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Cells Sep 2022is a representative fungal species in the section Flavi and has been used as a model system to gain insights into fungal development and toxin production. has several... (Review)
Review
is a representative fungal species in the section Flavi and has been used as a model system to gain insights into fungal development and toxin production. has several adverse effects on humans, including the production of the most carcinogenic mycotoxin aflatoxins and causing aspergillosis in immune-compromised patients. In addition, infection of crops results in economic losses due to yield loss and aflatoxin contamination. is a saprophytic fungus that disperses in the ecosystem mainly by producing asexual spores (conidia), which also provide long-term survival in the harsh environmental conditions. Conidia are composed of the rodlet layer, cell wall, and melanin and are produced from an asexual specialized structure called the conidiophore. The production of conidiophores is tightly regulated by various regulators, including the central regulatory cascade composed of BrlA-AbaA-WetA, the fungi-specific velvet regulators, upstream regulators, and developmental repressors. In this review, we summarize the findings of a series of recent studies related to asexual development in and provide insights for a better understanding of other fungal species in the section Flavi.
Topics: Aflatoxins; Aspergillus flavus; Ecosystem; Fungal Proteins; Gene Expression Regulation, Fungal; Humans; Melanins; Spores, Fungal
PubMed: 36139369
DOI: 10.3390/cells11182796 -
Toxins Aug 2022Aflatoxin contamination poses serious health concerns to consumers of peanut and peanut products. This study aimed at investigating the response of peanuts to...
Aflatoxin contamination poses serious health concerns to consumers of peanut and peanut products. This study aimed at investigating the response of peanuts to Aspergillus flavus infection and aflatoxin accumulation. Isolates of A. flavus were characterised either as aflatoxigenic or non-aflatoxigenic using multiple cultural techniques. The selected isolates were used in an in vitro seed colonisation (IVSC) experiment on two A. flavus-resistant and susceptible peanut genotypes. Disease incidence, severity, and aflatoxin accumulation were measured. Genotypes differed significantly (p < 0.001) in terms of the incidence and severity of aflatoxigenic and non-aflatoxigenic A. flavus infection with the non-aflatoxigenic isolate having significantly higher incidence and severity values. There was no accumulation of aflatoxins in peanut genotypes inoculated with non-aflatoxigenic isolate, indicating its potential as a biocontrol agent. Inoculations with the aflatoxigenic isolate resulted in the accumulation of aflatoxin B1 and G1 in all the peanut genotypes. Aflatoxin B2 was not detected in ICGV−03401 (resistant genotype), while it was present and higher in Manipinta (susceptible genotype) than L027B (resistant genotype). ICGV−03401 can resist fungal infection and aflatoxin accumulation than L027B and Manipinta. Non-aflatoxigenic isolate detected in this study could further be investigated as a biocontrol agent.
Topics: Aflatoxin B1; Aflatoxins; Arachis; Aspergillus flavus; Genotype
PubMed: 36006198
DOI: 10.3390/toxins14080536 -
Toxins May 2021Aflatoxin B is a potent carcinogen produced by , mainly during grain storage. As pre-harvest methods are insufficient to avoid mycotoxin presence during storage, diverse...
Aflatoxin B is a potent carcinogen produced by , mainly during grain storage. As pre-harvest methods are insufficient to avoid mycotoxin presence during storage, diverse curative techniques are being investigated for the inhibition of fungal growth and aflatoxin detoxification. spp. represent an alternative as they are a promising source of detoxifying enzymes. Fifty-nine isolates and a strain from the commercial product Mycostop, evaluated against and ochratoxin A during previous work, were screened for their ability to inhibit growth and decrease the aflatoxin amount. The activities of bacterial cells and cell-free extracts (CFEs) from liquid cultures were also evaluated. Fifty-eight isolates were able to inhibit fungal growth during dual culture assays, with a maximal reduction going down to 13% of the control. Aflatoxin-specific production was decreased by all isolates to at least 54% of the control. CFEs were less effective in decreasing fungal growth (down to 40% and 55% for unheated and heated CFEs, respectively) and aflatoxin-specific production, with a few CFEs causing an overproduction of mycotoxins. Nearly all isolates were able to degrade AFB when growing in solid and liquid media. A total degradation of AFB was achieved by Mycostop on solid medium, as well as an almost complete degradation by IX20 in liquid medium (6% of the control). CFE maximal degradation went down to 37% of the control for isolate IX09. The search for degradation by-products indicated the presence of a few unknown molecules. The evaluation of residual toxicity of the tested isolates by the SOS chromotest indicated a detoxification of at least 68% of AFB's genotoxicity.
Topics: Aflatoxin B1; Aspergillus flavus; Carcinogens; Decontamination; Ochratoxins; Penicillium; Streptomyces
PubMed: 34066812
DOI: 10.3390/toxins13050340 -
G3 (Bethesda, Md.) Aug 2021Aspergillus flavus is an opportunistic pathogen of crops, including peanuts and maize, and is the second leading cause of aspergillosis in immunocompromised patients. A....
Aspergillus flavus is an opportunistic pathogen of crops, including peanuts and maize, and is the second leading cause of aspergillosis in immunocompromised patients. A. flavus is also a major producer of the mycotoxin, aflatoxin, a potent carcinogen, which results in significant crop losses annually. The A. flavus isolate NRRL 3357 was originally isolated from peanut and has been used as a model organism for understanding the regulation and production of secondary metabolites, such as aflatoxin. A draft genome of NRRL 3357 was previously constructed, enabling the development of molecular tools and for understanding population biology of this particular species. Here, we describe an updated, near complete, telomere-to-telomere assembly and re-annotation of the eight chromosomes of A. flavus NRRL 3357 genome, accomplished via long-read PacBio and Oxford Nanopore technologies combined with Illumina short-read sequencing. A total of 13,715 protein-coding genes were predicted. Using RNA-seq data, a significant improvement was achieved in predicted 5' and 3' untranslated regions, which were incorporated into the new gene models.
Topics: Aflatoxins; Aspergillus flavus; Chromosomes; Genome, Fungal; Humans; Sequence Analysis, DNA
PubMed: 34849826
DOI: 10.1093/g3journal/jkab213 -
Toxins Jun 2023Crop contamination by aflatoxin B1 (AFB1), an produced toxin, is frequently observed in tropical and subtropical regions. This phenomenon is emerging in Europe, most...
Crop contamination by aflatoxin B1 (AFB1), an produced toxin, is frequently observed in tropical and subtropical regions. This phenomenon is emerging in Europe, most likely as a result of climate change. Alternative methods, such as biocontrol agents (BCAs), are currently being developed to reduce the use of chemicals in the prevention of mycotoxin contamination. Actinobacteria are known to produce many bioactive compounds, and some of them can reduce in vitro AFB1 concentration. In this context, the present study aims to analyze the effect of a cell-free supernatant (CFS) from culture on the development of , as well as on its transcriptome profile using microarray assay and its impact on AFB1 concentration. Results demonstrated that in vitro, the CFS reduced the dry weight and conidiation of from 77% and 43%, respectively, and was therefore associated with a reduction in AFB1 concentration reduction to levels under the limit of quantification. The transcriptomic data analysis revealed that 5198 genes were differentially expressed in response to the CFS exposure and among them 5169 were downregulated including most of the genes involved in biosynthetic gene clusters. The aflatoxins' gene cluster was the most downregulated. Other gene clusters, such as the aspergillic acid, aspirochlorine, and ustiloxin B gene clusters, were also downregulated and associated with a variation in their concentration, confirmed by LC-HRMS.
Topics: Aspergillus flavus; Aflatoxin B1; Transcriptome; Aflatoxins
PubMed: 37505697
DOI: 10.3390/toxins15070428 -
Microbiology (Reading, England) Jun 2007Aspergillus infections have grown in importance in the last years. However, most of the studies have focused on Aspergillus fumigatus, the most prevalent species in the... (Review)
Review
Aspergillus infections have grown in importance in the last years. However, most of the studies have focused on Aspergillus fumigatus, the most prevalent species in the genus. In certain locales and hospitals, Aspergillus flavus is more common in air than A. fumigatus, for unclear reasons. After A. fumigatus, A. flavus is the second leading cause of invasive aspergillosis and it is the most common cause of superficial infection. Experimental invasive infections in mice show A. flavus to be 100-fold more virulent than A. fumigatus in terms of inoculum required. Particularly common clinical syndromes associated with A. flavus include chronic granulomatous sinusitis, keratitis, cutaneous aspergillosis, wound infections and osteomyelitis following trauma and inoculation. Outbreaks associated with A. flavus appear to be associated with single or closely related strains, in contrast to those associated with A. fumigatus. In addition, A. flavus produces aflatoxins, the most toxic and potent hepatocarcinogenic natural compounds ever characterized. Accurate species identification within Aspergillus flavus complex remains difficult due to overlapping morphological and biochemical characteristics, and much taxonomic and population genetics work is necessary to better understand the species and related species. The flavus complex currently includes 23 species or varieties, including two sexual species, Petromyces alliaceus and P. albertensis. The genome of the highly related Aspergillus oryzae is completed and available; that of A. flavus in the final stages of annotation. Our understanding of A. flavus lags far behind that of A. fumigatus. Studies of the genomics, taxonomy, population genetics, pathogenicity, allergenicity and antifungal susceptibility of A. flavus are all required.
Topics: Allergens; Animals; Antigens, Fungal; Aspergillosis; Aspergillus flavus; Humans; Mycotoxins
PubMed: 17526826
DOI: 10.1099/mic.0.2007/007641-0 -
Polish Journal of Microbiology Dec 2022Aflatoxin (AF)-producing fungi such as commonly contaminate animal feeds, causing high economic losses. is the most prevalent and produces AFB1, a potent mutagen, and...
Aflatoxin (AF)-producing fungi such as commonly contaminate animal feeds, causing high economic losses. is the most prevalent and produces AFB1, a potent mutagen, and carcinogen threatening human and animal health. is a large group of closely related fungi sharing number of morphological and genetic similarities that complicate the diagnosis of highly pathogenic strains. We used here morphological and molecular assays to characterize fungal isolates from animal feeds in Southwestern Algeria. These tools helped to identify 20 out of 30 strains, and 15 of them belonged to the section . Further analyses detected four out of 15 as belonging to group. PCR targeting the AF genes' intergenic region amplified a single 674 bp amplicon in all four isolates. The amplicons were digested with a II endonuclease, and three specific fragments were observed for but lacked two typical fragments. Sequencing data of four amplicons confirmed the presence of the two II restriction sites yielding the three fragments, confirming that all four strains were . In addition, this analysis illustrated the genetic variability within the strains.
Topics: Animals; Humans; Aspergillus flavus; Aspergillus; Aflatoxins; Polymerase Chain Reaction; Animal Feed
PubMed: 36537059
DOI: 10.33073/pjm-2022-048 -
Applied and Environmental Microbiology Mar 2019is an opportunistic fungal plant and human pathogen and a producer of mycotoxins, including aflatoxin B (AFB). As part of our ongoing studies to elucidate the...
is an opportunistic fungal plant and human pathogen and a producer of mycotoxins, including aflatoxin B (AFB). As part of our ongoing studies to elucidate the biological functions of the gene, we examined its role in the pathogenicity of both plant and animal model systems. encodes a putative RNA polymerase II (Pol II) transcription elongation factor previously characterized in , , and , where it was shown to regulate several important cellular processes, including morphogenesis and secondary metabolism. In addition, an initial study in indicated that also influences development and production of AFB; however, its effect on virulence is unknown. The current study reveals that the gene is indispensable for normal pathogenicity in plants when using peanut seed as an infection model, as well as in animals, as shown in the infection model. Interestingly, positively regulates several processes known to be necessary for successful fungal invasion and colonization of host tissue, such as adhesion to surfaces, protease and lipase activity, cell wall composition and integrity, and tolerance to oxidative stress. In addition, metabolomic analysis revealed that affects the production of several secondary metabolites, including AFB, aflatrem, leporins, aspirochlorine, ditryptophenaline, and aflavinines, supporting a role of as a global regulator of secondary metabolism. Heterologous complementation of an deletion strain with homologs from or fully rescued the wild-type phenotype, indicating that these homologs are functionally conserved among these three species. In this study, the epigenetic global regulator , which encodes a putative RNA-Pol II transcription elongation factor-like protein, was characterized in the mycotoxigenic and opportunistic pathogen Specifically, its involvement in pathogenesis in plant and animal models was studied. Here, we show that positively regulates virulence in both models. Furthermore, -dependent effects on factors necessary for successful invasion and colonization of host tissue by were also assessed. Our study indicates that plays a role in adherence to surfaces, hydrolytic activity, normal cell wall formation, and response to oxidative stress. This study also revealed a profound effect of on the metabolome of , including the production of potent mycotoxins.
Topics: Aflatoxin B1; Animals; Arachis; Aspergillus flavus; Fungal Proteins; Gene Expression Regulation, Fungal; Moths; Plant Diseases; Secondary Metabolism; Transcriptional Elongation Factors; Virulence
PubMed: 30635379
DOI: 10.1128/AEM.02446-18 -
Toxins Nov 2021poses a threat to society economy and public health due to aflatoxin production. is a gene located in the aflatoxin gene cluster, but the function of AflN is undefined...
poses a threat to society economy and public health due to aflatoxin production. is a gene located in the aflatoxin gene cluster, but the function of AflN is undefined in . In this study, is knocked out and overexpressed to study the function of AflN. The results indicated that the loss of AflN leads to the defect of aflatoxin biosynthesis. AflN is also found to play a role in conidiation but not hyphal growth and sclerotia development. Moreover, AlfN is related to the response to environmental oxidative stress and intracellular levels of reactive oxygen species. At last, AflN is involved in the pathogenicity of to host. These results suggested that AflN played important roles in aflatoxin biosynthesis, conidiation and reactive oxygen species generation in , which will be helpful for the understanding of function, and will be beneficial to the prevention and control of and aflatoxins contamination.
Topics: Aflatoxins; Aspergillus flavus; Fungal Proteins; Gene Expression Regulation, Fungal; Multigene Family; Oxidative Stress; Reactive Oxygen Species
PubMed: 34822615
DOI: 10.3390/toxins13110831 -
Toxins Dec 2009Cyclopiazonic acid (CPA) is an indole-tetramic acid neurotoxin produced by some of the same strains of A. flavus that produce aflatoxins and by some Aspergillus oryzae... (Review)
Review
Cyclopiazonic acid (CPA) is an indole-tetramic acid neurotoxin produced by some of the same strains of A. flavus that produce aflatoxins and by some Aspergillus oryzae strains. Despite its discovery 40 years ago, few reviews of its toxicity and biosynthesis have been reported. This review examines what is currently known about the toxicity of CPA to animals and humans, both by itself or in combination with other mycotoxins. The review also discusses CPA biosynthesis and the genetic diversity of CPA production in A. flavus/oryzae populations.
Topics: Aflatoxins; Aspergillus flavus; Aspergillus oryzae; Humans; Mycotoxins
PubMed: 22069533
DOI: 10.3390/toxins1020074