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1.
BMC Genomics ; 23(1): 5, 2022 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-34983375

RESUMO

BACKGROUND: Aspergillus flavus, one of the causative agents of human fungal keratitis, can be phagocytosed by human corneal epithelial (HCE) cells and the conidia containing phagosomes mature into phagolysosomes. But the immunological responses of human corneal epithelial cells interacting with A. flavus are not clear. In this study, we report the expression of immune response related genes of HCE cells exposed to A. flavus spores using targeted transcriptomics. METHODS: Human corneal epithelial cell line and primary cultures were grown in a six-well plate and used for coculture experiments. Internalization of the conidia was confirmed by immunofluorescence microscopy of the colocalized endosomal markers CD71 and LAMP1. Total RNA was isolated, and the quantity and quality of the isolated RNA were assessed using Qubit and Bioanalyzer. NanoString nCounter platform was used for the analysis of mRNA abundance using the Human Immunology panel. R-package and nSolver software were used for data analysis. KEGG and FunRich 3.1.3 tools were used to analyze the differentially expressed genes. RESULTS: Different morphotypes of conidia were observed after 6 h of coculture with human corneal epithelial cells and found to be internalized by epithelial cells. NanoString profiling showed more than 20 differentially expressed genes in immortalized human corneal epithelial cell line and more than ten differentially expressed genes in primary corneal epithelial cells. Distinct set of genes were altered in their expression in cell line and primary corneal epithelial cells. KEGG pathway analysis revealed that genes associated with TNF signaling, NF-KB signaling, and Th17 signaling were up-regulated, and genes associated with chemokine signaling and B cell receptor signaling were down regulated. FunRich pathway analysis showed that pathways such as CDC42 signaling, PI3K signaling, and Arf6 trafficking events were activated by the clinical isolates CI1123 and CI1698 in both type of cells. CONCLUSIONS: Combining the transcript analysis data from cell lines and primary cultures, we showed the up regulation of immune defense genes in A. flavus infected cells. At the same time, chemokine signaling and B cell signaling pathways are downregulated. The variability in the expression levels in the immortalized cell line and the primary cultures is likely due to the variable epigenetic reprogramming in the immortalized cells and primary cultures in the absence of any changes in the genome. It highlights the importance of using both cell types in host-pathogen interaction studies.


Assuntos
Aspergillus flavus , Células Epiteliais/imunologia , Regulação da Expressão Gênica/imunologia , Aspergillus flavus/genética , Linhagem Celular , Quimiocinas/imunologia , Córnea/citologia , Córnea/microbiologia , Células Epiteliais/microbiologia , Humanos , Imunidade , Transdução de Sinais , Esporos Fúngicos
2.
J Hazard Mater ; 424(Pt A): 127173, 2022 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-34597924

RESUMO

Mycotoxins threaten global food safety, public health and cause huge socioeconomic losses. Early detection is an effective preventive strategy, yet efficient biomarkers for early detection of aflatoxigenic Aspergillus species are lacking. Here, we proposed to use untargeted metabolomics and machine learning to mine biomarkers of aflatoxigenic Aspergillus species. We systematically delineated metabolic differences across 568 extensive field sampling A. flavus and performed biomarker analysis. Versicolorin B, 11-hydroxy-O-methylsterigmatocystin et.al metabolites shown a high correlation (from 0.71 to 0.95) with strains aflatoxin-producing capacity. Molecular networking analysis deciphered the connection of aflatoxins and biomarkers as well as potential emerging mycotoxins. We then developed a model using the biomarkers as variables to discern aflatoxigenic Aspergillus species with 97.8% accuracy. A validation dataset and metabolome from other 16 fungal isolates confirmed the robustness and specificity of these biomarkers. We further demonstrated the solution feasibility in agricultural products by early detection of biomarkers, which predicted aflatoxin contamination risk 35-47 days in advance. A developed operable decision rule by the XGBoost algorithm help regulators to intuitively assess the risk prioritization with 87.2% accuracy. Our research provides novel insights into global food safety risk assessment which will be crucial for early prevention and control of mycotoxins.


Assuntos
Aflatoxinas , Aspergillus flavus , Aspergillus/genética , Biomarcadores , Metabolômica
3.
Pestic Biochem Physiol ; 180: 105001, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34955184

RESUMO

The chitosan nanomatrix incorporated with Cymbopogon citratus essential oil (Ne-CcEO) possess enhanced efficacy against the food-borne molds and aflatoxin B1 production compared to free essential oil. The CcEO was encapsulated inside the chitosan nanomatrix with an average size 147.41 ± 16.18 nm and characterized by Scanning electron microscopy, Fourier transforms infrared spectroscopy, and X-ray diffraction assay. The encapsulation efficiency and loading capacity were ranged between (41.68-76.78%) and (5.3-8.80%). The biochemical and in-silico analysis results revealed the interference in functioning of membrane integrity, mitochondrial membrane potential, antioxidant defense, carbon source metabolism, methylglyoxal, and laeA gene in response to treatment of Ne-CcEO (0.5 µl/ml). In addition, Ne-CcEO significantly protects the deterioration of Pennisetum glaucum (L.) R. Br. seed samples by A. flavus, aflatoxin B1 contamination, and lipid peroxidation. The Ne-CcEO could be considered as promising antifungal additives for the control of food-borne molds and aflatoxin B1 contamination in the food system.


Assuntos
Quitosana , Cymbopogon , Óleos Voláteis , Aflatoxina B1 , Antifúngicos/farmacologia , Aspergillus flavus , Quitosana/farmacologia , Óleos Voláteis/farmacologia
4.
Food Chem ; 372: 131317, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34818738

RESUMO

Pectinases hydrolyze pectin and make up 25% of global food processing enzyme sales. In this study, we aimed to purify exo-polygalacturonase (Exo-PG) by using galacturonic acid conjugated magnetic nanoparticles (MNPs) and examined its application in juice purification. The submerged fermentation was carried out in the presence of apple pectin (1%) to promote production of exo-PG from Aspergillus flavus. Maximum exo-PG activity was observed after 4 days (30 °C and pH 5.0). A single protein band (66 kDa) of purified exo-PG was observed in SDS-PAGE. Purification of exo-PG enzyme was âˆ¼ 10 fold with a yield of 29%. The enzyme retained 98% activity in the presence of 15 % glycerol at 4 °C. The purified exo-PG using MNPs yielded a 10-12% increase in juice production as compare to without treated fruit juice. To the best of our knowledge, this is the first report of affinity purification of exo-PG enzyme, using engineered magnetic nanoparticles.


Assuntos
Nanopartículas de Magnetita , Poligalacturonase , Aspergillus flavus/genética , Ácidos Hexurônicos , Pectinas , Poligalacturonase/genética
5.
Food Chem ; 372: 131221, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34649029

RESUMO

The direct incorporation of essential oils (EOs) into real food system faces numerous challenges due to high volatility, intense aroma, and instability. This research aimed to enhance the stability and bio-efficacy of Pimenta dioica essential oil (PDEO) through encapsulation in chitosan (CN) nanoemulsion. The nanoemulsion (CN-PDEO) was fabricated through ionic-gelation technique. CN-PDEO exhibited high nanoencapsulation efficiency (85.84%) and loading capacity (8.26%) with the particle size ranging between 18.53 and 70.56 nm. Bio-efficacy assessment results showed that CN-PDEO presented more effective antifungal and antiaflatoxigenic activity against Aspergillus flavus (AF-LHP-VS8) at lower doses (1.6 and 1.0 µL/mL) than the pure PDEO (2.5 and 1.5 µL/mL, respectively, p < 0.05). Additionally, CN-PDEO preserved model food (maize) from aflatoxin B1and lipid peroxidation without altering their sensory properties during storage with high safety profile (p < 0.05). Overall results concluded that CN-PDEO can be recommended for shelf-life extension of stored maize and other food commodities.


Assuntos
Quitosana , Óleos Voláteis , Aflatoxina B1 , Antifúngicos , Aspergillus flavus , Zea mays
6.
Int J Food Microbiol ; 361: 109457, 2022 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-34742145

RESUMO

Senna (Cassia angustifolia Vahl.) is a medicinal crop with laxative properties, and it has significant demand in the global pharmaceutical market. Senna pods are highly susceptible to aflatoxin contamination, and the successful export of pods is hindered due to the regulatory limits of importing countries. The senna pod water activity (aw) from harvest to storage is the key factor determining AFB1 accumulation. The temperature conditions from field to warehouse also interact with pod aw, which influences fungal growth and AFB1 production. The determination of an ideal combination of aw and temperature led to the assessment of the critical control point for AFB1 synthesis in senna. Hence, this study aimed to evaluate the influence of aw (0.99, 0.96, 0.93, 0.90, and 0.87 aw) and temperature (20, 28, and 37 °C) on fungal growth, gene expression (aflR and aflS), and AFB1 production by A. flavus in senna agar medium. The fungus showed the longest lag time (7.7 days) at 20 °C with 0.87 aw. We observed that 0.96 aw (P < 0.01) was optimum for the diametric growth rate at 28 and 37 °C. However, the peak expression of regulatory genes (aflR and aflS) and the maximum AFB1 production were observed only at 28 °C (0.96 aw). The highest growth rate occurred at 37 °C, which did not favor the expression of genes and AFB1 production. However, at 28 °C, it positively correlated with gene expression and AFB1 production. The suppressed expression of regulatory genes and a trace amount of aflatoxin B1 were found at 20 °C with all the tested aw. In our experiments, the low aw (0.87 and 0.90 aw) suppressed the fungal growth, gene expression, and AFB1 production of A. flavus at all of the tested temperatures (20, 28, and 37 °C). The rapid drying of senna pods with a low water activity (≤0.87 aw) and storage at low temperature (20 °C) are ideal conditions to avoid AFB1 and ensure the quality of produce for export.


Assuntos
Aspergillus flavus , Senna (Planta) , Aflatoxina B1 , Aspergillus flavus/genética , Expressão Gênica , Temperatura , Água
7.
J Agric Food Chem ; 69(45): 13608-13617, 2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34747604

RESUMO

Aspergillus flavus is saprophytic soil fungus that contaminates seed crops with the carcinogenic secondary metabolite aflatoxin, posing a significant threat to humans and animals. Ferrous sulfate is a common iron supplement that is used to the treatment of iron-deficiency anemia. Here, we identified an unexpected inhibitory role of ferrous sulfate on A. flavus. With specific fluorescent dyes, we detected several conidial ferroptosis hallmarks in conidia under the treatment of 1 mM Fe2+, including nonapoptosis necrosis, iron-dependent, lipid peroxide accumulation, and ROS burst. However, unlike traditional ferroptosis in mammals, Fe2+ triggered conidial ferroptosis in A. flavus was regulated by NADPH oxidase (NOXs) activation instead of Fenton reaction. Transcriptomic and some other bioinformatics analyses showed that NoxA in A. flavus might be a potential target of Fe2+, and thus led to the occurrence of conidial ferroptosis. Furthermore, noxA deletion mutant was constructed, and both ROS generation and conidial ferroptosis in ΔnoxA was reduced when exposed to Fe2+. Taken together, our study revealed an exogenous Fe2+-triggered conidial ferroptosis pathway mediated by NoxA of A. flavus, which greatly contributes to the development of an alternative strategy to control this pathogen.


Assuntos
Aflatoxinas , Ferroptose , Animais , Aspergillus flavus/genética , Humanos , Ferro , NADPH Oxidases , Esporos Fúngicos
8.
J Agric Food Chem ; 69(40): 11971-11981, 2021 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-34591470

RESUMO

Biotin is an important enzyme cofactor that plays a key role in all three domains. The classical bifunctional enzyme BioDA in eukaryotes (such as Aspergillus flavus and Arabidopsis thaliana) is involved in the antepenultimate and penultimate steps of biotin biosynthesis. In this study, we identified a A. flavus bifunctional gene bioDA which could complement both Escherichia coli ΔEcbioD and ΔEcbioA mutants. Interestingly, the separated domain of AfBioD and AfBioA could, respectively, fuse with EcBioA and EcBioD well and work together. What is more, we found that BioDA was almost localized to the mitochondria in A. flavus, as shown by N-terminal red fluorescent protein tag fusion. Noteworthy, the subcellular localization of AfBioDA is never affected by common environmental stresses (such as hyperosmotic stress or oxidative stress). The knockout strategy demonstrated that the deletion of AfbioDA gene from the chromosome impaired the biotin de novo synthesis pathway in A. flavus. Importantly, this A. flavus mutant blocked biotin production and decreased its pathogenicity to infect peanuts. Based on the structural comparison, we found that two inhibitors (amiclenomycin and gemcitabine) could be candidates for antifungal drugs. Taken together, our findings identified the bifunctional AfbioDA gene and shed light on biotin biosynthesis in A. flavus.


Assuntos
Aflatoxinas , Arabidopsis , Arabidopsis/metabolismo , Aspergillus flavus/genética , Aspergillus flavus/metabolismo , Vias Biossintéticas , Biotina , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Virulência
9.
An Acad Bras Cienc ; 93(suppl 3): e20200997, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34550200

RESUMO

Aspergillus genus causes many diseases, and the species Aspergillus flavus is highly virulent. Treatment of aspergillosis involves azole derivatives such as voriconazole and polyenes such as amphotericin B. Due to an increase in fungal resistance, treatments are now less effective; the search for new compounds with promising antifungal activity has gained importance. The aims of this study were to evaluate the effects of the synthetic amide 2-chloro-N-phenylacetamide (A1Cl) against strains of Aspergillus flavus and to elucidate its mechanism of action. Thus, the minimum inhibitory concentration, minimum fungicidal concentration, conidial germination, associations with antifungal agents, cell wall activities, membrane activities and molecular docking were evaluated. A1Cl presented antifungal activity against Aspergillus flavus strains with a minimum inhibitory concentration of between 16 and 256 µg/mL and a minimum fungicidal concentration between 32 and 512 µg/mL. The minimum inhibitory concentration of A1Cl also inhibited conidial germination, but when associated with amphotericin B and voriconazole, it promoted antagonistic effects. Binding to ergosterol on the fungal plasma membrane is the likely mechanism of action, along with possible inhibition of DNA synthesis through the inhibition of thymidylate synthase. It is concluded that the amide 2-chloro-N-phenylacetamide has promising antifungal potential.


Assuntos
Antifúngicos , Aspergillus flavus , Antifúngicos/farmacologia , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Triazóis , Voriconazol/farmacologia
10.
Appl Microbiol Biotechnol ; 105(20): 7871-7888, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34550439

RESUMO

Chemical control of fungal spoilage of postharvest cereal grains is an important strategy for the management of grain storage. Here, the potential antifungal activity of 1-nonanol, a main component of cereal volatiles, against Aspergillus flavus was studied. The growth of A. flavus was completely inhibited by 0.11 and 0.20 µL/mL 1-nonanol at vapor and liquid contact phases, respectively. Metabolomic analysis identified 135 metabolites whose expression was significantly different between 1-nonanol-treated and untreated A. flavus. These metabolites were involved in the tricarboxylic acid cycle, amino acid biosynthesis, protein degradation and absorption, aminoacyl-tRNA biosynthesis, mineral absorption, and in interactions with ABC transporters. Biochemical validation confirmed the disruptive effect of 1-nonanol on A. flavus growth, as indicated by the leakage of intracellular electrolytes, decreased succinate dehydrogenase, mitochondrial dehydrogenase, and ATPase activity, and the accumulation of reactive oxygen species. We speculated that 1-nonanol could disrupt cell membrane integrity and mitochondrial function and might induce apoptosis of A. flavus mycelia. Simulated grain storage experiments showed that 1-nonanol vapor, at a concentration of 264 µL/L, completely inhibited A. flavus growth in wheat, corn, and paddy grain with an 18% moisture content. This study provides new insights into the antifungal mechanism of 1-nonanol against A. flavus, indicating that it has a promising potential as a bio-preservative to prevent fungal spoilage of postharvest grains. KEY POINTS: • 1-Nonanol showed higher antifungal activity against A. flavus. • The antifungal mechanisms of 1-nonanol against A. flavus were revealed. • 1-Nonanol could damage cell membrane integrity and mitochondrial function.


Assuntos
Antifúngicos , Aspergillus flavus , Antifúngicos/farmacologia , Álcoois Graxos , Metabolômica
11.
Appl Microbiol Biotechnol ; 105(18): 6871-6886, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34477940

RESUMO

Aspergillus flavus is a notorious saprophytic fungus that compromises the quantity and quality of postharvest grains and produces carcinogenic aflatoxins. The natural compound hexanal disrupts cell membrane synthesis and mitochondrial function and induces apoptosis in A. flavus; here, we investigated the molecular mechanisms underlying these effects. The minimum inhibition and fungicidal concentration (MIC and MFC) of hexanal against A. flavus spores were 3.2 and 9.6 µL/mL, respectively. Hexanal exposure resulted in abnormal spore morphology and early spore apoptosis. These changes were accompanied by increased reactive oxygen species production, reduced mitochondrial membrane potential, and DNA fragmentation. Transcriptomic analysis revealed that hexanal treatment greatly altered the metabolism of A. flavus spores, including membrane permeability, mitochondrial function, energy metabolism, DNA replication, oxidative stress, and autophagy. This study provides novel insights into the mechanism underlying the antifungal activity of hexanal, suggesting that hexanal can be used an anti-A. flavus agent for agricultural applications. KEY POINTS: • Hexanal exposure resulted in abnormal spore morphology. • The apoptotic characteristics of A. flavus were induced after hexanal treatment. • Hexanal could change the expression of key A. flavus growth-related genes.


Assuntos
Aflatoxinas , Aspergillus flavus , Aflatoxinas/metabolismo , Aldeídos , Antifúngicos/metabolismo , Antifúngicos/farmacologia , Apoptose , Mitocôndrias , Esporos Fúngicos/metabolismo
12.
Med Mycol J ; 62(3): 47-52, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34471034

RESUMO

Aflatoxin produced by Aspergillus flavus is known to be strongly related to liver injury (hepatocellular carcinoma) and immune system damage involving leukocytes. This toxin suppresses both the cell-mediated immune system and macrophage function, and decreases the production of complement and interferon molecules. PURPOSE: To evaluate the presence of aflatoxin in infectious lesions as well as how the toxin is taken up by leukocytes. METHOD: Pathological specimens from a patient who died from aspergillosis caused by aflatoxin-producing A. flavus were used. Anti-aflatoxin B1 antibody was reacted with paraffin-embedded lesion specimens from the heart, kidney, and thyroid gland of the patient and observed microscopically. RESULT: Positive reactions were detected in fungal elements and leukocytes (neutrophils and macrophages) in inflammatory lesions. CONCLUSION: Within the patient's body, A. flavus likely produced aflatoxin, which then was taken up by neutrophils and macrophages.These results suggest that leukocyte function and the immune mechanism are locally suppressed by aflatoxin.


Assuntos
Aflatoxinas , Aspergilose , Aflatoxina B1 , Aspergillus flavus , Fungos , Humanos
13.
Int J Food Microbiol ; 357: 109369, 2021 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-34474198

RESUMO

Aspergillus parasiticus is a pre-harvest and postharvest pathogen that is known to produce aflatoxin; however, it is less studied compared to A. flavus. Inappropriate storage conditions are a cause of food spoilage and growth of mycotoxigenic fungi especially in low moisture foods thus constituting hazards to health. Hence, this study investigated the behaviour of A. parasiticus on aflatoxin production in inoculated wheat flour as influenced by storage conditions using the response surface methodology. Twenty experimental runs consisting of independent variables (incubation temperature (A), time (B) and (C) moisture content) and responses (aflatoxin concentrations, i.e., AFB1, AFB2, AFG1, AFG2 and AFTOT) were developed. A central composite face-centered design was used with lower and upper limits: A (25-35 °C), B (7-15 days) and C (15-25%), while the non-inoculated wheat flour served as the negative control. Aflatoxin production was determined using High Performance Liquid Chromatography (HPLC) according to standard procedures. Numerical and graphical process variables were optimized, adequate models were predicted and optimal point prediction for aflatoxin concentration was determined. AFG1 concentrations ranged from 1.10 to 360.06 µg/g, AFG2 (0.91-446.94 µg/g), AFB2 (7.95-488.77 µg/g), AFB1 (17.21-20,666.6 µg/g) and AFTOT (15.91-21,851.09 µg/g). Aflatoxin concentration increased with increase in 'B' and 'A' but decreased with prolonged increase in 'B'. AFB1 concentrations in A. parasiticus inoculated wheat flour increased at prolonged 'B' and 'A' at constant moisture (12.09%). A reduced cubic model was significantly adequate to describe the relationship between process variables and responses (AFG1 and AFG2), cubic model (AFB1 and AFTOT) and a transformed square root cubic model for AFG2 concentrations (p ≤ 0.05). 'A' influenced AFG1 production more than 'C' while 'C' and 'A' had no significant effect on AFG2 production. Process variables 'AB' influenced AFB2 concentrations more than 'C' while 'A' had a more significant effect on the AFTOT production than 'B' (p ≤ 0.05). The predicted (R2) and adjusted coefficient of regression (adj R2) were in reasonable agreement. After optimal point prediction and validation, minimum aflatoxin concentration ≤ 0 µg/g could be achieved at the predicted conditions (A = 30.42 °C, B = 10.58 days and C = 14.49%) except in AFG2 (3.33 µg/g).


Assuntos
Aflatoxinas , Aflatoxina B1/análise , Aflatoxinas/análise , Aspergillus , Aspergillus flavus , Farinha , Triticum
14.
Int J Food Microbiol ; 357: 109368, 2021 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-34481126

RESUMO

In this study, the effect of in-package gas composition on growth and aflatoxin production of toxigenic Aspergillus flavus was investigated. For this purpose, semi-dried red pepper samples and potato dextrose agar media with different pH values (3.5, 5.6, 7.0 and 9.0) were inoculated with A. flavus and packaged under different gas atmospheres (air, 100% N2, 70% N2 + 30% CO2 and 100% CO2). The growth of the fungus was monitored during storage at 25 °C for 8 days and the aflatoxin levels produced were determined at the end of storage. The highest growth rate was observed in the medium at pH 9.0 and the highest toxin production was in the medium at pH 5.6. Slowdowns up to 55.6% and 28.0% in the growth of A. flavus in the culture medium and red pepper were observed when packaging under 100% N2 was employed. It was found that 70% N2 + 30% CO2 atmosphere was more effective than 100% N2 in inhibiting the growth of A. flavus in red peppers; however, the difference between the aflatoxin levels produced in the samples packaged under these gas compositions was not significant (p > 0.05). CO2 concentrations higher than 90% in the package were quite effective against A. flavus resulting in 60% and 99% reductions in the growth and aflatoxin production of the fungus in red pepper.


Assuntos
Aflatoxinas , Capsicum , Aflatoxina B1 , Aspergillus flavus , Meios de Cultura
16.
Curr Microbiol ; 78(10): 3674-3685, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34398304

RESUMO

Many agricultural products are susceptible to contamination by aflatoxin-producing species from Aspergillus section Flavi. The objectives of this study were to determine the occurrence of Aspergillus section Flavi in four agricultural products, such as pistachio, walnut, hazelnut, and dried fruits, collected from market and retail shops in various areas of Kerman County and obtain information on the relationships between isolation source and ability to produce sclerotia and potential for aflatoxin production. Aspergillus species were identified based on morphological characteristics as well as subsequent sequencing of the parts of the ß-tubulin and calmodulin genes. From 207 isolated strains, the following species were identified: A. flavus, A. tamarii A. nomius, A. parasiticus, A. arachidicola, A. caelatus, A. pseudotamarii, and A. leporis. To the best of our knowledge, this is the first report of A. pseudotamarii and A. arachidicola with the potential to produce aflatoxins from dried apricots and hazelnuts, respectively. Sclerotial type was significantly different between isolates from different isolation sources. From 192 tested isolates, 38% were aflatoxin producer from which 5% were scored as strong aflatoxin producers and 33% as average aflatoxin producers. A significant difference in the population of aflatoxin-producing strains across the isolation sources was observed which may reflect host adaptation and thereby different vulnerabilities to aflatoxin-producing species among the examined products.


Assuntos
Aflatoxinas , Micotoxinas , Aspergillus/genética , Aspergillus flavus
17.
Colloids Surf B Biointerfaces ; 207: 111997, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34311197

RESUMO

Exploring new anti-aflatoxigenic materials and their mechanisms are critical to reduce the prevalence of drug-resistant fungi and the contamination of aflatoxins. Zinc oxide nanoparticles (ZnONPs) are promising antifungal candidates but supporting substrates generally affect their antifungal activities. In this study, ZnONPs with a three-dimensional flower-like hierarchical microstructure bound to different substrates as anti-aflatoxigenic composites were prepared using a facile deposition method. It was found that ZnO nanocomposites showed the substrate-dependent anti-aflatoxigenic activities. The antifungal activities of ZnO films toward A. flavus growth and aflatoxin B1 production decreased significantly in the order ZnO@Zn>ZnO@Sn>ZnO@Steel>ZnO@Glass. The electrical conductivity of the substrate should play an important role for antifungal response. When compared with ZnO@Sn and ZnO@Steel, the conductivity value of ZnO@Zn was 2.07-fold and 14.84-fold of them, respectively. The higher the electrical conductivity of the substrate, the better the anti-aflatoxigenic efficiency of the composite. Such anti-aflatoxigenic activity was also due to ROS generation through electron transfer between fungi and the ZnO-substrate system, which could provoke the strength of intracellular oxidative stress. This mechanism was further confirmed using several assays such as hyphal morphology analysis, Zn2+ release, ROS evaluation, lipid peroxidation and antioxidant response. Collectively, improvement in knowledge regarding anti-aflatoxigenic performance of ZnONPs can help develop novel and effective strategies to reduce fungi growth and aflatoxin contamination in the food field.


Assuntos
Preparações Farmacêuticas , Óxido de Zinco , Aspergillus flavus , Elétrons , Estresse Oxidativo , Óxido de Zinco/farmacologia
18.
Fungal Biol ; 125(8): 621-629, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34281655

RESUMO

Aspergillus flavus is a major fungal pathogen of plants and an opportunistic pathogen of humans. In addition to the direct impact of infection, it produces immunosuppressive and carcinogenic aflatoxins. The early detection of A. flavus is therefore necessary to diagnose and monitor fungal infection, to prevent aflatoxin contamination of food and feed, and for effective antifungal therapy. Aspergillus-specific monoclonal antibodies (mAbs) are promising as diagnostic and therapeutic reagents for the tracking and treatment of Aspergillus infections, respectively. However, A. flavus has a complex cell wall composition and dynamic morphology, hindering the discovery of mAbs with well-characterized targets. Here we describe the generation and detailed characterization of mAb5.52 (IgG2aκ) and mAb17.15 (IgG1κ), which bind specifically to the highly immunogenic cell wall antigen A. flavus mannoprotein 1 (Aflmp1). Both mAbs were generated using hybridoma technology following the immunization of mice with a recombinant truncated version of Aflmp1 (ExD, including the homologous CR4 domain) produced in bacteria. We show that mAb5.52 and mAb17.15 bind specifically to A. flavus and A. parasiticus cell wall fragments (CWFs), with no cross-reaction to CWFs from other fungal pathogens. Immunofluorescence microscopy revealed that both mAbs bind to the surface of Aspergillus hyphae and that mAb17.15 also binds to spores. The epitope for both mAbs is localized within the CR4 region of the Aflmp1 protein. These Aspergillus-specific mAbs may be useful for the early detection of fungal infection in food/feed crops, for serodiagnosis in patients with invasive aspergillosis caused by A. flavus infection and for the development of antibody-expressing disease-resistant crops.


Assuntos
Anticorpos Monoclonais , Aspergillus flavus , Animais , Anticorpos Monoclonais/metabolismo , Aspergilose/diagnóstico , Aspergilose/microbiologia , Aspergillus flavus/química , Parede Celular/química , Produtos Agrícolas/microbiologia , Proteínas Fúngicas/metabolismo , Hibridomas , Camundongos , Proteínas Recombinantes/imunologia
19.
Mol Genet Genomics ; 296(5): 1121-1134, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34181071

RESUMO

Codon usage bias influences the genetic features prevalent in genomes of all the organisms. It also plays a crucial role in establishing the host-pathogen relationship. The present study elucidates the role of codon usage pattern regarding the predilection of fungal pathogens Aspergillus flavus, Aspergillus niger, Fusarium oxysporum and Colletotrichum gloeosporioides towards host plant Zingiber officinale. We found a similar trend of codon usage pattern operative in plant and fungal pathogens. This concurrence might be attributed for the colonization of fungal pathogens in Z. officinale. The transcriptome of both plant and pathogens showed bias towards GC-ending codons. Natural selection and mutational pressure seem to be accountable for shaping the codon usage pattern of host and pathogen. We also identified some distinctive preferred codons in A. flavus, F. oxysporum and Z. officinale that could be regarded as signature codons for the identification of these organisms. Knowledge of favored, avoided and unique codons will help to devise strategies for reducing spice losses due to fungal pathogens.


Assuntos
Uso do Códon , Gengibre/genética , Gengibre/microbiologia , Interações Hospedeiro-Patógeno/genética , Aminoácidos/análise , Aspergillus flavus/genética , Aspergillus flavus/patogenicidade , Aspergillus niger/genética , Aspergillus niger/patogenicidade , Colletotrichum/genética , Colletotrichum/patogenicidade , Fusarium/genética , Fusarium/patogenicidade , Mutação , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Seleção Genética
20.
Arch Microbiol ; 203(7): 4485-4492, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34143269

RESUMO

Aflatoxin B1 is a carcinogenic mycotoxin that frequently contaminates crops worldwide. Current research indicates that the use of natural extracts to combat mycotoxin contamination may represent an eco-friendly, sustainable strategy to ensure food safety. Although Cannabis sativa L. has long been known for its psychoactive cannabinoids, it is also rich in many other bioactive molecules. This study examines extracts from various organs of Cannabis sativa L. to determine their ability to limit aflatoxin production and growth of Aspergillus flavus. The results indicate that flower extract is most effective for limiting the synthesis of aflatoxin B1, leading to an almost-complete inhibition of toxin production at a concentration of 0.225 mg dry matter per gram of culture medium. Since flower extract is rich in phenolic compounds, its total antioxidant ability and radical-scavenging capacity are determined. Compared with other anti-aflatoxigenic extracts, the anti-oxidative potential of Cannabis sativa L. flower extract appears moderate, suggesting that its anti-mycotoxin effect may be related to other bioactive compounds.


Assuntos
Aflatoxinas , Cannabis , Antifúngicos/química , Antifúngicos/farmacologia , Antioxidantes/farmacologia , Aspergillus flavus , Cannabis/química , Fenóis/química
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