Enhancing the Production of the Fungal Pigment Aurofusarin in Fusarium graminearum

Mutual interaction of the entomopathogenic and endophytic fungus Metarhizium anisopliae with zearalenone as a native component of crude Fusarium extract

The present study revealed the consequences of the interaction of a widely used bioinsecticide and endophyte Metarhizium anisopliae with the hazardous mycotoxin zearalenone (ZEN) as a pure substance and with ZEN as a native component of a crude Fusarium extract. In the environment, microorganisms encounter a mixture of metabolites secreted by other organisms living in the same area, not single substances. The obtained results suggest that M. anisopliae, exposed to a variety of active substances produced by Fusarium graminearum, is able to eliminate ZEN. Within 14 days, M. anisopliae biotransformed 90.8% and 85.8% of ZEN as a pure substance and ZEN as a native component of the F. graminearum extract from Rice Medium (E-Fg-RM), respectively, through reduction predominantly to α-epimers of zearalenols and zearalanols, considered more estrogenic than ZEN, which can raise concerns. Compared to pure ZEN, E-Fg-RM significantly affected the production of Metarhizium secondary metabolites by increasing the destruxins amount by approximately 20-25% and reducing the swainsonine content by 96.2%. All these findings provide a possible picture of the interaction of M. anisopliae with ZEN in the wild, mainly as a result of the use of crude extract from Fusarium, which contained a mixture of different metabolites.

Unveiling the Bioprospecting Efficacy and Textile Dyeing of a Novel Endophytic Mycobial Red Pigment

Natural pigments are becoming increasingly popular owing of their reliability. Microbial pigments provide an alternative to natural colours. A total of 24 fungal cultures were collected from leaf bits of Senna auriculata, with one strain (FNG1) producing an extracellular red orange pigment. Nigrospora oryzae was confirmed by using physical criteria and molecular phylogenetic study by using ITS and β- tubulin analysis. In EtOAc, the crude red pigment was the most soluble. The TLC analysis was used to partly purify the natural pigment. The partially purified fungal pigment was used in successive bioprospecting studies. The antimicrobial activity of the partially purified sample was assessed against eight human pathogens, with Leucobacter AA7 showing the largest zone of inhibition (200-500 µg/mL). The compound's DPPH scavenging activity enhanced from 38.2 to 67.9%, with an IC50 value of 34.195 ± 2.33 µg/mL. Cancer cells were suppressed by partly pure fungal pigment, but non-cancerous HEK 293 cells were unaffected. The GC-MS analysis was used to characterize the molecule present in the partly purified pigment. In addition, the cotton textiles have the greatest staining capability for crude mycobial pigment, which dyes quickly and has a negative cytotoxicity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-024-01211-y.

A Prototype Method for the Detection and Recognition of Pigments in the Environment Based on Optical Property Simulation

The possibility of pigment detection and recognition in different environments such as solvents or proteins is a challenging, and at the same time demanding, task. It may be needed in very different situations: from the nondestructive in situ identification of pigments in paintings to the early detection of fungal infection in major agro-industrial crops and products. So, we propose a prototype method, the key feature of which is a procedure analyzing the lineshape of a spectrum. The shape of the absorption spectrum corresponding to this transition strongly depends on the immediate environment of a pigment and can serve as a marker to detect the presence of a particular pigment molecule in a sample. Considering carotenoids as an object of study, we demonstrate that the combined operation of the differential evolution algorithm and semiclassical quantum modeling of the optical response based on a generalized spectral density (the number of vibronic modes is arbitrary) allows us to distinguish quantum models of the pigment for different solvents. Moreover, it is determined that to predict the optical properties of monomeric pigments in protein, it is necessary to create a database containing, for each pigment, in addition to the absorption spectra measured in a predefined set of solvents, the parameters of the quantum model found using differential evolution.

Colored stains: Microbial survey of cellulose-based and lignin rich papers

During the centuries diverse types of paper were produced and were characterized by a different ratio of natural macromolecules, mainly lignin and cellulose. Handmade paper has a higher content of cellulose respect to the early machine-made paper, where the lignin is the other important component. Microorganisms are able to colonize and deteriorate both types of papers. They can release on their surfaces pigments and colorants which produced anesthetic stains. The microbiota colonising 17 stains on handmade and machine-made paper surfaces together with that in library and archive environments was analyzed. Combination of microbiological and high-throughput sequencing (HTS) approaches were applied. The culture-dependent methodology comprised: isolation, DNA identification, hydrolytic and paper staining assays. The HTS was performed by MinION platform and for the mycobiome a more suitable bioinformatics analysis pipeline, MetONTIIME based on QIIME2 framework, was applied. The paper model staining assay permitted the direct recognition of colorizing isolates which in combination with sequencing data evidenced a complex microbial community able to stain the two types of paper. Staining abilities were confirmed by frequently isolated and detected fungi and also by new ones such as Roussoella euonymi and Achaetomium. We have also evidenced the staining ability of several bacteria.

The Genome of Fusarium oxysporum f. sp. phaseoli Provides Insight into the Evolution of Genomes and Effectors of Fusarium oxysporum Species

Fusarium oxysporum f. sp. phaseoli, the causal agent of cowpea fusarium wilt, is a serious threat to cowpea production in China. In this study, a sample of cowpea fusarium wilt was identified as Fusarium oxysporum f. sp. phaseoli using the methods of morphological characters and molecular detection. We further reported the first genome assembly for Fusarium oxysporum f. sp. phaseoli, with 53.7 Mb genome sequence comprising 14,694 genes. Comparative genomic analysis among five Fusarium oxysporum genomes showed that four accessory chromosomes in the five Fusarium oxysporum display similar characteristics, with low sequence similarity (55.35%, vs. overall average of 81.76%), low gene density (2.18 genes/10 kb vs. 3.02 genes/Mb) and highly transposable element density (TEs) (15.01/100 kb vs. 4.89/100 kb), indicating that variable accessory chromosomes are the main source of Fusarium oxysporum evolution. We identified a total of 100 Fusarium oxysporum f. sp. phaseoli-specific effectors in the genome and found 13 specific effector genes located in large insertion or deletion regions, suggesting that insertion or deletion events can cause the emergence of species-specific effectors in Fusarium oxysporum. Our genome assembly of Fusarium oxysporum f. sp. phaseoli provides a valuable resource for the study of cowpea fusarium wilt, and the comparative genomic study of Fusarium oxysporum could contribute to the knowledge of genome and effector-associated pathogenicity evolution in Fusarium oxysporum study.

Ascomycota as a source of natural colorants

In the last few decades, there has been a great demand for natural colorants. Synthetic colorants are known to be easy to produce, are less expensive, and remain stable when subjected to chemical and physical factors. In addition, only small amounts are required to color any material, and unwanted flavors and aromas are not incorporated into the product. Natural colorants present in food, in addition to providing color, also have biological properties and effects that aid in the prevention and cure of many diseases. The main classes of colorants produced by phylum Ascomycota include polyketides and carotenoids. A promising producer of colorants should be able to assimilate a variety of sources of carbon and nitrogen and also exhibit relative stability. The strain should not be pathogenic, and its product should not be toxic. Production processes should also provide the expected color with a good yield through simple extraction methods. Research that seeks new sources of these compounds should continue to seek products of biotechnological origin in order to be competitive with products of synthetic and plant origin. In this review, we will focus on the recent studies on the main producing species, classes, and metabolic pathways of colorants produced by this phylum, historical background, impact of synthetic colorants on human health and the environment, social demand for natural colorants and also an in-depth approach to bioprocesses (influences on production, optimization of bioprocess, extraction, and identification), and limitations and perspectives for the use of fungal-based dyes.

Phylogenetic Diversity and Mycotoxin Potential of Emergent Phytopathogens Within the Fusarium tricinctum Species Complex

Recent studies on multiple continents indicate members of the Fusarium tricinctum species complex (FTSC) are emerging as prevalent pathogens of small-grain cereals, pulses, and other economically important crops. These understudied fusaria produce structurally diverse mycotoxins, among which enniatins (ENNs) and moniliformin (MON) are the most frequent and of greatest concern to food and feed safety. Herein a large survey of fusaria in the Fusarium Research Center and Agricultural Research Service culture collections was undertaken to assess species diversity and mycotoxin potential within the FTSC. A 151-strain collection originating from diverse hosts and substrates from different agroclimatic regions throughout the world was selected from 460 FTSC strains to represent the breadth of FTSC phylogenetic diversity. Evolutionary relationships inferred from a five-locus dataset, using maximum likelihood and parsimony, resolved the 151 strains as 24 phylogenetically distinct species, including nine that are new to science. Of the five genes analyzed, nearly full-length phosphate permease sequences contained the most phylogenetically informative characters, establishing its suitability for species-level phylogenetics within the FTSC. Fifteen of the species produced ENNs, MON, the sphingosine analog 2-amino-14,16-dimethyloctadecan-3-ol (AOD), and the toxic pigment aurofusarin (AUR) on a cracked corn kernel substrate. Interestingly, the five earliest diverging species in the FTSC phylogeny (i.e., F. iranicum, F. flocciferum, F. torulosum, and Fusarium spp. FTSC 8 and 24) failed to produce AOD and MON, but synthesized ENNs and/or AUR. Moreover, our reassessment of nine published phylogenetic studies on the FTSC identified 11 additional novel taxa, suggesting this complex comprises at least 36 species.

Speed dating for enzymes! Finding the perfect phosphopantetheinyl transferase partner for your polyketide synthase

The biosynthetic pathways for the fungal polyketides bikaverin and bostrycoidin, from Fusarium verticillioides and Fusarium solani respectively, were reconstructed and heterologously expressed in S. cerevisiae alongside seven different phosphopantetheinyl transferases (PPTases) from a variety of origins spanning bacterial, yeast and fungal origins. In order to gauge the efficiency of the interaction between the ACP-domains of the polyketide synthases (PKS) and PPTases, each were co-expressed individually and the resulting production of target polyketides were determined after 48 h of growth. In co-expression with both biosynthetic pathways, the PPTase from Fusarium verticillioides (FvPPT1) proved most efficient at producing both bikaverin and bostrycoidin, at 1.4 mg/L and 5.9 mg/L respectively. Furthermore, the remaining PPTases showed the ability to interact with both PKS's, except for a single PKS-PPTase combination. The results indicate that it is possible to boost the production of a target polyketide, simply by utilizing a more optimal PPTase partner, instead of the commonly used PPTases; NpgA, Gsp and Sfp, from Aspergillus nidulans, Brevibacillus brevis and Bacillus subtilis respectively.

Targeted Genetic Engineering via Agrobacterium-Mediated Transformation in Fusarium solani

Members of the Fusarium solani species complex are filamentous fungi that can act as pathogens to many crops and animals. Although relevant, a robust molecular toolbox is missing for the investigation of gene function and metabolism. In this chapter, we describe how Agrobacterium-mediated transformation can be used to facilitate gene targeting. A flexible vector system, based on in vivo recombination in Saccharomyces cerevisiae, is utilized to achieve overexpression and gene deletion of targeted biosynthetic genes in F. solani f. sp. pisi.

The sustainable cycle of a new cacao-based bioplastic: from manufacturing to exploitable biodegradation products

The exponential growth of plastic consumption in the last decade became a large economic and ecological issue; therefore, strategies have been used to mitigate the environmental impacts, including the manufacture of biodegradable bio-based plastics and biodegradation strategies. Herein, a new bio-based plastic was developed consisting of a polymeric recyclable matrix (polyethylene or polypropylene) with a vegetal polymeric material from cocoa husk. Mechanical and rheological properties were evaluated and the new material showed interesting tensile strength compared to completely non-biodegradable plastics. The new polymeric material was submitted to biodegradation processes using different fungi species. The biodegradation caused by Colletotrichum gloeosporioides, Xylaria sp. and Fusarium graminearum in the new polymeric material was analyzed through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and tensile tests. Furthermore, ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) and mass spectrometry imaging (MSI) were applied to identify metabolites produced in consequence to the biodegradation process. Interestingly, some compounds produced present high economic value.

S-adenosyl-L-homocysteine hydrolase FgSah1 is required for fungal development and virulence in Fusarium graminearum

The S-adenosyl-L-homocysteine hydrolase (Sah1) plays a crucial role in methylation and lipid metabolism in yeast and mammals, yet its function remains elusive in filamentous fungi. In this study, we characterized Sah1 in the phytopathogenic fungus F. graminearum by generating knockout and knockout-complemented strains of FgSAH1. We found that the FgSah1-GFP fusion protein was localized to the cytoplasm, and that deletion of FgSAH1 resulted in defects in vegetative growth, asexual and sexual reproduction, stress responses, virulence, lipid metabolism, and tolerance against fungicides. Moreover, the accumulations of S-adenosyl-L-homocysteine (AdoHcy) and S-adenosyl-L-methionine (AdoMet) (the methyl group donor in most methyl transfer reactions) in ΔFgSah1 were seven- and ninefold higher than those in the wild-type strain, respectively. All of these defective phenotypes in ΔFgSah1 mutants were rescued by target gene complementation. Taken together, these results demonstrate that FgSah1 plays essential roles in methylation metabolism, fungal development, full virulence, multiple stress responses, lipid metabolism, and fungicide sensitivity in F. graminearum. To our knowledge, this is the first report on the systematic functional characterization of Sah1 in F. graminearum.

Production and Selectivity of Key Fusarubins from Fusarium solani due to Media Composition

Natural products display a large structural variation and different uses within a broad spectrum of industries. In this study, we investigate the influence of carbohydrates and nitrogen sources on the production and selectivity of production of four different polyketides produced by Fusarium solani, fusarubin, javanicin, bostrycoidin and anhydrofusarubin. We introduce four different carbohydrates and two types of nitrogen sources. Hereafter, a full factorial design was applied using combinations of three levels of sucrose and three levels of the two types of nitrogen. Each combination displayed different selectivity and production yields for all the compounds of interest. Response surface design was utilized to investigate possible maximum yields for the surrounding combinations of media. It was also shown that the maximum yields were not always the ones illustrating high selectivity, which is an important factor for making purification steps easier. We visualized the production over time for one of the media types, illustrating high yields and selectivity.

Trichoderma harzianum metabolites disturb Fusarium culmorum metabolism: Metabolomic and proteomic studies

Trichoderma species are well known for producing various secondary metabolites in response to different fungal pathogens. This paper reports the effects of the metabolites produced during one-day cultivation of Trichoderma harzianum on the growth and development of the popular pathogen Fusarium culmorum. Inhibition of the growth of the pathogen and production of secondary metabolites including zearalenone was observed on Petri dishes. The presence of proteins such as cytochrome c oxidase subunit 4, glutathione-independent glyoxalase HSP31, and putative peroxiredoxin pmp20 in the extract-treated culture indicated oxidative stress, which was confirmed by the presence of a higher amount of catalase and dismutase in the later hours of the culture. A larger amount of enolase and glyceraldehyde 3-phosphate dehydrogenase resulted in faster growth, and the overexpression of stress protein and Woronin body major protein indicated the activation of defense mechanisms. In addition, a cardinal reduction in major mycotoxin production was noted.

Heterologous Expression of the Core Genes in the Complex Fusarubin Gene Cluster of Fusarium Solani

Through stepwise recreation of the biosynthetic gene cluster containing PKS3 from Fusarium solani, it was possible to produce the core scaffold compound of bostrycoidin, a red aza-anthraquinone pigment in Saccharomyces cerevisiae. This was achieved through sequential transformation associated recombination (TAR) cloning of FvPPT, fsr1, fsr2, and fsr3 into the pESC-vector system, utilizing the inducible bidirectional galactose promoter for heterologous expression in S. cerevisiae. The production of the core metabolite bostrycoidin was investigated through triplicate growth cultures for 1-4 days, where the maximum titer of bostrycoidin was achieved after 2 days of induction, yielding 2.2 mg/L.

The ADP-ribosylation factor-like small GTPase FgArl1 participates in growth, pathogenicity and DON production in Fusarium graminearum

Fusarium graminearum is the main pathogen of Fusarium head blight (FHB) in wheat and related species, which causes serious production decreases and economic losses and produces toxins such as deoxynivalenol (DON), which endangers the health of humans and livestock. Vesicle transport is a basic physiological process required for cell survival in eukaryotes. Many regulators of vesicle transport are reported to be involved in the pathogenicity of fungi. In yeast and mammalian cells, the ADP-ribosylation factor-like small GTPase Arl1 and its orthologs are involved in regulating vesicular trafficking, cytoskeletal reorganization and other significant biological processes. However, the role of Arl1 in F. graminearum is not well understood. In this study, we characterized the Arl1-homologous protein FgArl1 in F. graminearum and showed that FgArl1 is located in the trans-Golgi apparatus. The deletion of FgARL1 resulted in a significant decrease in vegetative growth and pathogenicity. Further analyses of the ΔFgarl1 mutant revealed defects in the production of DON. Taken together, these results indicate that FgArl1 is important in the development and pathogenicity of F. graminearum.

Fungal Pigments: Potential Coloring Compounds for Wide Ranging Applications in Textile Dyeing

Synthetic pigments/non-renewable coloring sources used normally in the textile industry release toxic substances into the environment, causing perilous ecological challenges. To be safer from such challenges of synthetic colorants, academia and industries have explored the use of natural colorants such as microbial pigments. Such explorations have created a fervent interest among textile stakeholders to undertake the dyeing of textile fabrics, especially with fungal pigments. The biodegradable and sustainable production of natural colorants from fungal sources stand as being comparatively advantageous to synthetic dyes. The prospective scope of fungal pigments has emerged in the opening of many new avenues in textile colorants for wide ranging applications. Applying the biotechnological processes, fungal pigments like carotenoids, melanins, flavins, phenazines, quinones, monascins, violacein, indigo, etc. could be extracted on an industrial scale. This review appraises the studies and applications of various fungal pigments in dyeing textile fabrics and is furthermore shedding light on the importance of toxicity testing, genetic manipulations of fungal pigments, and their future perspectives under biotechnological approaches.

The Dynamin-Like GTPase FgSey1 Plays a Critical Role in Fungal Development and Virulence in Fusarium graminearum

Fusarium graminearum, the main pathogenic fungus causing Fusarium head blight (FHB), produces deoxynivalenol (DON), a key virulence factor, which is synthesized in the endoplasmic reticulum (ER). Sey1/atlastin, a dynamin-like GTPase protein, is known to be required for homotypic fusion of ER membranes, but the functions of this protein are unknown in pathogenic fungi. Here, we characterized Sey1/atlastin homologue FgSey1 in F. graminearum Like Sey1/atlastin, FgSey1 is located in the ER. The FgSEY1 deletion mutant exhibited significantly reduced vegetative growth, asexual development, DON biosynthesis, and virulence. Moreover, the ΔFgsey1 mutant was impaired in the formation of normal lipid droplets (LDs) and toxisomes, both of which participate in DON biosynthesis. The GTPase, helix bundle (HB), transmembrane segment (TM), and cytosolic tail (CT) domains of FgSey1 are essential for its function, but only the TM domain is responsible for its localization. Furthermore, the mutants FgSey1^K63A and FgSey1^T87A lacked GTPase activity and failed to rescue the defects of the ΔFgsey1 mutant. Collectively, our data suggest that the dynamin-like GTPase protein FgSey1 affects the generation of LDs and toxisomes and is required for DON biosynthesis and pathogenesis in F. graminearum IMPORTANCE Fusarium graminearum is a major plant pathogen that causes Fusarium head blight (FHB) of wheats worldwide. In addition to reducing the plant yield, F. graminearum infection of wheats also results in the production of deoxynivalenol (DON) mycotoxins, which are harmful to humans and animals and therefore cause great economic losses through pollution of food products and animal feed. At present, effective strategies for controlling FHB are not available. Therefore, understanding the regulation mechanisms of fungal development, pathogenesis, and DON biosynthesis is important for the development of effective control strategies of this disease. In this study, we demonstrated that a dynamin-like GTPase protein Sey1/atlastin homologue, FgSey1, is required for vegetative growth, DON production, and pathogenicity in F. graminearum Our results provide novel information on critical roles of FgSey1 in fungal pathogenicity; therefore, FgSey1 could be a potential target for effective control of the disease caused by F. graminearum.

A new vector system for targeted integration and overexpression of genes in the crop pathogen Fusarium solani

Background

Besides their ability to produce several interesting bioactive secondary metabolites, members of the Fusarium solani species complex comprise important pathogens of plants and humans. One of the major obstacles in understanding the biology of this species complex is the lack of efficient molecular tools for genetic manipulation.

Results

To remove this obstacle we here report the development of a reliable system where the vectors are generated through yeast recombinational cloning and inserted into a specific site in F. solani through Agrobacterium tumefaciens-mediated transformation. As proof-of-concept, the enhanced yellow fluorescent protein (eYFP) was inserted in a non-coding genomic position of F. solani and subsequent analyses showed that the resulting transformants were fluorescent on all tested media. In addition, we cloned and overexpressed the Zn(II)₂Cys₆ transcriptional factor fsr6 controlling mycelial pigmentation. A transformant displayed deep red/purple pigmentation stemming from bostrycoidin and javanicin.

Conclusion

By creating streamlined plasmid construction and fungal transformation systems, we are now able to express genes in the crop pathogen F. solani in a reliable and fast manner. As a case study, we targeted and activated the fusarubin (PKS3: fsr) gene cluster, which is the first case study of secondary metabolites being directly associated with the responsible gene cluster in F. solani via targeted activation. The system provides an approach that in the future can be used by the community to understand the biochemistry and genetics of the Fusarium solani species complex, and is obtainable from Addgene catalog #133094.

Graphic abstract

Fungal Pigments and Their Prospects in Different Industries

The public's demand for natural, eco-friendly, and safe pigments is significantly increasing in the current era. Natural pigments, especially fungal pigments, are receiving more attention and seem to be in high demand worldwide. The immense advantages of fungal pigments over other natural or synthetic pigments have opened new avenues in the market for a wide range of applications in different industries. In addition to coloring properties, other beneficial attributes of fungal pigments, such as antimicrobial, anticancer, antioxidant, and cytotoxic activity, have expanded their use in different sectors. This review deals with the study of fungal pigments and their applications and sheds light on future prospects and challenges in the field of fungal pigments. Furthermore, the possible application of fungal pigments in the textile industry is also addressed.