

Aspergillus, Penicillium, and Talaromyces are among the most chemically inventive of all fungi, producing a wide array of secondary metabolites (exometabolites). The three genera are holophyletic in a cladistic sense and polythetic classes in an anagenetic or functional sense, and contain 344, 354, and 88 species, respectively. New developments in classification, cladification, and nomenclature have meant that the species, series, and sections suggested are natural groups that share many extrolites, including exometabolites, exoproteins, exocarbohydrates, and exolipids in addition to morphological features. The number of exometabolites reported from these species is very large, and genome sequencing projects have shown that a large number of additional exometabolites may be expressed, given the right conditions (“cryptic” gene clusters for exometabolites). The exometabolites are biosynthesized via shikimic acid, tricarboxylic acid cycle members, nucleotides, carbohydrates or as polyketides, non-ribosomal peptides, terpenes, or mixtures of those. The gene clusters coding for these compounds contain genes for the biosynthetic building blocks, the linking of these building blocks, tailoring enzymes, resistance for own products, and exporters. Species within a series or section in Aspergillus, Penicillium, and Talaromyces have many exometabolites in common, seemingly acquired by cladogenesis, but some the gene clusters for autapomorphic exometabolites may have been acquired by horizontal gene transfer. Despite genome sequencing efforts, and the many breakthroughs these will give, it is obvious that epigenetic factors play a large role in evolution and function of chemodiversity, and better methods for characterizing the epigenome are needed. Most of the individual species of the three genera produce a consistent and characteristic profile of exometabolites, but growth medium variations, stimulation by exometabolites from other species, and variations in abiotic intrinsic and extrinsic environmental factors such as pH, temperature, redox potential, and water activity will add significantly to the number of biosynthetic families expressed in anyone species. An example of the shared exometabolites in a natural group such as Aspergillus section Circumdati series Circumdati is that most, but not all species produce penicillic acids, aspyrones, neoaspergillic acids, xanthomegnins, melleins, aspergamides, circumdatins, and ochratoxins, in different combinations.

Genome and physiology of the ascomycete filamentous fungus Xeromyces bisporus, the most xerophilic organism isolated to date

Xeromyces bisporus can grow on sugary substrates down to 0.61, an extremely low water activity. Its genome size is approximately 22 Mb. Gene clusters encoding for secondary metabolites were conspicuously absent; secondary metabolites were not detected experimentally. Thus, in its 'dry' but nutrient-rich environment, X. bisporus appears to have relinquished abilities for combative interactions. Elements to sense/signal osmotic stress, e.g. HogA pathway, were present in X. bisporus. However, transcriptomes at optimal (∼ 0.89) versus low aw (0.68) revealed differential expression of only a few stress-related genes; among these, certain (not all) steps for glycerol synthesis were upregulated. Xeromyces bisporus increased glycerol production during hypo- and hyper-osmotic stress, and much of its wet weight comprised water and rinsable solutes; leaked solutes may form a protective slime. Xeromyces bisporus and other food-borne moulds increased membrane fatty acid saturation as water activity decreased. Such modifications did not appear to be transcriptionally regulated in X. bisporus; however, genes modulating sterols, phospholipids and the cell wall were differentially expressed. Xeromyces bisporus was previously proposed to be a 'chaophile', preferring solutes that disorder biomolecular structures. Both X. bisporus and the closely related xerophile, Xerochrysium xerophilum, with low membrane unsaturation indices, could represent a phylogenetic cluster of 'chaophiles'.