Project description:<i>Aspergillus flavus</i> is a common contaminant in grain, oil and their products. Its metabolite aflatoxin B<sub>1</sub> (AFB<sub>1</sub>) has been proved to be highly carcinogenic. Therefore, it is of great importance to find possible antifungal substances to inhibit the growth and toxin production of <i>Aspergillus flavus</i>. Carvacrol (CV) was reported as a potent antifungal monoterpene derived from plants. In this paper, the antifungal effects and mechanism of CV on <i>Aspergillus flavus</i> were investigated. CV was shown good inhibition on the growth of <i>Aspergillus flavus</i> and the production of AFB<sub>1</sub>. CV used in concentrations ranging from 0, 50, 100 and 200 μg/mL inhibited the germination of spores, mycelia growth and AFB<sub>1</sub> production dose-dependently. To explore the antifungal mechanism of CV on <i>Aspergillus flavus</i>, we also detected the ergosterol content of <i>Aspergillus flavus</i> mycelia, employed Scanning Electron Microscopy (SEM) to observe mycelia morphology and utilized Ultra-High-Performance Liquid Chromatography-High-Resolution Mass Spectrometry (UHPLC-HRMS) to explore the lipidome profiles of <i>Aspergillus flavus</i>. The results showed that the production of ergosterol of mycelia was reduced as the CV treatment concentration increased. SEM photographs demonstrated a rough surface and a reduction in the thickness of hyphae in <i>Aspergillus flavus</i> treated with CV (200 µg/mL). In positive ion mode, 21 lipids of <i>Aspergillus flavus</i> mycelium were downregulated, and 11 lipids were upregulated after treatment with 200-µg/mL CV. In negative ion mode, nine lipids of <i>Aspergillus flavus</i> mycelium were downregulated, and seven lipids upregulated after treatment with 200-µg/mL CV. In addition, the analysis of different lipid metabolic pathways between the control and 200-µg/mL CV-treated groups demonstrated that glycerophospholipid metabolism was the most enriched pathway related to CV treatment.
Project description:Afla-Guard<sup>®</sup> is a commercial non-toxigenic <i>Aspergillus flavus</i> strain used to decrease aflatoxin contamination level in field. Its mitochondrial genome was sequenced, showing that its length is 29,208 bp with typical configuration of <i>Aspergillus</i> mitochondrial genome. 17 SNPs and 27 INDELs were identified by comparing with previous <i>A. flavus</i> mitochondrial genome. Phylogenetic trees present that <i>A. flavus</i> of Afla-Guard<sup>®</sup> was clustered with the previous <i>A. flavus</i> mitochondrial genome.
Project description:The emergence of resistant <i>Aspergillus</i> spp. is increasing worldwide. Long-term susceptibility surveillance for clinically isolated <i>Aspergillus</i> spp. strains is warranted for understanding the dynamic change in susceptibility and monitoring the emergence of resistance. Additionally, neither clinical breakpoints (CBPs) nor epidemiological cutoff values (ECVs) for <i>Aspergillus</i> spp. in China have been established. In this study, we performed a 20-year antifungal susceptibility surveillance for 706 isolates of <i>Aspergillus</i> spp. in a clinical laboratory at Peking University First Hospital from 1999 to 2019; and <i>in vitro</i> antifungal susceptibility to triazoles, caspofungin, and amphotericin B was determined by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method. It was observed that <i>Aspergillus fumigatus</i> was the most common species, followed by <i>Aspergillus flavus</i> and <i>Aspergillus terreus</i>. Forty isolates (5.7%), including <i>A. fumigatus</i>, <i>A. flavus</i>, <i>A. terreus</i>, <i>Aspergillus niger</i>, and <i>Aspergillus nidulans</i>, were classified as non-wild type (non-WT). Importantly, multidrug resistance was observed among <i>A. flavus</i>, <i>A. terreus</i>, and <i>A. niger</i> isolates. <i>Cyp51A</i> mutations were characterized for 19 non-WT <i>A. fumigatus</i> isolates, and TR<sub>34</sub>/L98H/S297T/F495I was the most prevalent mutation during the 20-year surveillance period. The overall resistance trend of <i>A. fumigatus</i> increased over 20 years in China. Furthermore, based on ECV establishment principles, proposed ECVs for <i>A. fumigatus</i> and <i>A. flavus</i> were established using gathered minimum inhibitory concentration (MIC)/minimum effective concentration (MEC) data. Consequently, all the proposed ECVs were identical to the CLSI ECVs, with the exception of itraconazole against <i>A. flavus</i>, resulting in a decrease in the non-WT rate from 6.0 to 0.6%.
Project description:Despite a high burden of chronic pulmonary aspergillosis (CPA) in Pakistan, <i>Aspergillus</i>-specific IgG testing is currently not available. Establishing cut-offs for <i>Aspergillus</i>-specific IgG for CPA diagnosis is crucial due to geographical variation. In settings such as Pakistan, where non-<i>Aspergillus fumigatus</i> (mainly <i>A. flavus</i>) <i>Aspergillus</i> species account for the majority of CPA cases, there is a need to explore additional benefit of <i>Aspergillus flavus</i>-specific IgG detection along with <i>A. fumigatus</i>-specific IgG detection. This study was conducted at the Aga Khan University, Karachi, Pakistan after ethical approval. Serum for IgG detection were collected after informed consent from healthy controls (<i>n</i> = 21), diseased controls (patients with lung diseases, <i>n</i> = 18), and CPA patients (<i>n</i> = 21). <i>A. fumigatus</i> and <i>A. flavus</i> IgG were detected using Siemens immulite assay. The sensitivity and specificity of <i>A. fumigatus</i>-specific IgG were 80.95% and 82.05%, respectively at a cut-off of 20 mg/L. The sensitivity and specificity of <i>A. flavus</i>-specific IgG were 80.95% and 79.49% at a cut-off of 30 mg/L. We report, for the first time, performance of <i>A. flavus</i>-specific IgG for CPA diagnosis. Although there was no statistically significant difference between the performance of both antigens, it seems contextually relevant to include <i>A. flavus</i> IgG in the CPA diagnostic algorithm in regions with higher non-<i>A. fumigatus</i> CPA infections.
Project description:RNA-seq was used to compare differential gene expressions for Aspergillus flavus wild type strain and ASPES transcription factor deletion strains.The goals of this study are to explore the aflatoxin regulation pathway in A. flavus. Overall design: Examination of differential gene expressions by RNA-seq in Aspergillus flavus wild type strain under both YES and YEP, and two APSES transcription factor mutant strains(AfRafA knoutout strain and AfStuA)
2018-12-25 | GSE107025 | GEO
Project description:Aspergillus flavus parental and progeny ddRADseq dataset
Project description:Aspergillus flavus is an important zoonotic pathogen and a well-known aflatoxin producer. Aspergillus flavus strains that are prevalent in Japanese environments are reported to be non-aflatoxigenic, although their aflatoxin productivity, especially among clinical isolates, has not been thoroughly investigated to date. In this study, we sequenced the genomes of ten strains of A. flavus isolated in Japan and compared their sequences with each other as well as with those of Aspergillus oryzae RIB40 and A. flavus NRRL3357. The phylogenetic analysis based on identified SNPs indicated that five strains were closer to A. oryzae RIB40 than to A. flavus NRRL3357. In contrast, of those isolates that were closer to A. flavus NRRL3357 than to A. oryzae RIB40, three were found to possess either the entire or partial aflatoxin biosynthesis gene cluster of NRRL3357-type. Furthermore, two of the three actually produced either aflatoxin B1 or an intermediate of the reaction leading to aflatoxin formation. Three of the ten strains we isolated were identified to possess part of the aflatoxin gene cluster, while five others retained the A. oryzae RIB40-type cluster. The genome data thus obtained may be further explored and utilized for comparative analysis of aflatoxin production in environmental and clinical isolates of A. flavus.
Project description:Although belong to the same genus, <i>Aspergillus fumigatus</i> is primarily involved in invasive pulmonary infection, whereas <i>Aspergillus flavus</i> is a common cause of superficial infection. In this study, we compared conidia (the infective propagules) of these two <i>Aspergillus</i> species. In immunocompetent mice, intranasal inoculation with conidia of <i>A. flavus</i> resulted in significantly higher inflammatory responses in the lungs compared to mice inoculated with <i>A. fumigatus</i> conidia. <i>In vitro</i> assays revealed that the dormant conidia of <i>A. flavus</i>, unlike <i>A. fumigatus</i> dormant conidia, are immunostimulatory. The conidial surface of <i>A. fumigatus</i> was covered by a rodlet-layer, while that of <i>A. flavus</i> were presented with exposed polysaccharides. <i>A. flavus</i> harbored significantly higher number of proteins in its conidial cell wall compared to <i>A. fumigatus</i> conidia. Notably, ?-1,3-glucan in the <i>A. flavus</i> conidial cell-wall showed significantly higher percentage of branching compared to that of <i>A. fumigatus</i>. The polysaccharides ensemble of <i>A. flavus</i> conidial cell wall stimulated the secretion of proinflammatory cytokines, and conidial cell wall associated proteins specifically stimulated IL-8 secretion from the host immune cells. Furthermore, the two species exhibited different sensitivities to antifungal drugs targeting cell wall polysaccharides, proposing the efficacy of species-specific treatment strategies. Overall, the species-specific organization of the conidial cell wall could be important in establishing infection by the two <i>Aspergillus</i> species.
Project description:BACKGROUND: Aspergillus flavus is intensively studied for its role in infecting crop plants and contaminating produce with aflatoxin, but its role as a human pathogen is less well understood. In parts of the Middle East and India, A. flavus surpasses A. fumigatus as a cause of invasive aspergillosis and is a significant cause of cutaneous, sinus, nasal and nail infections. METHODS: A collection of 45 clinical and 10 environmental A. flavus isolates from Iran were analysed using Variable-Number Tandem-Repeat (VNTR) markers with MICROSAT and goeBURST to determine their genetic diversity and their relatedness to clinical and environmental A. flavus isolates from Australia. Phylogeny was assessed using partial ?-tubulin and calmodulin gene sequencing, and mating type was determined by PCR. Antifungal susceptibility testing was performed on selected isolates using a reference microbroth dilution method. RESULTS: There was considerable diversity in the A. flavus collection, with no segregation on goeBURST networks according to source or geographic location. Three Iranian isolates, two from sinus infections and one from a paranasal infection grouped with Aspergillus minisclerotigenes, and all produced B and G aflatoxin. Phylogenic analysis using partial ?-tubulin and calmodulin sequencing confirmed two of these as A. minisclerotigenes, while the third could not be differentiated from A. flavus and related species within Aspergillus section flavi. Based on epidemiological cut-off values, the A. minisclerotigens and A. flavus isolates tested were susceptible to commonly used antifungal drugs. CONCLUSIONS: This is the first report of human infection due to A. minisclerotigenes, and it raises the possiblity that other species within Aspergillus section flavi may also cause clinical disease. Clinical isolates of A. flavus from Iran are not distinct from Australian isolates, indicating local environmental, climatic or host features, rather than fungal features, govern the high incidence of A. flavus infection in this region. The results of this study have important implications for biological control strategies that aim to reduce aflatoxin by the introduction of non-toxigenic strains, as potentially any strain of A. flavus, and closely related species like A. minisclerotigenes, might be capable of human infection.
Project description:The mitogenome of <i>Aspergillus flavus</i> SRRC1009 was sequenced to investigate intraspecific variations on mitochondrial genomes of <i>A. flavus</i>. It shows 29,202 bp with a typical configuration of <i>Aspergillus</i> mitogenome. Sixteen SNPs and 22 INDELs and 17 SNPs and 27 INDELs were identified against AflaGuard<sup>®</sup> and JQ355000, respectively. Phylogenetic trees present in the three <i>A. flavus</i> mitochondrial genomes were clustered with <i>A. oryzae</i> mitochondrial genome in one clade.