Epigenetic modifier induced enhancement of fumiquinazoline C production in Aspergillus fumigatus (GA-L7): an endophytic fungus from Grewia asiatica L

A Close View of the Production of Bioactive Fungal Metabolites Mediated by Chromatin Modifiers

Secondary metabolites produced by fungi are well known for their biological properties, which play important roles in medicine. These metabolites aid in managing infections and treating chronic illnesses, thereby contributing substantially to human health improvement. Despite this extensive knowledge, the vast biodiversity and biosynthetic potential of fungi is still largely unexplored, highlighting the need for further research in natural products. In this review, several secondary metabolites of fungal origin are described, emphasizing novel structures and skeletons. The detection and characterization of these metabolites have been significantly facilitated by advancements in analytical systems, particularly modern hyphenated liquid chromatography/mass spectrometry. These improvements have primarily enhanced sensitivity, resolution, and analysis flow velocity. Since the in vitro production of novel metabolites is often lower than the re-isolation of known metabolites, understanding chromatin-based alterations in fungal gene expression can elucidate potential pathways for discovering new metabolites. Several protocols for inducing metabolite production from different strains are discussed, demonstrating the need for uniformity in experimental procedures to achieve consistent biosynthetic activation.

Endophytic fungi: A future prospect for breast cancer therapeutics and drug development

Globally, breast cancer is a primary contributor to cancer-related fatalities and illnesses among women. Consequently, there is a pressing need for safe and effective treatments for breast cancer. Bioactive compounds from endophytic fungi that live in symbiosis with medicinal plants have garnered significant interest in pharmaceutical research due to their extensive chemical composition and prospective medicinal attributes. This review underscores the potentiality of fungal endophytes as a promising resource for the development of innovative anticancer agents specifically tailored for breast cancer therapy. The diversity of endophytic fungi residing in medicinal plants, success stories of key endophytic bioactive metabolites tested against breast cancer and the current progress with regards to in vivo studies and clinical trials on endophytic fungal metabolites in breast cancer research forms the underlying theme of this article. A thorough compilation of putative anticancer compounds sourced from endophytic fungi that have demonstrated therapeutic potential against breast cancer, spanning the period from 1990 to 2022, has been presented. This review article also outlines the latest trends in endophyte-based drug discovery, including the use of artificial intelligence, machine learning, multi-omics approaches, and high-throughput strategies. The challenges and future prospects associated with fungal endophytes as substitutive sources for developing anticancer drugs targeting breast cancer are also being highlighted.

Epigenetic modifiers as inducer of bioactive secondary metabolites in fungi

Scientists are making efforts to search for new metabolites as they are essential lead molecules for the drug discovery, much required due to the evolution of multi drug resistance and new diseases. Moreover, higher production of known drugs is required because of the ever growing population. Microorganisms offer a vast collection of chemically distinct compounds that exhibit various biological functions. They play a crucial role in safeguarding crops, agriculture, and combating several infectious ailments and cancer. Research on fungi have grabbed a lot of attention after the discovery of penicillin, most of the compounds produced by fungi under normal cultivation conditions are discovered and now rarely new compounds are discovered. Treatment of fungi with the epigenetic modifiers has been becoming very popular since the last few years to boost the discovery of new molecules and enhance the production of already known molecules. Epigenetic literally means above genetics that actually does not alter the genome but alter its expression by altering the state of chromatin from heterochromatin to euchromatin. Chromatin in heterochromatin state usually doesn't express because it is closely packed by histones in this state. Epigenetic modifiers loosen the packing of chromatin by inhibiting DNA methylation and histone deacetylation and thus permit the expression of genes that usually remain dormant. This study delves into the possibility of utilizing epigenetic modifying agents to generate pharmacologically significant secondary metabolites from fungi.

Structural diversity of microbial secondary metabolites based on chemical epigenetic manipulation

Fungi are microorganisms with biosynthetic potential that are capable of producing a wide range of chemically diverse and biologically interesting small molecules. Chemical epigenetic manipulation has been increasingly explored as a simple and powerful tool to induce the production of additional microbial secondary metabolites in fungi. This review focuses on chemical epigenetic manipulation in fungi and summarizes 379 epigenetic manipulation products discovered from 2008 to 2022 to promote the discovery of their medicinal value.

Epigenetic manipulation for secondary metabolite activation in endophytic fungi: current progress and future directions

Fungal endophytes have emerged as a promising source of secondary metabolites with significant potential for various applications in the field of biomedicine. The biosynthetic gene clusters of endophytic fungi are responsible for encoding several enzymes and transcriptional factors that are involved in the biosynthesis of secondary metabolites. The investigation of fungal metabolic potential at genetic level faces certain challenges, including the synthesis of appropriate amounts of chemicals, and loss of the ability of fungal endophytes to produce secondary metabolites in an artificial culture medium. Therefore, there is a need to delve deeper into the field of fungal genomics and transcriptomics to explore the potential of fungal endophytes in generating secondary metabolites governed by biosynthetic gene clusters. The silent biosynthetic gene clusters can be activated by modulating the chromatin structure using chemical compounds. Epigenetic modification plays a significant role by inducing cryptic gene responsible for the production of secondary metabolites using DNA methyl transferase and histone deacetylase. CRISPR-Cas9-based genome editing emerges an effective tool to enhance the production of desired metabolites by modulating gene expression. This review primarily focuses on the significance of epigenetic elicitors and their capacity to boost the production of secondary metabolites from endophytes. This article holds the potential to rejuvenate the drug discovery pipeline by introducing new chemical compounds.

Bioactive compounds and biomedical applications of endophytic fungi: a recent review

Human life has been significantly impacted by the creation and spread of novel species of antibiotic-resistant bacteria and virus strains that are difficult to manage. Scientists and researchers have recently been motivated to seek out alternatives and other sources of safe and ecologically friendly active chemicals that have a powerful and effective effect against a wide variety of pathogenic bacteria as a result of all these hazards and problems. In this review, endophytic fungi and their bioactive compounds and biomedical applications were discussed. Endophytes, a new category of microbial source that can produce a variety of biological components, have major values for study and broad prospects for development. Recently, endophytic fungi have received much attention as a source for new bioactive compounds. In addition, the variety of natural active compounds generated by endophytes is due to the close biological relationship between endophytes and their host plants. The bioactive compounds separated from endophytes are usually classified as steroids, xanthones, terpenoids, isocoumarins, phenols, tetralones, benzopyranones and enniatines. Moreover, this review discusses enhancement methods of secondary metabolites production by fungal endophytes which include optimization methods, co-culture method, chemical epigenetic modification and molecular-based approaches. Furthermore, this review deals with different medical applications of bioactive compounds such as antimicrobial, antiviral, antioxidant and anticancer activities in the last 3 years.

Endophytic fungi mediates production of bioactive secondary metabolites via modulation of genes involved in key metabolic pathways and their contribution in different biotechnological sector

Endophytic fungi stimulate the production of an enormous number of bioactive metabolites in medicinal plants and affect the different steps of biosynthetic pathways of these secondary metabolites. Endophytic fungi possess a number of biosynthetic gene clusters that possess genes for various enzymes, transcription factors, etc., in their genome responsible for the production of secondary metabolites. Additionally, endophytic fungi also modulate the expression of various genes responsible for the synthesis of key enzymes involved in metabolic pathways of such as HMGR, DXR, etc. involved in the production of a large number of phenolic compounds as well as regulate the expression of genes involved in the production of alkaloids and terpenoids in different plants. This review aims to provide a comprehensive overview of gene expression related to endophytes and their impact on metabolic pathways. Additionally, this review will emphasize the studies done to isolate these secondary metabolites from endophytic fungi in large quantities and assess their bioactivity. Due to ease in synthesis of secondary metabolites and their huge application in the medical industry, these bioactive metabolites are now being extracted from strains of these endophytic fungi commercially. Apart from their application in the pharmaceutical industry, most of these metabolites extracted from endophytic fungi also possess plant growth-promoting ability, bioremediation potential, novel bio control agents, sources of anti-oxidants, etc. The review will comprehensively shed a light on the biotechnological application of these fungal metabolites at the industrial level.

Epigenetic Induction of Secondary Metabolites Production in Endophytic Fungi Penicillium chrysogenum and GC-MS Analysis of Crude Metabolites with Anti-HIV-1 Activity

The continuous burden of human immunodeficiency virus-1 in Sub-Saharan Africa, coupled with the inability of antiretroviral agents to eradicate HIV-1 from viral reservoirs, the potential risks of drug resistance development, and the development of adverse effects, emphasizes the need to develop a new class of HIV-1 inhibitors. Here, we cultivated four endophytic fungal isolates from a medicinal plant, Albizia adianthifolia with the addition of small epigenetic modifiers, sodium butyrate, and valproic acid, to induce the expression of biosynthetic gene clusters encoding active secondary metabolites with probable anti-HIV activities. We identified a non-toxic crude extract of the endophytic fungus Penicillium chrysogenum treated with sodium butyrate to possess significantly greater anti-HIV activity than the untreated extracts. Penicillium chrysogenum P03MB2 showed anti-HIV activity with an IC₅₀ of 0.6024 µg/mL compared to untreated fungal crude extract (IC₅₀ 5.053 µg/mL) when treated with sodium butyrate. The profile of secondary metabolite compounds from the bioactive, partially purified extracts were identified by gas chromatography-mass spectrometry (GC-MS), and more bioactive compounds were detected in treated P. chrysogenum P03MB2 fractions than in untreated fractions. Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro (13.64%), cyclotrisiloxane, hexamethyl (8.18%), cyclotetrasiloxane, octamethyl (7.23%), cyclopentasiloxane, decamethyl (6.36%), quinoline, 1,2-dihydro-2,24-trimethyl (5.45%), propanenitrile (4.55%), deca-6,9-diene (4.55%), dibutyl phthalate (4.55%), and silane[1,1-dimethyl-2-propenyl)oxy]dimethyl (2.73%) were the most abundant compounds. These results indicate that treatment of endophytic fungi with small epigenetic modifiers enhances the secretion of secondary metabolites with stronger anti-HIV-1 properties, acknowledging the feasibility of epigenetic modification as an innovative approach for the discovery of cryptic fungal metabolites which can be developed into therapeutic compounds.

Recent Advances in Search of Bioactive Secondary Metabolites from Fungi Triggered by Chemical Epigenetic Modifiers

Genomic analysis has demonstrated that many fungi possess essential gene clusters for the production of previously unobserved secondary metabolites; however, these genes are normally reduced or silenced under most conditions. These cryptic biosynthetic gene clusters have become treasures of new bioactive secondary metabolites. The induction of these biosynthetic gene clusters under stress or special conditions can improve the titers of known compounds or the production of novel compounds. Among the inducing strategies, chemical-epigenetic regulation is considered a powerful approach, and it uses small-molecule epigenetic modifiers, which mainly act as the inhibitors of DNA methyltransferase, histone deacetylase, and histone acetyltransferase, to promote changes in the structure of DNA, histones, and proteasomes and to further activate cryptic biosynthetic gene clusters for the production of a wide variety of bioactive secondary metabolites. These epigenetic modifiers mainly include 5-azacytidine, suberoylanilide hydroxamic acid, suberoyl bishydroxamic acid, sodium butyrate, and nicotinamide. This review gives an overview on the method of chemical epigenetic modifiers to trigger silent or low-expressed biosynthetic pathways to yield bioactive natural products through external cues of fungi, mainly based on the research progress in the period from 2007 to 2022. The production of about 540 fungal secondary metabolites was found to be induced or enhanced by chemical epigenetic modifiers. Some of them exhibited significant biological activities such as cytotoxic, antimicrobial, anti-inflammatory, and antioxidant activity.

Enhancing the Discovery of Bioactive Secondary Metabolites From Fungal Endophytes Using Chemical Elicitation and Variation of Fermentation Media

Endophytic microorganisms are an important source of bioactive secondary metabolites. In this study, fungal endophytes obtained from A*STAR’s Natural Product Library (NPL) and previously isolated from different habitats of Singapore were investigated for their diversity, antimicrobial, and cytotoxic activities. A total of 222 fungal strains were identified on the basis of sequence analysis of ITS region of the rDNA gene. The identified fungal strains belong to 59 genera distributed in 20 orders. Majority of the identified strains (99%; 219 strains) belong to the phylum Ascomycota, while two strains belonged to the phylum Basidiomycota, and only one strain was from Mucoromycota phylum. The most dominant genus was Colletotrichum accounting for 27% of all the identified strains. Chemical elicitation using 5-azacytidine and suberoylanilide hydroxamic acid (SAHA) and variation of fermentation media resulted in the discovery of more bioactive strains. Bioassay-guided isolation and structure elucidation of active constituents from three prioritized fungal strains: Lophiotrema sp. F6932, Muyocopron laterale F5912, and Colletotrichum tropicicola F10154, led to the isolation of a known compound; palmarumycin C₈ and five novel compounds; palmarumycin CP₃₀, muyocopronol A-C and tropicicolide. Tropicicolide displayed the strongest antifungal activity against Aspergillus fumigatus with an IC₅₀ value of 1.8 μg/ml but with a weaker activity against the Candida albicans presenting an IC₅₀ of 7.1 μg/ml. Palmarumycin C₈ revealed the best antiproliferative activity with IC₅₀ values of 1.1 and 2.1 μg/ml against MIA PaCa-2 and PANC-1 cells, respectively.

Secondary metabolites produced by Macrophomina phaseolina, a fungal root endophyte of Brugmansia aurea, using classical and epigenetic manipulation approach

Endophytic fungi are rich sources of structurally complex chemical scaffolds with interesting biological activities. However, their metabolome is still unknown, making them appealing for novel compound discovery. To maximize the number of secondary metabolites produced from a single microbial source, we used the "OSMAC (one strain-many compounds) approach." In potato dextrose medium, M. phaseolina produced phomeolic acid (1), ergosterol peroxide (2), and a volatile compound 1,4-benzene-diol. Incorporating an epigenetic modifier, sodium valproate, affected the metabolite profile of the fungus. It produced 3-acetyl-3-methyl dihydro-furan-2(3H)-one (3) and methyl-2-(methyl-thio)-butyrate (4), plus volatile chemicals: butylated hydroxy toluene (BHT), di-methyl-formamide, 3-amino-1-propanol, and 1,4-benzenediol, 2-amino-1-(O-methoxyphenyl) propane. The structure of compounds 1-4 was established with the help of spectroscopic data. This study revealed first-time compounds 1-4 in the fungus M. phaseolina using a classical and epigenetic manipulation approach.

Study on Secondary Metabolites of Endophytic Fungus, Aspergillus fumigatus, from Crocus sativus L. Guided byUHPLC-HRMS/MS-Based Molecular Network

As a traditional Chinese medicine, Crocus sativus Linn has been used for a long time in China. However, the studies on secondary metabolites of its endophytic fungi were not fully sufficient. Thus, the endophytic fungus, Aspergillus fumigatus, collected from the lateral buds of C. sativus, was here investigated. An approach combining UHPLC-HRMS/MS (ultra-high performance liquid chromatography-high resolution mass spectrometry) with molecular network was carried out to construct a molecular network of crude EtOAc extract (CEE) of A. fumigatus, in which 32 chemical compounds were annotated. On the basis of analysis results, a total of 15 known natural compounds were isolated from CEE. Among them, compounds 11 and 12 were isolated for the first time from the genus Aspergillus. Moreover, CEE and compound 7 exhibited moderate inhibitory activity against Erwinia sp. with a MIC value of 100 μg/mL. This study provided a more convenient and rapid approach to investigating the crude extract with complex components of A. fumigatus, which is of great benefit to the further study and utilization of secondary metabolites of the genus Aspergillus.

Fungal Endophytes: an Accessible Source of Bioactive Compounds with Potential Anticancer Activity

Endophytes either be bacteria, fungi, or actinomycetes colonize inside the tissue of host plants without showing any immediate negative effects on them. Among numerous natural alternative sources, fungal endophytes produce a wide range of structurally diverse bioactive metabolites including anticancer compounds. Considering the production of bioactive compounds in low quantity, genetic and physicochemical modification of the fungal endophytes is performed for the enhanced production of bioactive compounds. Presently, for the treatment of cancer, chemotherapy is majorly used, but the side effects of chemotherapy are of prime concern in clinical practices. Also, the drug-resistant properties of carcinoma cells, lack of cancer cells-specific medicine, and the side effects of drugs are the biggest obstacles in cancer treatment. The interminable requirement of potential drugs has encouraged researchers to seek alternatives to find novel bioactive compounds, and fungal endophytes seem to be a probable target for the discovery of anticancer drugs. The present review focuses a comprehensive literature on the major fungal endophyte-derived bioactive compounds which are presently been used for the management of cancer, biotic factors influencing the production of bioactive compounds and about the challenges in the field of fungal endophyte research.

Enhancement of cordycepin production from Cordyceps militaris culture by epigenetic modification

Cordycepin (3'-deoxyadenosine) is a nucleoside analogue and biosynthesised by Cordyceps militaris, an entomopathogenic fungus. In this study, an epigenetic modifier was applied to static liquid cultures to enhance cordycepin production. C. militaris was cultured in a static liquid culture, and valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, was supplemented in order to modifying the epigenetic status. Gene regulatory network was explored to understand the molecular mechanisms underlying cordycepin production. 50 micromolar of VPA enhanced cordycepin production by 41.187% via the upregulation of 5'-nucleotidase, adenylate kinase, phosphorybosyltransferase, Cns1, Cns2, Cnsa3, and Cns4 of C. militaris for at least 2 days after VPA treatment. The maximum production of cordycepin was 2,835.32 ± 34.35 mg/L in 400 mL-working volume. A scaled-up culture was established with a working volume of 10 L, which led to the slight decrease of cordycepin production. This might due to multifactorial effects, for instance limited aeration and an uneven dispersion of nutrients in the culture system. This scaled-up culture was still needed further optimization. The modification of epigenetic status by VPA significantly enhanced cordycepin production by altering key gene regulatory network of C. militaris. The strategy established in this study might be applicable to other microorganism culture in order to improving the production of bioactive compounds. This work aimed to enhance the production of cordycepin by modifying the epigenetic status of C. militaris, in which subsequently altered gene regulatory network of cordycepin biosynthesis pathway. The weekly supplementation of valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, significantly improve cordycepin production over 40%, compared to the untreated control, and the gene regulatory network of C. militaris was also adapted.

Epigenetic Activation of Silent Biosynthetic Gene Clusters in Endophytic Fungi Using Small Molecular Modifiers

The discovery of silent biosynthetic gene clusters (BGCs) in fungi provides unlimited prospects to harness the secondary metabolites encoded by gene clusters for various applications, including pharmaceuticals. Amplifying these prospects is the new interest in exploring fungi living in the extremes, such as those associated with plants (fungal endophytes). Fungal species in endosymbiosis relationship with plants are recognized as the future factories of clinically relevant agents since discovering that they can produce similar metabolites as their plant host. The endophytes produce these compounds in natural environments as a defense mechanism against pathogens that infect the plant host or as a strategy for mitigating competitors. The signaling cascades leading to the expression of silent biosynthetic gene clusters in the natural environment remain unknown. Lack of knowledge on regulatory circuits of biosynthetic gene clusters limits the ability to exploit them in the laboratory. They are often silent and require tailor-designed strategies for activation. Epigenetic modification using small molecular compounds that alter the chromatin network, leading to the changes in secondary metabolites profile, has achieved considerable success. This review aims to comprehensively analyze the secondary metabolite profiles expressed after treatment with various epigenetic modifiers. We first describe the regulatory circuits governing the expression of secondary metabolites in fungi. Following this, we provide a detailed review of the small molecular modifiers, their mechanism(s) of action, and the diverse chemistries resulting from epigenetic modification. We further show that genetic deletion or epigenetic inhibition of histone deacetylases does not always lead to the overexpression or induction of silent secondary metabolites. Instead, the response is more complex and often leads to differential expression of secondary metabolites. Finally, we propose using this strategy as an initial screening tool to dereplicate promising fungal species.

Comprehensive Guide to Extracting and Expressing Fungal Secondary Metabolites with Aspergillus fumigatus as a Case Study

Fungal secondary metabolites (SMs) have captured the interest of natural products researchers in academia and industry for decades. In recent years, the high rediscovery rate of previously characterized metabolites is making it increasingly difficult to uncover novel compounds. Additionally, the vast majority of fungal SMs reside in genetically intractable fungi or are silent under normal laboratory conditions in genetically tractable fungi. The fungal natural products community has broadly overcome these barriers by altering the physical growth conditions of the fungus and heterologous/homologous expression of biosynthetic gene cluster regulators or proteins. The protocols described here summarize vital methodologies needed when researching SM production in fungi. We also summarize the growth conditions, genetic backgrounds, and extraction protocols for every published SM in Aspergillus fumigatus, enabling readers to easily replicate the production of previously characterized SMs. Readers will also be equipped with the tools for developing their own strategy for expressing and extracting SMs from their given fungus or a suitable heterologous model system. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Making glycerol stocks from spore suspensions Alternate Protocol 1: Creating glycerol stocks from non-sporulating filamentous fungi Basic Protocol 2: Activating spore-suspension glycerol stocks Basic Protocol 3: Extracting secondary metabolites from Aspergillus spp grown on solid medium Alternate Protocol 2: Extracting secondary metabolites from Aspergillus spp using ethyl acetate Alternate Protocol 3: High-volume metabolite extraction using ethyl acetate Alternate Protocol 4: Extracting secondary metabolites from Aspergillus spp in liquid medium Support Protocol: Creating an overlay culture Basic Protocol 4: Extracting DNA from filamentous fungi Basic Protocol 5: Creating a DNA construct with double-joint PCR Alternate Protocol 5: Creating a DNA construct with yeast recombineering Basic Protocol 6: Transformation of Aspergillus spp Basic Protocol 7: Co-culturing fungi and bacteria for extraction of secondary metabolites.

Chemical epigenetic modifiers enhance the production of immunosuppressants from the endophytic fungus Aspergillus fumigatus isolated from Cynodon dactylon

Chemical epigenetic modifiers applied on a plant endophytic fungus Aspergillus fumigatus isolated from a healthy stem of terrestrial plant Cynodon dactylon, significantly changed of metabolic profile and resulted in the isolation of nineteen compounds, including ten alkaloids (1-10), six polyketides (11-16), and three benzene derivatives (17-19). This is the first report of 14, 18 and 19 being isolated from this fungal species. And compound 14 was known as a synthetic product and isolated as a natural product for the first time. HPLC profiles of the control and treated samples indicated that compounds 11, 16, 18 are belonged to the newly induced secondary metabolites. Their structures were elucidated on the basis of extensive NMR spectroscopic and mass spectrometric analyses. The immunosuppressive and cytotoxic activities of all isolated compounds were evaluated.

Plant associated fungal endophytes as a source of natural bioactive compounds

Endophytes are a potent source of bioactive compounds that mimic plant-based metabolites. The relationship of host plant and endophyte is significantly associated with alteration in fungal colonisation and the extraction of endophyte-derived bioactive compounds. Screening of fungal endophytes and their relationship with host plants is essential for the isolation of bioactive compounds. Numerous bioactive compounds with antioxidant, antimicrobial, anticancer, and immunomodulatory properties are known to be derived from fungal endophytes. Bioinformatics tools along with the latest techniques such as metabolomics, next-generation sequencing, and metagenomics multilocus sequence typing can potentially fill the gaps in fungal endophyte research. The current review article focuses on bioactive compounds derived from plant-associated fungal endophytes and their pharmacological importance. We conclude with the challenges and opportunities in the research area of fungal endophytes.

Fungal Endophytes: A Promising Frontier for Discovery of Novel Bioactive Compounds

For years, fungi have served as repositories of bioactive secondary metabolites that form the backbone of many existing drugs. With the global rise in infections associated with antimicrobial resistance, in addition to the growing burden of non-communicable disease, such as cancer, diabetes and cardiovascular ailments, the demand for new drugs that can provide an improved therapeutic outcome has become the utmost priority. The exploration of microbes from understudied and specialized niches is one of the promising ways of discovering promising lead molecules for drug discovery. In recent years, a special class of plant-associated fungi, namely, fungal endophytes, have emerged as an important source of bioactive compounds with unique chemistry and interesting biological activities. The present review focuses on endophytic fungi and their classification, rationale for selection and prioritization of host plants for fungal isolation and examples of strategies that have been adopted to induce the activation of cryptic biosynthetic gene clusters to enhance the biosynthetic potential of fungal endophytes.

Metabolomic Analysis of The Chemical Diversity of South Africa Leaf Litter Fungal Species Using an Epigenetic Culture-Based Approach

Microbial natural products are an invaluable resource for the biotechnological industry. Genome mining studies have highlighted the huge biosynthetic potential of fungi, which is underexploited by standard fermentation conditions. Epigenetic effectors and/or cultivation-based approaches have successfully been applied to activate cryptic biosynthetic pathways in order to produce the chemical diversity suggested in available fungal genomes. The addition of Suberoylanilide Hydroxamic Acid to fermentation processes was evaluated to assess its effect on the metabolomic diversity of a taxonomically diverse fungal population. Here, metabolomic methodologies were implemented to identify changes in secondary metabolite profiles to determine the best fermentation conditions. The results confirmed previously described effects of the epigenetic modifier on the metabolism of a population of 232 wide diverse South Africa fungal strains cultured in different fermentation media where the induction of differential metabolites was observed. Furthermore, one solid-state fermentation (BRFT medium), two classic successful liquid fermentation media (LSFM and YES) and two new liquid media formulations (MCKX and SMK-II) were compared to identify the most productive conditions for the different populations of taxonomic subgroups.

Epigenetic Modifiers Affect the Bioactive Compounds Secreted by an Endophyte of the Tropical Plant Piper longum

Seven endophytic fungi were isolated from the tropical medicinal plant Piper longum L. After preliminary screening, Phomopsis heveicola was selected for the epigenetic activation treatments. The antibacterial, antifungal, and antioxidant potentials of crude extracts obtained from the treatments (with and without epigenetic modifiers) were analyzed in vitro. The extracts inhibited growth of the human pathogens Pseudomonas aeruginosa, Shigella sonnei, Streptococcus pyogenes, and Salmonella typhi, as well as the phytopathogens Puccinia recondita, Rhizoctonia solani, Phytophthora infestans, and Botrytis cinerea. Furthermore, DPPH-scavenging activity was higher in valproic acid treated extracts. Volatile chemicals with known biological activities (measured with GC-MS/MS), were released in the valproic acid treatment. The antimicrobial potentials of the extracts were confirmed using MRM/MS analysis. The experiments revealed a new promising endophytic fungus, P. heveicola, to be utilized in biological plant protection and in biomedical applications.

Isolation and Characterization of Serratiopeptidase Producing Bacteria from Mulberry Phyllosphere

Serratiopeptidase (EC 3.4.24.40), a proteolytic enzyme, is one of the most promising enzymes being used in biopharmaceutical industry. Mulberry phyllosphere, being an unexplored niche for exploration of protease production, was chosen for the present study. Protease producing bacteria were isolated from the tissues of mulberry plant as well as its rhizospheric soil. Two protease producing bacteria belonging to Serratia genus were found to be potential serratiopeptidase producers. Among them, the endophyte, i.e., Serratia marcescens MES-4 presented 95 Units/mL activity, while the soil isolate i.e., Serratia marcescens MRS-11 presented 156 Units/mL activity.

An anticonvulsive drug, valproic acid (valproate), has effects on the biosynthesis of fatty acids and polyketides in microorganisms

Valproic acid or valproate (VPA) is an anticonvulsive drug used for treatments of epilepsy, bipolar disorder, and migraine headaches. VPA is also an epigenetic modulator, inhibiting histone deacetylase, and it has been subjected to clinical study for cancer treatment. During the investigation of VPA on a metabolite profile in a fungus, we found that VPA has significant effects on the production of some fatty acids. Further exploration of VPA on fatty acid profiles of microorganisms, fungi, yeast, and bacteria, as well as representative gut microbiome, revealed that VPA could enhance or reduce the production of some fatty acids. VPA was found to induce the production of trans-9-elaidic acid, a fatty acid that was previously reported to have cellular effects in human macrophages. VPA could also inhibit the production of some polyketides produced by a model fungus. The present work suggests that the induction or inhibition of fatty acid biosynthesis by VPA (100 µM) in gut microbiome could give effects to patients treated with VPA because high doses of VPA oral administration (up to 600 mg to 900 mg) are used by patients; the concentration of VPA in the human gut may reach a concentration of 100 µM, which may give effects to gut microorganisms.

How Histone Deacetylase Inhibitors Alter the Secondary Metabolites of Botryosphaeria mamane, an Endophytic Fungus Isolated from Bixa orellana

Fungi are talented organisms able to produce several natural products with a wide range of structural and pharmacological activities. The conventional fungal cultivation used in laboratories is too poor to mimic the natural habitats of fungi, and this can partially explain why most of the genes responsible for the production of metabolites are transcriptionally silenced. The use of Histone Deacetylase inhibitors (HDACis) to perturb fungal secondary biosynthetic machinery has proven to be an effective approach for discovering new fungal natural products. The present study relates the effects of suberoylanilide hydroxamic acid (SAHA) and sodium valproate (VS) on the metabolome of Botryosphaeria mamane, an endophytic fungus isolated from Bixa orellana L. UHPLC/HR-MS analysis, integrated with four metabolomics tools: MS-DIAL, MS-FINDER, MetaboAnalyst and GNPS molecular networking, was established. This study highlighted that SAHA and VS changed metabolites in B. mamane, causing upregulation and downregulation of metabolites production. In addition, twelve compounds were detected in the extracts as metabolites structurally correlated to SAHA, indicating its important reactivity in the medium or its metabolism by the fungus. An addition of SAHA induced the production of eight metabolites while VS induced only two metabolites undetected in the control strain. This result illustrates the importance of adding HDACis to a fungal culture in order to induce metabolite production.

Novel Polyketides Produced by the Endophytic Fungus Aspergillus Fumigatus from Cordyceps Sinensis

Five new polyketides, including two pairs of enantiomers and a racemate, were isolated from the fermentation broth of Aspergillus fumigatus, an endophytic fungus isolated from Cordyceps sinensis. Their structures were identified using one-dimensional (1D) and two-dimensional (2D) NMR experiments, and the absolute configurations of the enantiomers were confirmed using electronic circular dichroism (ECD) calculations. Compounds 1a and 2a exhibited inhibitory activity against the MV4-11 cell line in vitro, with IC₅₀ values of 23.95 µM and 32.70 µM, respectively.

Endophytic Fungi: A Source of Potential Antifungal Compounds

The emerging and reemerging forms of fungal infections encountered in the course of allogeneic bone marrow transplantations, cancer therapy, and organ transplants have necessitated the discovery of antifungal compounds with enhanced efficacy and better compatibility. A very limited number of antifungal compounds are in practice against the various forms of topical and systemic fungal infections. The trends of new antifungals being introduced into the market have remained insignificant while resistance towards the introduced drug has apparently increased, specifically in patients undergoing long-term treatment. Considering the immense potential of natural microbial products for the isolation and screening of novel antibiotics for different pharmaceutical applications as an alternative source has remained largely unexplored. Endophytes are one such microbial community that resides inside all plants without showing any symptoms with the promise of producing diverse bioactive molecules and novel metabolites which have application in medicine, agriculture, and industrial set ups. This review substantially covers the antifungal compounds, including volatile organic compounds, isolated from fungal endophytes of medicinal plants during 2013⁻2018. Some of the methods for the activation of silent biosynthetic genes are also covered. As such, the compounds described here possess diverse configurations which can be a step towards the development of new antifungal agents directly or precursor molecules after the required modification.