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J. Fungi, Volume 6, Issue 3 (September 2020) – 90 articles

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Cover Story (view full-size image) Sporulation in Ashbya gossypii is regulated by a set of conserved regulators that drive the [...] Read more.
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Open AccessReview
Echinocandins as Biotechnological Tools for Treating Candida auris Infections
J. Fungi 2020, 6(3), 185; https://doi.org/10.3390/jof6030185 - 22 Sep 2020
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Abstract
Candida auris has been reported in the past few years as an invasive fungal pathogen of high interest. Its recent emergence in healthcare-associated infections triggered the efforts of researchers worldwide, seeking additional alternatives to the use of traditional antifungals such as azoles. Lipopeptides, [...] Read more.
Candida auris has been reported in the past few years as an invasive fungal pathogen of high interest. Its recent emergence in healthcare-associated infections triggered the efforts of researchers worldwide, seeking additional alternatives to the use of traditional antifungals such as azoles. Lipopeptides, specially the echinocandins, have been reported as an effective approach to control pathogenic fungi. However, despite its efficiency against C. auris, some isolates presented echinocandin resistance. Thus, therapies focused on echinocandins’ synergism with other antifungal drugs were widely explored, representing a novel possibility for the treatment of C. auris infections. Full article
(This article belongs to the Special Issue Antifungal Peptides 2020)
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Open AccessArticle
Designed Antimicrobial Peptides Against Trauma-Related Cutaneous Invasive Fungal Wound Infections
J. Fungi 2020, 6(3), 184; https://doi.org/10.3390/jof6030184 - 22 Sep 2020
Viewed by 347
Abstract
Cutaneous invasive fungal wound infections after life-threatening dismounted complex blast injury (DCBI) and natural disasters complicate clinical care. These wounds often require aggressive repeated surgical debridement, can result in amputations and hemipelvectomies and have a 38% mortality rate. Given the substantial morbidity associated [...] Read more.
Cutaneous invasive fungal wound infections after life-threatening dismounted complex blast injury (DCBI) and natural disasters complicate clinical care. These wounds often require aggressive repeated surgical debridement, can result in amputations and hemipelvectomies and have a 38% mortality rate. Given the substantial morbidity associated with cutaneous fungal wound infections, patients at risk need immediate empiric treatment mandating the use of rapidly acting broad-spectrum antimicrobials, acting on both fungi and bacteria, that are also effective against biofilm and can be administered topically. Designed antimicrobial peptides (dAMPs) are engineered analogues of innate antimicrobial peptides which provide the first line of defense against invading pathogens. The antifungal and antibacterial effect and mammalian cytotoxicity of seven innovative dAMPs, created by iterative structural analog revisions and physicochemical and functional testing were investigated. The dAMPs possess broad-spectrum antifungal activity, in addition to being effective against Gram-negative and Gram-positive bacteria, which is crucial as many wounds are polymicrobial and require immediate empiric treatment. Three of the most potent dAMPs—RP504, RP556 and RP557—possess limited mammalian cytotoxicity following 8 h incubation. If these encouraging broad-spectrum antimicrobial and rapid acting results are translated clinically, these novel dAMPs may become a first line empiric topical treatment for traumatic wound injuries. Full article
(This article belongs to the Special Issue Antifungal Peptides 2020)
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Open AccessArticle
In Vitro and In Vivo Inhibitory Activity of Limonene against Different Isolates of Candida spp.
J. Fungi 2020, 6(3), 183; https://doi.org/10.3390/jof6030183 - 22 Sep 2020
Viewed by 660
Abstract
Commensal yeast from the genus Candida is part of the healthy human microbiota. In some cases, Candida spp. dysbiosis can result in candidiasis, the symptoms of which may vary from mild localized rashes to severe disseminated infections. The most prevalent treatments against candidiasis [...] Read more.
Commensal yeast from the genus Candida is part of the healthy human microbiota. In some cases, Candida spp. dysbiosis can result in candidiasis, the symptoms of which may vary from mild localized rashes to severe disseminated infections. The most prevalent treatments against candidiasis involve fluconazole, itraconazole, miconazole, and caspofungin. Moreover, amphotericin B associated with prolonged azole administration is utilized to control severe cases. Currently, numerous guidelines recommend echinocandins to treat invasive candidiasis. However, resistance to these antifungal drugs has increased dramatically over recent years. Considering this situation, new therapeutic alternatives should be studied to control candidiasis, which has become a major medical concern. Limonene belongs to the group of terpene molecules, known for their pharmacological properties. In this study, we evaluated in vitro the limonene concentration capable of inhibiting the growth of yeast from the genus Candida susceptible or resistant to antifungal drugs and its capacity to induce fungal damage. In addition, intravaginal fungal infection assays using a murine model infected by Candida albicans were carried out and the fungal burden, histopathology, and scanning electron microscopy were evaluated. All of our results suggest that limonene may play a protective role against the infection process by yeast from the genus Candida. Full article
(This article belongs to the Special Issue Systemic and Emerging Mycoses)
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Open AccessArticle
ATAC-Seq Identifies Chromatin Landscapes Linked to the Regulation of Oxidative Stress in the Human Fungal Pathogen Candida albicans
J. Fungi 2020, 6(3), 182; https://doi.org/10.3390/jof6030182 - 21 Sep 2020
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Abstract
Human fungal pathogens often encounter fungicidal stress upon host invasion, but they can swiftly adapt by transcriptional reprogramming that enables pathogen survival. Fungal immune evasion is tightly connected to chromatin regulation. Hence, fungal chromatin modifiers pose alternative treatment options to combat fungal infections. [...] Read more.
Human fungal pathogens often encounter fungicidal stress upon host invasion, but they can swiftly adapt by transcriptional reprogramming that enables pathogen survival. Fungal immune evasion is tightly connected to chromatin regulation. Hence, fungal chromatin modifiers pose alternative treatment options to combat fungal infections. Here, we present an assay for transposase-accessible chromatin using sequencing (ATAC-seq) protocol adapted for the opportunistic pathogen Candida albicans to gain further insight into the interplay of chromatin accessibility and gene expression mounted during fungal adaptation to oxidative stress. The ATAC-seq workflow not only facilitates the robust detection of genomic regions with accessible chromatin but also allows for the precise modeling of nucleosome positions in C. albicans. Importantly, the data reveal genes with altered chromatin accessibility in upstream regulatory regions, which correlate with transcriptional regulation during oxidative stress. Interestingly, many genes show increased chromatin accessibility without change in gene expression upon stress exposure. Such chromatin signatures could predict yet unknown regulatory factors under highly dynamic transcriptional control. Additionally, de novo motif analysis in genomic regions with increased chromatin accessibility upon H2O2 treatment shows significant enrichment for Cap1 binding sites, a major factor of oxidative stress responses in C. albicans. Taken together, the ATAC-seq workflow enables the identification of chromatin signatures and highlights the dynamics of regulatory mechanisms mediating environmental adaptation of C. albicans. Full article
(This article belongs to the Special Issue Epigenetic Regulation of Fungal Virulence)
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Open AccessArticle
Mycosynthesis of ZnO Nanoparticles Using Trichoderma spp. Isolated from Rhizosphere Soils and Its Synergistic Antibacterial Effect against Xanthomonas oryzae pv. oryzae
J. Fungi 2020, 6(3), 181; https://doi.org/10.3390/jof6030181 - 20 Sep 2020
Viewed by 453
Abstract
The Plant Growth Promoting Fungi (PGPF) is used as a source of biofertilizers due to their production of secondary metabolites and beneficial effects on plants. The present work is focused on the co-cultivation of Trichoderma spp. (T. harzianum (PGT4), T. reesei (PGT5) [...] Read more.
The Plant Growth Promoting Fungi (PGPF) is used as a source of biofertilizers due to their production of secondary metabolites and beneficial effects on plants. The present work is focused on the co-cultivation of Trichoderma spp. (T. harzianum (PGT4), T. reesei (PGT5) and T. reesei (PGT13)) and the production of secondary metabolites from mono and co-culture and mycosynthesis of zinc oxide nanoparticles (ZnO NPs), which were characterized by a UV visible spectrophotometer, Powder X-ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDAX) and Transmission Electron Microscope (TEM) and Selected Area (Electron) Diffraction (SAED) patterns. The fungal secondary metabolite crude was extracted from the mono and co-culture of Trichoderma spp. And were analyzed by GC-MS, which was further subjected for antibacterial activity against Xanthomonas oryzae pv. Oryzae, the causative organism for Bacterial Leaf Blight (BLB) in rice. Our results showed that the maximum zone of inhibition was recorded from the co-culture of Trichoderma spp. rather than mono cultures, which indicates that co-cultivation of beneficial fungi can stimulate the synthesis of novel secondary metabolites better than in monocultures. ZnO NPs were synthesized from fungal secondary metabolites of mono cultures of Trichoderma harzianum (PGT4), Trichoderma reesei (PGT5), Trichoderma reesei (PGT13) and co-culture (PGT4 + PGT5 + PGT13). These ZnO NPs were checked for antibacterial activity against Xoo, which was found to be of a dose-dependent manner. In summary, the biosynthesized ZnO NPs and secondary metabolites from co-culture of Trichoderma spp. are ecofriendly and can be used as an alternative for chemical fertilizers in agriculture. Full article
(This article belongs to the Special Issue Fungal Nanotechnology)
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Open AccessArticle
Stem Endophytic Mycobiota in Wild and Domesticated Wheat: Structural Differences and Hidden Resources for Wheat Improvement
J. Fungi 2020, 6(3), 180; https://doi.org/10.3390/jof6030180 - 18 Sep 2020
Viewed by 393
Abstract
Towards the identification of entophytic fungal taxa with potential for crop improvement, we characterized and compared fungal endophyte communities (FECs) from domesticated bread wheat and two wheat ancestors, Aegilopssharonensis and Triticumdicoccoides. Data generated by next generation sequencing identified a total [...] Read more.
Towards the identification of entophytic fungal taxa with potential for crop improvement, we characterized and compared fungal endophyte communities (FECs) from domesticated bread wheat and two wheat ancestors, Aegilopssharonensis and Triticumdicoccoides. Data generated by next generation sequencing identified a total of 1666 taxa. The FECs in the three plant species contained high proportions of random taxa with low abundance. At plant species level, the majority of abundant taxa were common to all host plants, and the collective FECs of each of the three plant species had similar diversity. However, FECs from the wild plants in specific sites were more diverse and had greater richness than wheat FECs from corresponding specific fields. The wild plants also had higher numbers of differentially abundant fungal taxa than wheat, with Alternaria infectoria being the most abundant species in wild plants and Candida sake the most abundant in wheat. Network analysis on co-occurrence association revealed a small number of taxa with a relatively high number of co-occurrence associations, which might be important in community assembly. Our results show that the actual endophytic cargo in cultivated wheat plants is limited relative to wild plants, and highlight putative functional and hub fungal taxa with potential for wheat improvement. Full article
(This article belongs to the Special Issue Fungal Endophytes in Agriculture and Ecosystems)
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Open AccessArticle
Salt Solution Treatments Trigger Antioxidant Defense Response against Gray Mold Disease in Table Grapes
J. Fungi 2020, 6(3), 179; https://doi.org/10.3390/jof6030179 - 18 Sep 2020
Viewed by 324
Abstract
To obtain a clear understanding of the mode of action of potassium bicarbonate (PB), sodium silicate (SSi) and calcium chelate (CCh) solutions (1%) in inducing resistance to gray mold disease in table grapes, enzymatic and nonenzymatic investigations were carried out. In particular, changes [...] Read more.
To obtain a clear understanding of the mode of action of potassium bicarbonate (PB), sodium silicate (SSi) and calcium chelate (CCh) solutions (1%) in inducing resistance to gray mold disease in table grapes, enzymatic and nonenzymatic investigations were carried out. In particular, changes in the activity of the enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POD), total phenolic content and total flavonoid content were studied. As indirect action, PB, SSi and CCh reduced the incidence of gray mold by 43%, 50% and 41%, respectively. The highest activity of SOD was detected at 48 h in SSi-treated tissue, PB-treated tissue and CCh-treated tissue, and it was 1.7-, 1.4- and 1.2-fold higher, respectively, compared to the control. The APX activity was significantly higher in SSi-treated tissue than in the control at 24, 48 and 72 h and showed an increase in activity 2-fold for all times. Additionally, PB, SSi and CCh increased the activity of POD by 1.4-, 1.2- and 2.7-fold at 48 h posttreatment, respectively. The results showed that CCh was the most pronounced salt to increase both total phenol and flavonoid contents by 1.3 and 2.1, respectively. Additionally, the three tested salts induced an increase in total phenols and total flavonoids at 48 h posttreatment. The obtained result is one more movement towards an overall understanding of the mechanism by which salt solutions act as antimicrobial agents against gray mold of table grapes. Full article
(This article belongs to the Special Issue Plant Fungal Pathogenesis)
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Open AccessArticle
UhAVR1, an HR-Triggering Avirulence Effector of Ustilago hordei, Is Secreted via the ER–Golgi Pathway, Localizes to the Cytosol of Barley Cells during in Planta-Expression, and Contributes to Virulence Early in Infection
J. Fungi 2020, 6(3), 178; https://doi.org/10.3390/jof6030178 - 18 Sep 2020
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Abstract
The basidiomycete Ustilago hordei causes covered smut disease of barley and oats. Virulence effectors promoting infection and supporting pathogen lifestyle have been described for this fungus. Genetically, six avirulence genes are known and one codes for UhAVR1, the only proven avirulence effector identified [...] Read more.
The basidiomycete Ustilago hordei causes covered smut disease of barley and oats. Virulence effectors promoting infection and supporting pathogen lifestyle have been described for this fungus. Genetically, six avirulence genes are known and one codes for UhAVR1, the only proven avirulence effector identified in smuts to date that triggers complete immunity in barley cultivars carrying resistance gene Ruh1. A prerequisite for resistance breeding is understanding the host targets and molecular function of UhAVR1. Analysis of this effector upon natural infection of barley coleoptiles using teliospores showed that UhAVR1 is expressed during the early stages of fungal infection where it leads to HR triggering in resistant cultivars or performs its virulence function in susceptible cultivars. Fungal secretion of UhAVR1 is directed by its signal peptide and occurs via the BrefeldinA-sensitive ER–Golgi pathway in cell culture away from its host. Transient in planta expression of UhAVR1 in barley and a nonhost, Nicotiana benthamiana, supports a cytosolic localization. Delivery of UhAVR1 via foxtail mosaic virus or Pseudomonas species in both barley and N. benthamiana reveals a role in suppressing components common to both plant systems of Effector- and Pattern-Triggered Immunity, including necrosis triggered by Agrobacterium-delivered cell death inducers. Full article
(This article belongs to the Special Issue Smut Fungi)
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Open AccessArticle
Alkaloid Concentrations of Lolium perenne Infected with Epichloë festucae var. lolii with Different Detection Methods—A Re-Evaluation of Intoxication Risk in Germany?
J. Fungi 2020, 6(3), 177; https://doi.org/10.3390/jof6030177 - 18 Sep 2020
Viewed by 424
Abstract
Mycotoxins in agriculturally used plants can cause intoxication in animals and can lead to severe financial losses for farmers. The endophytic fungus Epichloë festucae var. lolii living symbiotically within the cool season grass species Lolium perenne can produce vertebrate and invertebrate toxic alkaloids. [...] Read more.
Mycotoxins in agriculturally used plants can cause intoxication in animals and can lead to severe financial losses for farmers. The endophytic fungus Epichloë festucae var. lolii living symbiotically within the cool season grass species Lolium perenne can produce vertebrate and invertebrate toxic alkaloids. Hence, an exact quantitation of alkaloid concentrations is essential to determine intoxication risk for animals. Many studies use different methods to detect alkaloid concentrations, which complicates the comparability. In this study, we showed that alkaloid concentrations of individual plants exceeded toxicity thresholds on real world grasslands in Germany, but not on the population level. Alkaloid concentrations on five German grasslands with high alkaloid levels peaked in summer but were also below toxicity thresholds on population level. Furthermore, we showed that alkaloid concentrations follow the same seasonal trend, regardless of whether plant fresh or dry weight was used, in the field and in a common garden study. However, alkaloid concentrations were around three times higher when detected with dry weight. Finally, we showed that alkaloid concentrations can additionally be biased to different alkaloid detection methods. We highlight that toxicity risks should be analyzed using plant dry weight, but concentration trends of fresh weight are reliable. Full article
(This article belongs to the Special Issue Fungal Endophytes in Agriculture and Ecosystems)
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Open AccessArticle
Self-Inhibitory Activity of Trichoderma Soluble Metabolites and Their Antifungal Effects on Fusarium oxysporum
J. Fungi 2020, 6(3), 176; https://doi.org/10.3390/jof6030176 - 17 Sep 2020
Viewed by 411
Abstract
Self-inhibitory processes are a common feature shared by different organisms. One of the main mechanisms involved in these interactions regarding microorganisms is the release of toxic diffusible substances into the environment. These metabolites can exert both antimicrobial effects against other organisms as well [...] Read more.
Self-inhibitory processes are a common feature shared by different organisms. One of the main mechanisms involved in these interactions regarding microorganisms is the release of toxic diffusible substances into the environment. These metabolites can exert both antimicrobial effects against other organisms as well as self-inhibitory ones. The in vitro evaluation of these effects against other organisms has been widely used to identify potential biocontrol agents against phytopathogenic microorganisms. In the present study, we performed membrane assays to compare the self-inhibitory effects of soluble metabolites produced by several Trichoderma isolates and their antifungal activity against a phytopathogenic strain of Fusarium oxysporum. The results demonstrated that Trichoderma spp. present a high self-inhibitory activity in vitro, being affected in both their growth rate and the macroscopic structure of their colonies. These effects were highly similar to those exerted against F. oxysporum in the same conditions, showing no significant differences in most cases. Consequently, membrane assays may not be very informative by themselves to assess putative biocontrol capabilities. Therefore, different methods, or a combination of antifungal and self-inhibitory experiments, could be a better approach to evaluate the potential biocontrol activity of microbial strains in order to pre-select them for further in vivo trials. Full article
(This article belongs to the Special Issue Fungal Endophytes in Agriculture and Ecosystems)
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Open AccessArticle
EFE-Mediated Ethylene Synthesis Is the Major Pathway in the Citrus Postharvest Pathogen Penicillium digitatum during Fruit Infection
J. Fungi 2020, 6(3), 175; https://doi.org/10.3390/jof6030175 - 17 Sep 2020
Viewed by 422
Abstract
Penicillium digitatum is the main fungal postharvest pathogen of citrus fruit under Mediterranean climate conditions. The role of ethylene in the P. digitatum–citrus fruit interaction is unclear and controversial. We analyzed the involvement of the 2-oxoglutarate-dependent ethylene-forming enzyme (EFE)-encoding gene (efeA [...] Read more.
Penicillium digitatum is the main fungal postharvest pathogen of citrus fruit under Mediterranean climate conditions. The role of ethylene in the P. digitatum–citrus fruit interaction is unclear and controversial. We analyzed the involvement of the 2-oxoglutarate-dependent ethylene-forming enzyme (EFE)-encoding gene (efeA) of P. digitatum on the pathogenicity of the fungus. The expression of P. digitatumefeA parallels ethylene production during growth on PDA medium, with maximum levels reached during sporulation. We generated ΔefeA knockout mutants in P. digitatum strain Pd1. These mutants showed no significant defect on mycelial growth or sporulation compared to the parental strain. However, the knockout mutants did not produce ethylene in vitro. Citrus pathogenicity assays showed no differences in virulence between the parental and ΔefeA knockout mutant strains, despite a lack of ethylene production by the knockout mutant throughout the infection process. This result suggests that ethylene plays no role in P. digitatum pathogenicity. Our results clearly show that EFE-mediated ethylene synthesis is the major ethylene synthesis pathway in the citrus postharvest pathogen P. digitatum during both in vitro growth on PDA medium and the infection process, and that this hormone is not necessary for establishing P. digitatum infection in citrus fruit. However, our results also indicate that ethylene produced by P. digitatum during sporulation on the fruit surface may influence the development of secondary fungal infections. Full article
(This article belongs to the Special Issue Plant Fungal Pathogenesis)
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Open AccessArticle
Molecular Phylogeny and Morphology of Amphisphaeria (= Lepteutypa) (Amphisphaeriaceae)
J. Fungi 2020, 6(3), 174; https://doi.org/10.3390/jof6030174 - 17 Sep 2020
Viewed by 494
Abstract
Amphisphaeriaceous taxa (fungi) are saprobes on decaying wood in terrestrial, mangrove, and freshwater habitats. The generic boundaries of the family have traditionally been based on morphology, and the delimitation of genera has always been challenging. Amphisphaeria species have clypeate ascomata and 1-septate ascospores [...] Read more.
Amphisphaeriaceous taxa (fungi) are saprobes on decaying wood in terrestrial, mangrove, and freshwater habitats. The generic boundaries of the family have traditionally been based on morphology, and the delimitation of genera has always been challenging. Amphisphaeria species have clypeate ascomata and 1-septate ascospores and a coelomycetous asexual morph. Lepteutypa is different from Amphisphaeria in having eutypoid stromata and more than 1-septate ascospores. These main characters have been used for segregation of Lepteutypa from Amphisphaeria for a long time. However, the above characters are overlapping among Amphisphaeria and Lepteutypa species. Therefore, here we synonymized Lepteutypa under Amphisphaeria based on holomorphic morphology and multigene phylogeny. Further, our cluster analysis reveals the relationship between seven morphological traits among Amphisphaeria/Lepteutypa species and suggests those morphologies are not specific to either genus. Three new species (i.e., Amphisphaeria camelliae, A. curvaticonidia, and A. micheliae) are introduced based on morphology and LSU-ITS-RPB2-TUB2 phylogenies. Furthermore, the monotypic genus Trochilispora, which had been accepted in Amphisphaeriaceae, is revisited and synonymized under Hymenopleella and placed in Sporocadaceae. Full article
(This article belongs to the Special Issue Fungal Biodiversity and Ecology)
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Open AccessReview
Host Immune Defense upon Fungal Infections with Mucorales: Pathogen-Immune Cell Interactions as Drivers of Inflammatory Responses
J. Fungi 2020, 6(3), 173; https://doi.org/10.3390/jof6030173 - 17 Sep 2020
Viewed by 551
Abstract
During the last few decades, mucormycosis has emerged as one of the most common fungal infections, following candidiasis and aspergillosis. The fungal order responsible for causing mucormycosis is the Mucorales. The main hallmarks of this infection include the invasion of blood vessels, infarction, [...] Read more.
During the last few decades, mucormycosis has emerged as one of the most common fungal infections, following candidiasis and aspergillosis. The fungal order responsible for causing mucormycosis is the Mucorales. The main hallmarks of this infection include the invasion of blood vessels, infarction, thrombosis, and tissue necrosis, which are exhibited at the latest stages of the infection. Therefore, the diagnosis is often delayed, and the rapid progression of the infection severely endangers the life of people suffering from diabetes mellitus, hematological malignancies, or organ transplantation. Given the fact that mortality rates for mucormycosis range from 40 to 80%, early diagnosis and novel therapeutic strategies are urgently needed to battle the infection. However, compared to other fungal infections, little is known about the host immune response against Mucorales and the influence of inflammatory processes on the resolution of the infection. Hence, in this review, we summarized our current understanding of the interplay among pro-inflammatory cytokines, chemokines, and the host-immune cells in response to mucoralean fungi, as well as their potential use for immunotherapies. Full article
(This article belongs to the Special Issue Host Response to Mould Pathogens)
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Open AccessArticle
MrHex1 is Required for Woronin Body Formation, Fungal Development and Virulence in Metarhizium robertsii
J. Fungi 2020, 6(3), 172; https://doi.org/10.3390/jof6030172 - 14 Sep 2020
Viewed by 380
Abstract
The Woronin body (WB) is a peroxisome-derived dense-core vesicle, a self-assembling hexagonal crystal of a single protein Hex1. This organelle is specific to the ascomycete fungi belonging to the Pezizomycotina subphylum by functioning in sealing septal pores in response to mycelium damage and [...] Read more.
The Woronin body (WB) is a peroxisome-derived dense-core vesicle, a self-assembling hexagonal crystal of a single protein Hex1. This organelle is specific to the ascomycete fungi belonging to the Pezizomycotina subphylum by functioning in sealing septal pores in response to mycelium damage and the control of cell heterogeneity. We retrieved all available Hex1-domain containing proteins of different fungi from the GenBank database and found considerable length variations among 460 obtained Hex1 proteins. However, a highly conserved Hex1 domain containing 75 amino acid residues with a specific S/A-R/S-L consensus motif for targeting peroxisome is present at the carboxy-terminus of each protein. A homologous Hex1 gene, named MrHex1, was deleted in the entomopathogenic fungus Metarhizium robertsii. It was found that MrHex1 was responsible for WB formation in M. robertsii and involved in sealing septal pores to maintain cell integrity and heterogeneity. Different assays indicated that, relative to the wild-type (WT) strain, ∆Mrhex1 demonstrated a growth defect on a solid medium and substantial reductions of conidiation, appressorium formation and topical infectivity against insect hosts. However, there was no obvious virulence difference between WT and mutants during injection of insects. We also found that ∆MrHex1 could tolerate different stress conditions like the WT and the gene-rescued mutant of M. robertsii, which is in contrast to the reports of the stress-response defects of the Hex1 null mutants of other fungal species. In addition to revealing the phenotypic/functional alterations of the Hex1 deletion mutants between different pathotype fungi, the results of this study may benefit the understanding of the evolution and WB-control of fungal entomopathogenicity. Full article
(This article belongs to the Special Issue Host-Pathogen Interactions: Insects vs Fungi)
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Open AccessArticle
Genome-Scale Metabolic Model of the Human Pathogen Candida albicans: A Promising Platform for Drug Target Prediction
J. Fungi 2020, 6(3), 171; https://doi.org/10.3390/jof6030171 - 11 Sep 2020
Viewed by 524
Abstract
Candida albicans is one of the most impactful fungal pathogens and the most common cause of invasive candidiasis, which is associated with very high mortality rates. With the rise in the frequency of multidrug-resistant clinical isolates, the identification of new drug targets and [...] Read more.
Candida albicans is one of the most impactful fungal pathogens and the most common cause of invasive candidiasis, which is associated with very high mortality rates. With the rise in the frequency of multidrug-resistant clinical isolates, the identification of new drug targets and new drugs is crucial in overcoming the increase in therapeutic failure. In this study, the first validated genome-scale metabolic model for Candida albicans, iRV781, is presented. The model consists of 1221 reactions, 926 metabolites, 781 genes, and four compartments. This model was reconstructed using the open-source software tool merlin 4.0.2. It is provided in the well-established systems biology markup language (SBML) format, thus, being usable in most metabolic engineering platforms, such as OptFlux or COBRA. The model was validated, proving accurate when predicting the capability of utilizing different carbon and nitrogen sources when compared to experimental data. Finally, this genome-scale metabolic reconstruction was tested as a platform for the identification of drug targets, through the comparison between known drug targets and the prediction of gene essentiality in conditions mimicking the human host. Altogether, this model provides a promising platform for global elucidation of the metabolic potential of C. albicans, possibly guiding the identification of new drug targets to tackle human candidiasis. Full article
(This article belongs to the Special Issue Systems Biology in Fungal Research)
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Open AccessArticle
Interplay between Fungal Infection and Bacterial Associates in the Wax Moth Galleria mellonella under Different Temperature Conditions
J. Fungi 2020, 6(3), 170; https://doi.org/10.3390/jof6030170 - 10 Sep 2020
Viewed by 419
Abstract
Various insect bacterial associates are involved in pathogeneses caused by entomopathogenic fungi. The outcome of infection (fungal growth or decomposition) may depend on environmental factors such as temperature. The aim of this study was to analyze the bacterial communities and immune response of [...] Read more.
Various insect bacterial associates are involved in pathogeneses caused by entomopathogenic fungi. The outcome of infection (fungal growth or decomposition) may depend on environmental factors such as temperature. The aim of this study was to analyze the bacterial communities and immune response of Galleria mellonella larvae injected with Cordyceps militaris and incubated at 15 °C and 25 °C. We examined changes in the bacterial CFUs, bacterial communities (Illumina MiSeq 16S rRNA gene sequencing) and expression of immune, apoptosis, ROS and stress-related genes (qPCR) in larval tissues in response to fungal infection at the mentioned temperatures. Increased survival of larvae after C. militaris injection was observed at 25 °C, although more frequent episodes of spontaneous bacteriosis were observed at this temperature compared to 15 °C. We revealed an increase in the abundance of enterococci and enterobacteria in the midgut and hemolymph in response to infection at 25 °C, which was not observed at 15 °C. Antifungal peptide genes showed the highest expression at 25 °C, while antibacterial peptides and inhibitor of apoptosis genes were strongly expressed at 15 °C. Cultivable bacteria significantly suppressed the growth of C. militaris. We suggest that fungi such as C. militaris may need low temperatures to avoid competition with host bacterial associates. Full article
(This article belongs to the Special Issue Host-Pathogen Interactions: Insects vs Fungi)
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Open AccessArticle
Characterization of Five New Monosporascus Species: Adaptation to Environmental Factors, Pathogenicity to Cucurbits and Sensitivity to Fungicides
J. Fungi 2020, 6(3), 169; https://doi.org/10.3390/jof6030169 - 10 Sep 2020
Viewed by 390
Abstract
In this study, five new recently described Monosporascus species, M. brasiliensis, M. caatinguensis, M. mossoroensis, M. nordestinus, and M. semiaridus, which were found on weeds collected from cucurbit cultivation fields in northeastern Brazil, are [...] Read more.
In this study, five new recently described Monosporascus species, M. brasiliensis, M. caatinguensis, M. mossoroensis, M. nordestinus, and M. semiaridus, which were found on weeds collected from cucurbit cultivation fields in northeastern Brazil, are characterized regarding mycelial growth at different pH levels and salinity (NaCl) concentrations, their pathogenicity to selected cucurbit species, and their sensitivity to fungicides with different modes of action. Our results reveal great variability among the representative isolates of each Monosporascus spp. All of them showed a wide range of tolerance to different pH levels, and NaCl significantly reduced their in vitro mycelial growth, although no concentration was able to inhibit them completely. In pathogenicity tests, all seedlings of cucurbits evaluated, melon, watermelon, cucumber, and pumpkin, were susceptible to the five Monosporascus spp. in greenhouse experiments using artificial inoculation of roots. Moreover, all Monosporascus spp. were highly susceptible to the fungicides fludioxonil and fluazinam. Our findings provide relevant information about the response of these new Monosporascus spp. to environmental factors, plant genotypes and fungicides. Full article
(This article belongs to the Special Issue Plant Fungal Pathogenesis)
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Open AccessArticle
Interactive Impact of Arbuscular Mycorrhizal Fungi and Elevated CO2 on Growth and Functional Food Value of Thymus vulgare
J. Fungi 2020, 6(3), 168; https://doi.org/10.3390/jof6030168 - 09 Sep 2020
Viewed by 371
Abstract
Arbuscular mycorrhizal fungi (AMF) and elevated CO2 (eCO2) have been effectively integrated to the agricultural procedures as an ecofriendly approach to support the production and quality of plants. However, less attention has been given to the synchronous application of AMF [...] Read more.
Arbuscular mycorrhizal fungi (AMF) and elevated CO2 (eCO2) have been effectively integrated to the agricultural procedures as an ecofriendly approach to support the production and quality of plants. However, less attention has been given to the synchronous application of AMF and eCO2 and how that could affect the global plant metabolism. This study was conducted to investigate the effects of AMF and eCO2, individually or in combination, on growth, photosynthesis, metabolism and the functional food value of Thymus vulgare. Results revealed that both AMF and eCO2 treatments improved the photosynthesis and biomass production, however much more positive impact was obtained by their synchronous application. Moreover, the levels of the majority of the detected sugars, organic acids, amino acids, unsaturated fatty acids, volatile compounds, phenolic acids and flavonoids were further improved as a result of the synergistic action of AMF and eCO2, as compared to the individual treatments. Overall, this study clearly shows that co-application of AMF and eCO2 induces a synergistic biofertilization impact and enhances the functional food value of T. vulgare by affecting its global metabolism. Full article
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Open AccessReview
Phytophthora palmivora–Cocoa Interaction
J. Fungi 2020, 6(3), 167; https://doi.org/10.3390/jof6030167 - 09 Sep 2020
Viewed by 367
Abstract
Phytophthora palmivora (Butler) is an hemibiotrophic oomycete capable of infecting over 200 plant species including one of the most economically important crops, Theobroma cacao L. commonly known as cocoa. It infects many parts of the cocoa plant including the pods, causing black pod [...] Read more.
Phytophthora palmivora (Butler) is an hemibiotrophic oomycete capable of infecting over 200 plant species including one of the most economically important crops, Theobroma cacao L. commonly known as cocoa. It infects many parts of the cocoa plant including the pods, causing black pod rot disease. This review will focus on P. palmivora’s ability to infect a plant host to cause disease. We highlight some current findings in other Phytophthora sp. plant model systems demonstrating how the germ tube, the appressorium and the haustorium enable the plant pathogen to penetrate a plant cell and how they contribute to the disease development in planta. This review explores the molecular exchange between the oomycete and the plant host, and the role of plant immunity during the development of such structures, to understand the infection of cocoa pods by P. palmivora isolates from Papua New Guinea. Full article
(This article belongs to the Special Issue Plant Fungal Pathogenesis)
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Open AccessArticle
Chemical Characterization, Antioxidant, Enzyme Inhibition and Antimutagenic Properties of Eight Mushroom Species: A Comparative Study
J. Fungi 2020, 6(3), 166; https://doi.org/10.3390/jof6030166 - 09 Sep 2020
Viewed by 364
Abstract
This study aimed to determine the chemical composition and biologic activities of eight mushroom species (Amanita crocea, Hemileccinum depilatum, Cyclocybe cylindracea, Lactarius deliciosus, Hygrocybe acutoconica, Neoboletus erythropus, Russula aurea and Russula sanguinea). The antioxidant, enzyme [...] Read more.
This study aimed to determine the chemical composition and biologic activities of eight mushroom species (Amanita crocea, Hemileccinum depilatum, Cyclocybe cylindracea, Lactarius deliciosus, Hygrocybe acutoconica, Neoboletus erythropus, Russula aurea and Russula sanguinea). The antioxidant, enzyme inhibitory and mutagenic/antimutagenic activities were evaluated to provide data on the biologic activities. With respect to the chemical composition, LC–MS/MS technique was used to determine individual phenolic compounds present in the extracts. Antioxidant properties were investigated by different chemical methods including radical quenching (DPPH and ABTS), reducing power (CUPRAC and FRAP), phosphomolybdenum and metal chelating. In the enzyme inhibitory assays, cholinesterases, tyrosinase, amylase and glucosidase were used. Mutagenic and antimutagenic properties were evaluated by the Ames assay. In general, the best antioxidant abilities were observed from H. depilatum and N. erythropus, which also showed highest level of phenolics. The best cholinesterase inhibition ability was found from C. cylindracea (1.02 mg GALAE/g for AChE; 0.99 mg GALAE/g for BChE). Tyrosinase inhibition ability varied from 48.83 to 54.18 mg KAE/g. The extracts exhibited no mutagenic effects and showed significant antimutagenic potential. H. acutoconica, in particular depicted excellent antimutagenicity with a ratio of 97% for TA100 and with a rate of 96% for TA98 strain against mutagens in the presence of metabolic activation system. Results presented in this study tend to show that the mushroom species could be exploited as potential sources of therapeutic bioactive agents, geared towards the management of oxidative stress, global health problems and cancer. Full article
(This article belongs to the Special Issue Mushrooms—Mycotherapy and Mycochemistry)
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Open AccessArticle
Heterogeneity of Clinical Presentations and Paraclinical Explorations to Diagnose Disseminated Histoplasmosis in Patients with Advanced HIV: 34 Years of Experience in French Guiana
J. Fungi 2020, 6(3), 165; https://doi.org/10.3390/jof6030165 - 08 Sep 2020
Viewed by 294
Abstract
We aimed to describe the ways patients with disseminated histoplasmosis—a multifaceted and often lethal disease—present themselves and are explored. A retrospective, observational, multicentric study spanned the period between 1 January 1981 and 1 October 2014. Principal component analysis was performed for the sampling [...] Read more.
We aimed to describe the ways patients with disseminated histoplasmosis—a multifaceted and often lethal disease—present themselves and are explored. A retrospective, observational, multicentric study spanned the period between 1 January 1981 and 1 October 2014. Principal component analysis was performed for the sampling sites and for the clinical signs and symptoms. The factor loadings of the principal components were selected for eigenvalues > 1. The most frequent signs and symptoms were an alteration of the WHO general performance status, fever, digestive tract, respiratory signs and symptoms and lymphadenopathies. The most common sites sampled were bone marrow, respiratory tract, blood, lymph node and liver biopsies, with significant variations in the number of sites from which samples were taken to try to identify the pathogen. The principal component analysis clinical signs and symptoms leading to the diagnosis showed four main lines of variation. The factor loadings of the four main components were compatible with four broad types of clinical presentations and four types of exploration strategies. Extracting simple algorithms was difficult, emphasizing the importance of clinical expertise when diagnosis depends on obtaining a sample where Histoplasma can be seen or grown. Histoplasma antigen detection tests will help simplifying the algorithms. Full article
Open AccessArticle
Disseminated Histoplasmosis in HIV-Infected Patients: A Description of 34 Years of Clinical and Therapeutic Practice
J. Fungi 2020, 6(3), 164; https://doi.org/10.3390/jof6030164 - 07 Sep 2020
Viewed by 388
Abstract
Disseminated histoplasmosis is the main AIDS-defining infection of French Guiana. We aim to describe our therapeutic experience for 349 patients with disseminated histoplasmosis between 1 January 1981 and 10 January 2014 in French Guiana. Survival, delays for treatment initiation, duration of induction therapy, [...] Read more.
Disseminated histoplasmosis is the main AIDS-defining infection of French Guiana. We aim to describe our therapeutic experience for 349 patients with disseminated histoplasmosis between 1 January 1981 and 10 January 2014 in French Guiana. Survival, delays for treatment initiation, duration of induction therapy, and associated initial treatments are described. The death rate was 14.9 per 100 person-years, with an early drop in survival. Among those who died, >1/3 died within a year of HIV diagnosis, and ¾ of all patients with histoplasmosis had been diagnosed for HIV within a year. As induction treatment, 29% received liposomal amphotericin B, 12.9% received deoxycholate amphotericin B, 54% received itraconazole alone, and 21.8% received liposomal amphotericin B and itraconazole. The median delay between symptoms-onset and hospitalization was 19.5 days (IQR = 5–105). Liposomal amphotericin B or itraconazole was initiated shortly after admission. Treatment initiation was often presumptive for liposomal amphotericin B (27%) and itraconazole (20%). The median duration of liposomal amphotericin B treatment was 7 days (IQR = 5–11 days). The present study shows that ¾ of the patients were profoundly immunocompromised and had been diagnosed for HIV within the past year. Antifungal treatment was often initiated presumptively on admission. Over time there was a significant gradual decline in early death. Full article
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Open AccessCase Report
Pan-Echinocandin-Resistant Candida glabrata Bloodstream Infection Complicating COVID-19: A Fatal Case Report
J. Fungi 2020, 6(3), 163; https://doi.org/10.3390/jof6030163 - 06 Sep 2020
Cited by 1 | Viewed by 849
Abstract
Coinfections with bacteria or fungi may be a frequent complication of COVID-19, but coinfections with Candida species in COVID-19 patients remain rare. We report the 53-day clinical course of a complicated type-2 diabetes patient diagnosed with COVID-19, who developed bloodstream infections initially due [...] Read more.
Coinfections with bacteria or fungi may be a frequent complication of COVID-19, but coinfections with Candida species in COVID-19 patients remain rare. We report the 53-day clinical course of a complicated type-2 diabetes patient diagnosed with COVID-19, who developed bloodstream infections initially due to methicillin-resistant Staphylococcus aureus, secondly due to multidrug-resistant Gram-negative bacteria, and lastly due to a possibly fatal Candida glabrata. The development of FKS-associated pan-echinocandin resistance in the C. glabrata isolated from the patient after 13 days of caspofungin treatment aggravated the situation. The patient died of septic shock shortly before the prospect of receiving potentially effective antifungal therapy. This case emphasizes the importance of early diagnosis and monitoring for antimicrobial drug-resistant coinfections to reduce their unfavorable outcomes in COVID-19 patients. Full article
(This article belongs to the Special Issue Fungal Infections Complicating COVID-19)
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Open AccessArticle
Microglial Response to Aspergillus flavus and Candida albicans: Implications in Endophthalmitis
J. Fungi 2020, 6(3), 162; https://doi.org/10.3390/jof6030162 - 05 Sep 2020
Viewed by 466
Abstract
Aspergillus flavus is the most common etiology of fungal endophthalmitis in India, while Candida albicans is the causative agent in the West. In this study, we determined the role of microglial cells in evoking an inflammatory response following an infection with A. flavus [...] Read more.
Aspergillus flavus is the most common etiology of fungal endophthalmitis in India, while Candida albicans is the causative agent in the West. In this study, we determined the role of microglial cells in evoking an inflammatory response following an infection with A. flavus and C. albicans strains isolated from patients with endophthalmitis. Microglia (CHME-3) cells were infected with A. flavus and C. albicans and the expression of Toll-Like Receptors (TLRs), cytokines and Matrix metalloproteinases (MMPs) were assessed at various time intervals. A. flavus infected cells induced higher expressions of TLR-1, -2, -5, -6, -7 and -9 and cytokines such as IL-1α, IL-6, IL-8, IL-10 and IL-17. In contrast, C. albicans infected microglia induced only TLR-2 along with the downregulation of IL-10 and IL-17. The expression of MMP-9 (Matrix metalloproteinase-9) was however upregulated in both A. flavus and C. albicans infected microglia. These results indicate that microglial cells have the ability to incite an innate response towards endophthalmitis causing fungal pathogens via TLRs and inflammatory mediators. Moreover, our study highlights the differential responses of microglia towards yeast vs. filamentous fungi. Full article
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Open AccessArticle
German-Wide Analysis of the Prevalence and the Propagation Factors of the Zoonotic Dermatophyte Trichophyton benhamiae
J. Fungi 2020, 6(3), 161; https://doi.org/10.3390/jof6030161 - 03 Sep 2020
Viewed by 396
Abstract
For about 10 years, a new variant of the pathogen Trichophyton (T.) benhamiae has appeared in Germany, characterized by a previously unobserved culture phenotype with a strong yellow reverse. A few studies suggest that this new variety is now the most [...] Read more.
For about 10 years, a new variant of the pathogen Trichophyton (T.) benhamiae has appeared in Germany, characterized by a previously unobserved culture phenotype with a strong yellow reverse. A few studies suggest that this new variety is now the most common zoophilic dermatophyte in Germany. The guinea pig is the main carrier. Exact prevalence measurements are not yet available. Thus, the aim of our ongoing study was to collect data on the frequency and geographic distribution of the pathogen and its phenotypes (white and yellow) in humans and guinea pigs throughout Germany. Our former studies have already shown that animals from large breeding farms are particularly heavily affected. In contrast to this, 21 small, private breedings were sampled and husbandry conditions recorded. This placed us in a position to identify propagation factors and to give recommendations for containment. For animals from private breedings, we detected T. benhamiae with a prevalence of 55.4%, which is a reduction of nearly 40% compared with animals from large breeding farms. As risk factors, we identified the type of husbandry and the contact to other breedings. Furthermore, certain animal races, like Rex guinea pigs and races with long hair in combination with curls were predestined for colonization with T. benhamiae due to their phenotypic coat characteristics. A prevalence for infections with T. benhamiae of 36.2% has been determined for symptomatic pet guinea pigs suspected of having dermatophytosis and is comparable to the study of Kraemer et al. showing a prevalence of 34.9% in 2009 in Germany. The prevalence in humans is stable with about 2–3% comparing the data of 2010–2013 and 2018 in Thuringia. The new type of T. benhamiae was by far the most frequent cause in all settings. Full article
(This article belongs to the Special Issue Epidemiology, Diagnosis of Fungal Infections)
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Open AccessArticle
Intranasal Vaccine Using P10 Peptide Complexed within Chitosan Polymeric Nanoparticles as Experimental Therapy for Paracoccidioidomycosis in Murine Model
J. Fungi 2020, 6(3), 160; https://doi.org/10.3390/jof6030160 - 02 Sep 2020
Viewed by 408
Abstract
Paracoccidioidomycosis (PCM) is a granulomatous fungal disease caused by the dimorphic fungal species of Paracoccidioides, which mainly affects the lungs. Modern strategies for the treatment and/or prevention of PCM are based on a Th1-type immune response, which is important for controlling the [...] Read more.
Paracoccidioidomycosis (PCM) is a granulomatous fungal disease caused by the dimorphic fungal species of Paracoccidioides, which mainly affects the lungs. Modern strategies for the treatment and/or prevention of PCM are based on a Th1-type immune response, which is important for controlling the disease. One of the most studied candidates for a vaccine is the P10 peptide, derived from the 43 kDa glycoprotein of Paracoccidioides brasiliensis. In order to improve its immune modulatory effect, the P10 peptide was associated with a chitosan-conjugated nanoparticle. The nanoparticles presented 220 nm medium size, poly dispersion index (PDI) below 0.5, zeta potential of +20 mV and encapsulation efficiency around 90%. The nanoparticles’ non-toxicity was verified by hemolytic test and cell viability using murine macrophages. The nanoparticles were stable and presented physicochemical characteristics desirable for biological applications, reducing the fungal load and the usual standard concentration of the peptide from 4 to 20 times. Full article
(This article belongs to the Special Issue Systemic and Emerging Mycoses)
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Open AccessArticle
Toxin Production by Stachybotrys chartarum Genotype S on Different Culture Media
J. Fungi 2020, 6(3), 159; https://doi.org/10.3390/jof6030159 - 02 Sep 2020
Viewed by 462
Abstract
Stachybotrys (S.) chartarum had been linked to severe health problems in humans and animals, which occur after exposure to the toxic secondary metabolites of this mold. S. chartarum had been isolated from different environmental sources, ranging from culinary herbs and improperly [...] Read more.
Stachybotrys (S.) chartarum had been linked to severe health problems in humans and animals, which occur after exposure to the toxic secondary metabolites of this mold. S. chartarum had been isolated from different environmental sources, ranging from culinary herbs and improperly stored fodder to damp building materials. To access the pathogenic potential of isolates, it is essential to analyze them under defined conditions that allow for the production of their toxic metabolites. All Stachybotrys species are assumed to produce the immunosuppressive phenylspirodrimanes, but the highly cytotoxic macrocyclic trichothecenes are exclusively generated by the genotype S of S. chartarum. In this study, we have analyzed four genotype S strains initially isolated from three different habitats. We grew them on five commonly used media (malt-extract-agar, glucose-yeast-peptone-agar, potato-dextrose-agar, cellulose-agar, Sabouraud-dextrose-agar) to identify conditions that promote mycotoxin production. Using LC-MS/MS, we have quantified stachybotrylactam and all S-type specific macrocyclic trichothecenes (satratoxin G, H, F, roridin E, L-2, verrucarin J). All five media supported a comparable fungal growth and sporulation at 25 °C in the dark. The highest concentrations of macrocyclic trichothecenes were detected on potato-dextrose-agar or cellulose-agar. Malt-extract-agar let to an intermediate and glucose-yeast-peptone-agar and Sabouraud-dextrose-agar to a poor mycotoxin production. These data demonstrate that the mycotoxin production clearly depends on the composition of the respective medium. Our findings provide a starting point for further studies in order to identify individual components that either support or repress the production of mycotoxins in S. chartarum. Full article
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Open AccessReview
Antagonistic Yeasts: A Promising Alternative to Chemical Fungicides for Controlling Postharvest Decay of Fruit
J. Fungi 2020, 6(3), 158; https://doi.org/10.3390/jof6030158 - 31 Aug 2020
Cited by 1 | Viewed by 416
Abstract
Fruit plays an important role in human diet. Whereas, fungal pathogens cause huge losses of fruit during storage and transportation, abuse of chemical fungicides leads to serious environmental pollution and endangers human health. Antagonistic yeasts (also known as biocontrol yeasts) are promising substitutes [...] Read more.
Fruit plays an important role in human diet. Whereas, fungal pathogens cause huge losses of fruit during storage and transportation, abuse of chemical fungicides leads to serious environmental pollution and endangers human health. Antagonistic yeasts (also known as biocontrol yeasts) are promising substitutes for chemical fungicides in the control of postharvest decay owing to their widespread distribution, antagonistic ability, environmentally friendly nature, and safety for humans. Over the past few decades, the biocontrol mechanisms of antagonistic yeasts have been extensively studied, such as nutrition and space competition, mycoparasitism, and induction of host resistance. Moreover, combination of antagonistic yeasts with other agents or treatments were developed to improve the biocontrol efficacy. Several antagonistic yeasts are used commercially. In this review, the application of antagonistic yeasts for postharvest decay control is summarized, including the antagonistic yeast species and sources, antagonistic mechanisms, commercial applications, and efficacy improvement. Issues requiring further study are also discussed. Full article
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Open AccessReview
Sporulation in Ashbya gossypii
J. Fungi 2020, 6(3), 157; https://doi.org/10.3390/jof6030157 - 29 Aug 2020
Viewed by 589
Abstract
Ashbya gossypii is a filamentous ascomycete belonging to the yeast family of Saccharomycetaceae. At the end of its growth phase Ashbya generates abundant amounts of riboflavin and spores that form within sporangia derived from fragmented cellular compartments of hyphae. The length of [...] Read more.
Ashbya gossypii is a filamentous ascomycete belonging to the yeast family of Saccharomycetaceae. At the end of its growth phase Ashbya generates abundant amounts of riboflavin and spores that form within sporangia derived from fragmented cellular compartments of hyphae. The length of spores differs within species of the genus. Needle-shaped Ashbya spores aggregate via terminal filaments. A. gossypii is a homothallic fungus which may possess a and α mating types. However, the solo-MATa type strain is self-fertile and sporulates abundantly apparently without the need of prior mating. The central components required for the regulation of sporulation, encoded by IME1, IME2, IME4, KAR4, are conserved with Saccharomyces cerevisiae. Nutrient depletion generates a strong positive signal for sporulation via the cAMP-PKA pathway and SOK2, which is also essential for sporulation. Strong inhibitors of sporulation besides mutations in the central regulatory genes are the addition of exogenous cAMP or the overexpression of the mating type gene MATα2. Sporulation has been dissected using gene-function analyses and global RNA-seq transcriptomics. This revealed a role of Msn2/4, another potential PKA-target, for spore wall formation and a key dual role of the protein A kinase Tpk2 at the onset of sporulation as well as for breaking the dormancy of spores to initiate germination. Recent work has provided an overview of ascus development, regulation of sporulation and spore maturation. This will be summarized in the current review with a focus on the central regulatory genes. Current research and open questions will also be discussed. Full article
(This article belongs to the Special Issue Formation and Function of Fungal Ascospores)
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Open AccessArticle
Effects of mrpigG on Development and Secondary Metabolism of Monascus ruber M7
J. Fungi 2020, 6(3), 156; https://doi.org/10.3390/jof6030156 - 29 Aug 2020
Viewed by 475
Abstract
Monascus pigments (MPs) have been used as food colorants for several centuries in Asian countries and are now used throughout the world via Asian catering. The MP biosynthetic pathway has been well-illustrated, but the functions of a few genes, including mrpigG, in [...] Read more.
Monascus pigments (MPs) have been used as food colorants for several centuries in Asian countries and are now used throughout the world via Asian catering. The MP biosynthetic pathway has been well-illustrated, but the functions of a few genes, including mrpigG, in the MP gene cluster are still unclear. In the current study, in order to investigate the function of mrpigG in M. ruber M7, gene deletion (ΔmrpigG), complementation (ΔmrpigG::mrpigG) and overexpression (M7::PtrpC-mrpigG) mutants were successfully obtained. The morphologies and biomasses, as well as the MP and citrinin production, of these mutants were analyzed. The results revealed that the disruption, complementation and overexpression of mrpigG showed no apparent defects in morphology, biomass or citrinin production (except MP production) in ΔmrpigG compared with M. ruber M7. Although the MP profiles of ΔmrpigG and M. ruber M7 were almost the same—with both having four yellow pigments, two orange pigments (OPs) and two red pigments (RPs)—their yields were decreased in ΔmrpigG to a certain extent. Particularly, the content of rubropunctatin (an OP) and its derivative rubropunctamine (an RP) in ΔmrpigG, both of which have a five-carbon side chain, accounted for 57.7%, and 22.3% of those in M. ruber M7. On the other hand, monascorubrin (an OP) and its derivative monascorubramine (an RP), both of which have a seven-carbon side chain, were increased by 1.15 and 2.55 times, respectively, in ΔmrpigG compared with M. ruber M7. These results suggest that the MrPigG protein may preferentially catalyze the biosynthesis of MPs with a five-carbon side chain. Full article
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