Discovery of Two New Sorbicillinoids by Overexpression of the Global Regulator LaeA in a Marine-Derived Fungus Penicillium dipodomyis YJ-11

Cryptic piperazine derivatives activated by knocking out the global regulator LaeA in Aspergillus flavipes

Genome sequencing on an intertidal zone-derived Aspergillus flavipes strain revealed its great potential to produce secondary metabolites. To activate the cryptic compounds of A. flavipes, the global regulator flLaeA was knocked out, leading to substantial up-regulation of the expression of two NRPS-like biosynthetic gene clusters in the ΔflLaeA mutant. With a scaled-up fermentation of the ΔflLaeA strain, five compounds, including two previously undescribed piperazine derivatives flavipamides A and B (1 and 2), along with three known compounds (3-5), were obtained by LC-MS guided isolation. The new compounds were elucidated by spectroscopic analysis and electronic circular dichroism (ECD) calculations, and the biosynthetic pathway was proposed on the bias of bioinformatic analysis and 13C isotope labeling evidence. This is the first report to access cryptic fungi secondary metabolites by inactivating global regulator LaeA and may provide a new approach to discovering new secondary metabolites by such genetic manipulation.

Discovery of New Antimicrobial Metabolites in the Coculture of Medicinal Mushrooms

Bioactivity screening revealed that the antifungal activities of EtOAc extracts from coculture broths of Trametes versicolor SY630 with either Vanderbylia robiniophila SY341 or Ganoderma gibbosum SY1001 were significantly improved compared to that of monocultures. Activity-guided isolation led to the discovery of five aromatic compounds (1-5) from the coculture broth of T. versicolor SY630 and V. robiniophila SY341 and two sphingolipids (6 and 7) from the coculture broth of T. versicolor SY630 and G. gibbosum SY1001. Tramevandins A-C (1-3) and 17-ene-1-deoxyPS (6) are new compounds, while 1-deoxyPS (7) is a new natural product. Notably, compound 2 represents a novel scaffold, wherein the highly modified p-terphenyl bears a benzyl substituent. The absolute configurations of those new compounds were elucidated by X-ray diffraction, ECD calculations, and analysis of physicochemical constants. Compounds 1, 2, and 5-7 exhibited different degrees of antimicrobial activity, and the antifungal activities of compounds 6 and 7 against Candida albicans and Cryptococcus neoformans are comparable to those of fluconazole, nystatin, and sphingosine, respectively. Transcriptome analysis, propidium iodide staining, ergosterol quantification, and feeding assays showed that the isolated sphingolipids can extensively downregulate the late biosynthetic pathway of ergosterol in C. albicans, representing a promising mechanism to combat antibiotic-resistant fungi.

PrlaeA Affects the Production of Roquefortine C, Mycophenolic Acid, and Andrastin A in Penicillium roqueforti, but It Has Little Impact on Asexual Development

The regulation of fungal specialized metabolism is a complex process involving various regulators. Among these regulators, LaeA, a methyltransferase protein originally discovered in Aspergillus spp., plays a crucial role. Although the role of LaeA in specialized metabolism has been studied in different fungi, its function in Penicillium roqueforti remains unknown. In this study, we employed CRISPR-Cas9 technology to disrupt the laeA gene in P. roqueforti (PrlaeA) aiming to investigate its impact on the production of the specialized metabolites roquefortine C, mycophenolic acid, and andrastin A, as well as on asexual development, because they are processes that occur in the same temporal stages within the physiology of the fungus. Our results demonstrate a substantial reduction in the production of the three metabolites upon disruption of PrlaeA, suggesting a positive regulatory role of LaeA in their biosynthesis. These findings were further supported by qRT-PCR analysis, which revealed significant downregulation in the expression of genes associated with the biosynthetic gene clusters (BGCs) responsible for producing roquefortine C, mycophenolic acid, and andrastin A in the ΔPrlaeA strains compared with the wild-type P. roqueforti. Regarding asexual development, the disruption of PrlaeA led to a slight decrease in colony growth rate, while conidiation and conidial germination remained unaffected. Taken together, our results suggest that LaeA positively regulates the expression of the analyzed BGCs and the production of their corresponding metabolites in P. roqueforti, but it has little impact on asexual development.

Activation of a Silent Polyketide Synthase SlPKS4 Encoding the C7-Methylated Isocoumarin in a Marine-Derived Fungus Simplicillium lamellicola HDN13-430

Coumarins, isocoumarins and their derivatives are polyketides abundant in fungal metabolites. Although they were first discovered over 50 years ago, the biosynthetic process is still not entirely understood. Herein, we report the activation of a silent nonreducing polyketide synthase that encodes a C7-methylated isocoumarin, similanpyrone B (1), in a marine-derived fungus Simplicillium lamellicola HDN13-430 by heterologous expression. Feeding studies revealed the host enzymes can change 1 into its hydroxylated derivatives pestapyrone A (2). Compounds 1 and 2 showed moderate radical scavenging activities with ED50 values of 67.4 µM and 104.2 µM. Our discovery fills the gap in the enzymatic elucidation of naturally occurring C7-methylated isocoumarin derivatives.

AfLaeA, a Global Regulator of Mycelial Growth, Chlamydospore Production, Pathogenicity, Secondary Metabolism, and Energy Metabolism in the Nematode-Trapping Fungus Arthrobotrys flagrans

Arthrobotrys flagrans (Duddingtonia flagrans) is a typical nematode-trapping fungus which has been used for nematode biocontrol. The global regulator LaeA is widely distributed in filamentous fungi and plays a crucial role in secondary metabolism and development in addition to pathogenicity in fungal pathogens. In this study, the chromosome-level genome of A. flagrans CBS 565.50 was sequenced and homologous sequences of LaeA were identified in A. flagrans. A. flagrans LaeA (AfLaeA) knockout resulted in slower hyphal growth and a smoother hyphal surface. Importantly, deletion of AfLaeA resulted in the absence of chlamydospores and attenuated glycogen and lipid accumulation in hyphae. Similarly, disruption of the AfLaeA gene led to fewer traps and electron-dense bodies, lower protease activity, and a delay in capturing nematodes. The AfLaeA gene had a large effect on the secondary metabolism of A. flagrans, and both the deletion and overexpression of AfLaeA could yield new compounds, whereas some compounds were lost due to the absence of the AfLaeA. Protein-protein interactions between AfLaeA and another eight proteins were detected. Furthermore, transcriptome data analysis showed that 17.77% and 35.51% of the genes were influenced by the AfLaeA gene on days 3 and 7, respectively. AfLaeA gene deletion resulted in the higher expression level of the artA gene cluster, and multiple differentially expressed genes involved in glycogen and lipid synthesis and metabolism showed opposite expression patterns in wild-type and ΔAfLaeA strains. In summary, our results provide novel insights into the functions of AfLaeA in mycelial growth, chlamydospore production, pathogenicity, secondary metabolism, and energy metabolism in A. flagrans. IMPORTANCE The regulation of biological functions, such as the secondary metabolism, development, and pathogenicity of LaeA, has been reported in multiple fungi. But to date, no study on LaeA in nematode-trapping fungi has been reported. Moreover, it has not been investigated whether or not LaeA is involved in energy metabolism and chlamydospore formation has not been investigated. Especially in the formation mechanism of chlamydospores, several transcription factors and signaling pathways are involved in the production of chlamydospores, but the mechanism of chlamydospore formation from an epigenetic perspective has not been revealed. Concurrently, an understanding of protein-protein interactions will provide a broader perspective on the regulatory mechanism of AfLaeA in A. flagrans. This finding is critical for understanding the regulatory role of AfLaeA in the biocontrol fungus A. flagrans and establishes a foundation for developing high-efficiency nematode biocontrol agents.

New Sorbicillinoids from the Mangrove Endophytic Fungus Trichoderma reesei SCNU-F0042

Three new dimeric sorbicillinoids (1-3) and one new 3,4,6-trisubstituted α-pyrone (5), along with seven analogues (4 and 6-11), were isolated from the mangrove endophytic fungus Trichoderma reesei SCNU-F0042 under the guidance of molecular networking approach. Their chemical structures were established by 1D and 2D NMR HR-ESI-MS and ECD analysis. In a bioassay, compound 2 exhibited moderate SARS-CoV-2 inhibitory activity with an EC50 value of 29.0 μM.

Discovery of Novel Terpenoids from the Basidiomycete Pleurotus ostreatus through Genome Mining and Coculture Optimization

In our previous work, postredienes A-C, three unusual linear sesterterpenes with high antifungal activities, were isolated from Pleurotus ostreatus SY10 when cocultured with Trametes robiniophila SY636. However, their titers were low, and exploration of newly biosynthesized trace analogues is required. Herein, genome mining analysis predicted that 17 gene clusters are involved in terpenoid biosynthesis in P. ostreatus. Thus, coculture conditions for strains SY10 and SY636 were optimized using a single-factor test and Box-Behnken design. As a result, the titers of postredienes A-C were increased by over 2.5-fold, reaching 1.28 to 8.40 mg/L. Moreover, five new terpenoids, named postredienes D-H (1-5), were successfully isolated. Compound 1 exhibited activities against the human pathogenic fungi Candida albicans and Cryptococcus neoformans comparable to those of amphotericin B. Compound 2 represents a novel sesterterpene with a five-membered ring at C-7. The absolute configurations of 1-5 were elucidated by making the methoxyphenylacetic acid esters and acetonide derivatives, combined with ECD and NMR calculation. Two potential gene clusters and relevant biosynthetic pathways for 1-5 were subsequently proposed based on real-time reverse transcription-quantitative PCR (RT-qPCR) analysis. The current study provides new insights into the research of terpenoid biosynthesis genes in P. ostreatus and other basidiomycetes.

Effects of Carbon, Nitrogen, Ambient pH and Light on Mycelial Growth, Sporulation, Sorbicillinoid Biosynthesis and Related Gene Expression in Ustilaginoidea virens

Sorbicillinoids are a class of hexaketide metabolites produced by Ustilaginoidea virens (teleomorph: Villosiclava virens), an important fungal pathogen that causes a devastating rice disease. In this study, we investigated the effects of environmental factors, including carbon and nitrogen sources, ambient pH and light exposure, on mycelial growth, sporulation, as well as the accumulation of sorbicillinoids, and the expression of related genes involved in sorbicillinoid biosynthesis. It was found that the environmental factors had great influences on mycelial growth and sporulation of U. virens. Fructose and glucose, complex nitrogen sources, acidic conditions and light exposure were favorable for sorbicillinoid production. The relative transcript levels of sorbicillinoid biosynthesis genes were up-regulated when U. virens was separately treated with those environmental factors that favored sorbicillinoid production, indicating that sorbicillinoid biosynthesis was mainly regulated at the transcriptional level by different environmental factors. Two pathway-specific transcription factor genes, UvSorR1 and UvSorR2, were found to participate in the regulation of sorbicillinoid biosynthesis. These results will provide useful information to better understand the regulation mechanisms of sorbicillinoid biosynthesis, and be conducive to develop effective means for controlling sorbicillinoid production in U. virens.

Bioactive sorbicillinoids from a rhizospheric soil-derived Paecilomyces sp. KMU21009

A new hybrid sorbicillinoid named paeciureallin (1) and a new monomeric sorbicillinoid named paecillyketide (2), along with six known analogues (3-8), were isolated from the rhizospheric soil-derived fungus Paecilomyces sp. KMU21009 associated with Delphinium yunnanense. Their structures were elucidated by extensive spectroscopic analysis and comparison with literature values. Paeciureallin (1) is the first example of hybrid sorbicillinoids possessing a rare sorbicillinoid urea unit and containing a β-D-ribofuranose functionality. In pharmacological studies, compounds 1 and 2 were evaluated for in vitro anti-inflammatory and cytotoxic activities. Paeciureallin (1) exhibited moderate cytotoxicity against SW480 and A549 cell lines, and the IC₅₀ values were 32.0 ± 0.1 and 34.4 ± 2.0 μM, respectively.

Complementary Strategies to Unlock Biosynthesis Gene Clusters Encoding Secondary Metabolites in the Filamentous Fungus Podospora anserina

The coprophilous ascomycete Podospora anserina is known to have a high potential to synthesize a wide array of secondary metabolites (SMs). However, to date, the characterization of SMs in this species, as in other filamentous fungal species, is far less than expected by the functional prediction through genome mining, likely due to the inactivity of most SMs biosynthesis gene clusters (BGCs) under standard conditions. In this work, our main objective was to compare the global strategies usually used to deregulate SM gene clusters in P. anserina, including the variation of culture conditions and the modification of the chromatin state either by genetic manipulation or by chemical treatment, and to show the complementarity of the approaches between them. In this way, we showed that the metabolomics-driven comparative analysis unveils the unexpected diversity of metabolic changes in P. anserina and that the integrated strategies have a mutual complementary effect on the expression of the fungal metabolome. Then, our results demonstrate that metabolite production is significantly influenced by varied cultivation states and epigenetic modifications. We believe that the strategy described in this study will facilitate the discovery of fungal metabolites of interest and will improve the ability to prioritize the production of specific fungal SMs with an optimized treatment.

Global regulatory factor AaLaeA upregulates the production of antitumor substances in the endophytic fungus Alternaria alstroemeria

The global regulatory factor LaeA has been shown to be involved in the biosynthesis of secondary metabolites in various fungi. In a previous work, we isolated an endophytic fungus from Artemisia annua, and its extract had a significant inhibitory effect on the A549 cancer cell line. Phylogenetic analysis further identified the strain as Alternaria alstroemeria. Overexpression of AalaeA gene resulted in significantly increased antitumor activity of this strain's extract. The 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay results showed that the inhibition rate of the AalaeA^OE29 mutant extract on A549 cancer cells was significantly higher than that of the WT extract, as the IC₅₀ decreased from 195.0 to 107.4 μg/ml, and the total apoptosis rate was enhanced. Overexpression of the AalaeA gene significantly increased the contents of myricetin, geraniol, ergosterol, and 18 other antitumor compounds as determined by metabolomic analysis. Transcriptomic analysis revealed significant changes in 95 genes in the mutant strain, including polyketide synthases, nonribosomal peptide synthases, cytochrome P450s, glycosyltransferases, acetyl-CoA acetyltransferases, and others. These results suggested that AaLaeA mediated the antitumor activity of the metabolites in A. alstroemeria by regulating multiple metabolic pathways.

The BcLAE1 is involved in the regulation of ABA biosynthesis in Botrytis cinerea TB-31

Abscisic acid (ABA), as a classic plant hormone, is a key factor in balancing the metabolism of endogenous plant hormones, and plays an important role in regulating the activation of mammalian innate immune cells and glucose homeostasis. Currently, Botrytis cinerea has been used for fermentation to produce ABA. However, the mechanism of the regulation of ABA biosynthesis in B. cinerea is still not fully understood. The putative methyltransferase LaeA/LAE1 is a global regulator involved in the biosynthesis of a variety of secondary metabolites in filamentous fungi. In this study, we demonstrated that BcLAE1 plays an important role in the regulation of ABA biosynthesis in B. cinerea TB-31 by knockout experiment. The deletion of Bclae1 caused a 95% reduction in ABA yields, accompanied by a decrease of the transcriptional level of the ABA synthesis gene cluster Bcaba1-4. Further RNA-seq analysis indicated that deletion of Bclae1 also affected the expression level of key enzymes of BOA and BOT in secondary metabolism, and accompanied by clustering regulatory features. Meanwhile, we found that BcLAE1 is involved in epigenetic regulation as a methyltransferase, with enhanced H3K9me3 modification and attenuated H3K4me2 modification in ΔBclae1 mutant, and this may be a strategy for BcLAE1 to regulate ABA synthesis.

Epigenetic Modification: A Key Tool for Secondary Metabolite Production in Microorganisms

Microorganisms are stupendous source of secondary metabolites, having significant pharmaceutical and industrial importance. Genome mining has led to the detection of several cryptic metabolic pathways in the natural producer of secondary metabolites (SMs) such as actinobacteria and fungi. Production of these bioactive compounds in considerable amount is, however, somewhat challenging. This led to the search of using epigenetics as a key mechanism to alter the expression of genes that encode the SMs toward higher production in microorganisms. Epigenetics is defined as any heritable change without involving the changes in the underlying DNA sequences. Epigenetic modifications include chromatin remodeling by histone posttranslational modifications, DNA methylation, and RNA interference. Biosynthetic gene cluster for SMs remains in heterochromatin state in which the transcription of constitutive gene is regulated by epigenetic modification. Therefore, small-molecule epigenetic modifiers, which promote changes in the structure of chromatin, could control the expression of silent genes and may be rationally employed for discovery of novel bioactive compounds. This review article focuses on the types of epigenetic modifications and their impact on gene expression for enhancement of SM production in microorganisms.

Structurally Various Sorbicillinoids From an Endophytic Fungus Acremonium citrinum SS-g13

Three new sorbicillinoids, including trimer trisorbicillinone E (1), acremosorbicillinoids A and B (2 and 3), and a new alkaloid acremokaloid A (4), and a new natural product 2S,3S-acetyl-β-methyltryptophan (5), were isolated from an endophytic fungus Acremonium citrinum SS-g13, which is found in Fructus mori plant root. In addition, eight known sorbicillinoids (6-13) were also obtained. The new compound structures were established using NMR, HRESIMS spectra, and reported spectroscopic data. The absolute configurations of compounds 1-5, were determined by spectroscopic analysis, Snatzke's method, and time-dependent density functional theory-electronic circular dichroism (TDDFT-ECD) calculations. Compound 11 exhibited significant cholesterol efflux enhancing activity. A plausible biosynthesis pathway for the sorbicillinoids is discussed.

Functional characterization of the GATA-type transcription factor PaNsdD in the filamentous fungus Podospora anserina and its interplay with the sterigmatocystin pathway

The model ascomycete Podospora anserina, distinguished by its strict sexual development, is a prolific but yet unexploited reservoir of natural products. The GATA-type transcription factor NsdD has been characterized by the role in balancing asexual and sexual reproduction and governing secondary metabolism in filamentous fungi. In the present study, we functionally investigated the NsdD ortholog PaNsdD in P. anserina. Compared to the wild-type strain, vegetative growth, ageing processes, sexual reproduction, stress tolerance, and interspecific confrontations in the mutant were drastically impaired, owing to the loss of function of PaNsdD. In addition, the production of 3-acetyl-4-methylpyrrole, a new metabolite identified in P. anserina in this study, was significantly inhibited in the ΔPaNsdD mutant. We also demonstrated the interplay of PaNsdD with the sterigmatocystin biosynthetic gene pathway, especially as the deletion of PaNsdD triggered the enhanced red-pink pigment biosynthesis that occurs only in the presence of the core polyketide synthase-encoding gene PaStcA of the sterigmatocystin pathway. Taken together, these results contribute to a better understanding of the global regulation mediated by PaNsdD in P. anserina, especially with regard to its unexpected involvement in the fungal ageing process and its interplay with the sterigmatocystin pathway.

IMPORTANCE Fungal transcription factors play an essential role in coordinating multiple physiological processes. However, little is known about the functional characterization of transcription factors in the filamentous fungus Podospora anserina. In this study, a GATA-type regulator PaNsdD was investigated in P. anserina. The results showed that PaNsdD was a key factor that can control the fungal ageing process, vegetative growth, pigmentation, stress response, and interspecific confrontations and positively regulate the production of 3-acetyl-4-methylpyrrole. Meanwhile, a molecular interaction was implied between PaNsdD and the sterigmatocystin pathway. Overall, loss of function of PaNsdD seems to be highly disadvantageous for P. anserina, which relies on pure sexual reproduction in a limited life span. Therefore, PaNsdD is clearly indispensable for the survival and propagation of P. anserina in its complex ecological niches.

Recent Advances in Sorbicillinoids from Fungi and Their Bioactivities (Covering 2016–2021)

Sorbicillinoids are a family of hexaketide metabolites with a characteristic sorbyl side chain residue. Sixty-nine sorbicillinoids from fungi, newly identified from 2016 to 2021, are summarized in this review, including their structures and bioactivities. They are classified into monomeric, dimeric, trimeric, and hybrid sorbicillinoids according to their basic structural features, with the main groups comprising both monomeric and dimeric sorbicillinoids. Some of the identified sorbicillinoids have special structures such as ustilobisorbicillinol A, and sorbicillasins A and B. The majority of sorbicillinoids have been reported from fungi genera such as Acremonium, Penicillium, Trichoderma, and Ustilaginoidea, with some sorbicillinoids exhibiting cytotoxic, antimicrobial, anti-inflammatory, phytotoxic, and α-glucosidase inhibitory activities. In recent years, marine-derived, extremophilic, plant endophytic, and phytopathogenic fungi have emerged as important resources for diverse sorbicillinoids with unique skeletons. The recently revealed biological activities of sorbicillinoids discovered before 2016 are also described in this review.

Isolation and Characterization of Anti-Inflammatory Sorbicillinoids from the Mangrove-Derived Fungus Penicillium sp. DM815

Marine derived fungus has gained increasing ground in the discovery of novel lead compounds with potent biological activities including anti-inflammation. Here, we first report the characterization of one new sorbicillinoid (1) and fourteen known compounds (2-15) from the ethyl acetate (AcOEt) extract of a cultured mangrove derived fungus Penicillium sp. DM815 by UV, IR, HR ESI-Q-TOF MS, and NMR spectra. We then evaluated the anti-inflammatory effects of eleven sorbicillinoids (1-11) using cultured macrophage RAW264.7 cells. The results show that compound 9, and to a lesser degree compound 5, significantly inhibited the Gram-negative bacteria lipopolysaccharide (LPS)-induced upregulation of the inducible nitric oxide synthase (iNOS). Consistently, compounds 5 and 9 significantly reduced the level of nitric oxide (NO), the product of iNOS, induced by LPS. We further show that these two compounds dose-dependently inhibited LPS-triggered iNOS expression and NO production, but had no effect on proliferation of RAW264.7 cells in the presence of LPS. In conclusion, our study identifies novel and known sorbicillinoids as potent anti-inflammatory agents, holding the promise of developing novel anti-inflammation treatment in the future.

Marine natural products

This review covers the literature published in 2019 for marine natural products (MNPs), with 719 citations (701 for the period January to December 2019) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1490 in 440 papers for 2019), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. Methods used to study marine fungi and their chemical diversity have also been discussed.

Structurally various sorbicillinoids from the deep-sea sediment derived fungus Penicillium sp. SCSIO06871

Two new hybrid sorbicillinoids (1 and 5), three new bisorbicillinoids (2-4), and three monomeric sorbicillinoids (6-8), along with eighteen known sorbicillinoids (9-26) were isolated from cultures of the deep-sea sediment derived fungus Penicillium sp. SCSIO06871. Their structures and absolute configurations were elucidated based upon the extensive spectroscopic analysis, X-ray crystallography analysis and the comparison of the experimental and calculated ECD data. Bisorbicillpyrone A (4) is the first example of bisorbicillinoid containing an α-pyrone derivative unit. All of the isolated compounds were evaluated for their antibacterial, antifungal and enzyme inhibitory activities against α-glycosidase and acetylcholinesterase (AChE) in vitro. Compound 6 displayed more potent inhibitory activity against α-glycosidase than acarbose with IC₅₀ value of 36.0 μM and compounds 4, 12, 18, 22, 23 exhibited moderate inhibitory activity with IC₅₀ values ranging from 115.8 to 208.5 μM. Compounds 10 and 22 showed weak enzyme inhibitory activities against AChE with 55.1% and 51.1% inhibitions at concentration of 50 μg/mL, respectively. Besides, compounds 11 and 12 exhibited significant antibacterial activities against Staphylococcus aureus with MIC values of 10.0 and 5.0 μg/mL, respectively. The hypothetical biosynthetic pathway of the isolated sorbicillinoids with three different structural types was discussed.

Overexpression of Global Regulator Talae1 Leads to the Discovery of New Antifungal Polyketides From Endophytic Fungus Trichoderma afroharzianum

Transcription regulation caused by global regulators exerts important effects on fungal secondary metabolism. By overexpression of the global regulator Talae1 in a Ficus elastica-associated fungus Trichoderma afroharzianum, two structurally new polyketides (1 and 2) that were newly produced in the transformant were isolated and identified. Their structures, including the absolute configurations, were elucidated through a combination of high resolution mass spectrometer (HRMS), NMR, and electronic circular dichroism (ECD) calculations. The growth inhibitory activities of compounds 1 and 2 were evaluated against four bacteria and six plant-pathogenic fungi. Compound 1 showed the highest antifungal activity against Botrytis cinerea and Fusarium oxysporum f. sp. nicotianae with MIC of 8 μg/ml. To the best of our knowledge, this is the first study to report on the application of the global regulator in T. afroharzianum to activate the biosynthesis of bioactive secondary metabolites.

Heteroexpression of Aspergillus nidulans laeA in Marine-Derived Fungi Triggers Upregulation of Secondary Metabolite Biosynthetic Genes

Fungi are a prospective resource of bioactive compounds, but conventional methods of drug discovery are not effective enough to fully explore their metabolic potential. This study aimed to develop an easily attainable method to elicit the metabolic potential of fungi using Aspergillus nidulans laeA as a transcription regulation tool. In this study, functional analysis of Aspergillus nidulans laeA (AnLaeA) and Aspergillus sp. Z5 laeA (Az5LaeA) was done in the fungus Aspergillus sp. Z5. Heterologous AnLaeA-and native Az5LaeA-overexpression exhibited similar phenotypic effects and caused an increase in production of a bioactive compound diorcinol in Aspergillus sp. Z5, which proved the conserved function of this global regulator. In particular, heteroexpression of AnLaeA showed a significant impact on the expression of velvet complex genes, diorcinol synthesis-related genes, and different transcription factors (TFs). Moreover, heteroexpression of AnLaeA influenced the whole genome gene expression of Aspergillus sp. Z5 and triggered the upregulation of many genes. Overall, these findings suggest that heteroexpression of AnLaeA in fungi serves as a simple and easy method to explore their metabolic potential. In relation to this, AnLaeA was overexpressed in the fungus Penicillium sp. LC1-4, which resulted in increased production of quinolactacin A.

Regulation of Secondary Metabolism in the Penicillium Genus

Penicillium, one of the most common fungi occurring in a diverse range of habitats, has a worldwide distribution and a large economic impact on human health. Hundreds of the species belonging to this genus cause disastrous decay in food crops and are able to produce a varied range of secondary metabolites, from which we can distinguish harmful mycotoxins. Some Penicillium species are considered to be important producers of patulin and ochratoxin A, two well-known mycotoxins. The production of these mycotoxins and other secondary metabolites is controlled and regulated by different mechanisms. The aim of this review is to highlight the different levels of regulation of secondary metabolites in the Penicillium genus.

Genome Mining and Synthetic Biology in Marine Natural Product Discovery

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Sorbicillinoid Derivatives From Sponge-Derived Fungus Trichoderma reesei (HN-2016-018)

Six new sorbicillinoids, trichoreeseione A (1) and B (2), trichodermolide B (3), 13-hydroxy-trichodermolide (4), 24-hydroxy-trichodimerol (5), 15-hydroxy-bisvertinol (7), together with three known analogs, trichodimerol (6), 24-hydroxy-bisvertinol (8), and bisvertinol (9), were isolated from the sponge-derived fungus Trichoderma reesei (HN-2016-018). Their structures including absolute configurations were elucidated by analysis of NMR, MS data, and calculated ECD spectra. Compounds 1 and 2 with a characteristic naphthalene-trione ring were firstly reported in sorbicillinoid family. Compounds 3 and 4 were two rare sorbicillinoids containing a unique bicycle [3.2.1] lactone skeleton, while 3 with a propan-2-one moiety was also recorded first time in this family. Compound 5 displayed cytotoxic activity against A549, MCF-7, and HCT116 cell lines with the IC₅₀ values of 5.1, 9.5, and 13.7 μM, respectively.

Epigenetic manipulation of filamentous fungi for biotechnological applications: a systematic review

The study of the epigenetic regulation of gene function has reached pivotal importance in life sciences in the last decades. The mechanisms and effects of processes such as DNA methylation, histone posttranslational modifications and non-coding RNAs, as well as their impact on chromatin structure and dynamics, are clearly involved in physiology homeostasis in plants, animals and microorganisms. In the fungal kingdom, studies on the model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe contributed enormously to the elucidation of the eukaryote epigenetic landscape. Epigenetic regulation plays a central role in the expression of virulence attributes of human pathogens such as Candida albicans. In this article, we review the most recent studies on the effects of drugs capable of altering epigenetic states and on the impact of chromatin structure-related genes deletion in filamentous fungi. Emphasis is given on plant and insect pathogens, endophytes, secondary metabolites and cellulases/xylanases producing species.