3 Genetics, Biosynthesis, and Regulation of Aflatoxins and other Aspergillus flavus Secondary Metabolites

2013 ◽  
pp. 59-74 ◽  
Author(s):  
Saori Amaike ◽  
Katharyn J. Affeldt ◽  
Nancy P. Keller
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Flavus

scholarly journals Vibrio gazogenes inhibits aflatoxin production through downregulation of aflatoxin biosynthetic genes in Aspergillus flavus

2022 ◽  
Author(s):  
Shyam L. Kandel ◽  
Rubaiya Jesmin ◽  
Brian M. Mack ◽  
Rajtilak Majumdar ◽  
Matthew K. Gilbert ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Secondary Metabolite ◽  
Aspergillus Flavus ◽  
Fungal Biomass ◽  
Expression Profiles ◽  
Health Hazard ◽  
Gene Clusters ◽  
Aflatoxin Contamination ◽  
Aflatoxin Biosynthesis ◽  
Control Samples

Aspergillus flavus is an opportunistic pathogen of oilseed crops such as maize, peanut, cottonseed, and tree nuts and produces carcinogenic secondary metabolites known as aflatoxins during seed colonization. Aflatoxin contamination not only reduces the value of the produce but also is a health hazard to humans and animals. Previously, we observed inhibition of A. flavus aflatoxin biosynthesis upon exposure to the marine bacterium, Vibrio gazogenes (Vg). In this study, we used RNA sequencing to examine the transcriptional profiles of A. flavus treated with both live and heat-inactivated dead Vg and control samples. Fungal biomass, total accumulated aflatoxins, and expression profiles of genes constituting secondary metabolite biosynthetic gene clusters were determined at 24, 30, and 40 h after treatment. Statistically significant reductions in total aflatoxins were detected in Vg-treated samples as compared to control samples at 40 h. But no statistical difference in fungal biomass was observed upon these treatments. The Vg treatments were most effective on aflatoxin biosynthesis as was reflected in significant downregulation of majority of the genes in the aflatoxin gene cluster including the aflatoxin pathway regulator gene, aflR. Along with aflatoxin genes, we also observed significant downregulation in some other secondary metabolite gene clusters including cyclopiazonic acid and aflavarin, suggesting that the treatment may inhibit other secondary metabolites as well. Finally, a weighted gene correlation network analysis identified an upregulation of ten genes that were most strongly associated with Vg-dependent aflatoxin inhibition and provide a novel start-point in understanding the mechanisms that result in this phenomenon.

scholarly journals Comparative Study of the Secondary Metabolites of Sponge-derived Aspergillus flavus

2017 ◽  
Vol 1 (2) ◽  
pp. 45-51
Author(s):  
Kamilia Tawfik ◽  
Mostafa Mesbah ◽  
Sherief Khalifa ◽  
Eric Schmidt ◽  
Diaa Youssef
Keyword(s):  
Secondary Metabolites ◽  
Comparative Study ◽  
Aspergillus Flavus

scholarly journals Secondary Metabolites and Bioactivity of Hyophila involuta (Hook) Jaeg.

2015 ◽  
Vol 7 (4) ◽  
pp. 456-459
Author(s):  
Amos M. MAKINDE ◽  
Eunice A. FAJUYIGBE ◽  
Musibau O. ISA
Keyword(s):  
Staphylococcus Aureus ◽  
Secondary Metabolites ◽  
Aspergillus Flavus ◽  
Cardiac Glycosides ◽  
Therapeutic Potential ◽  
Ethanolic Extract ◽  
Acetone Extract ◽  
Significant Activity ◽  
Phytochemical Screening ◽  
Ethanolic Extracts

The phytochemical screening of Hyophila involuta collected from the Biological Garden of the Obafemi Awolowo University, Ile-Ife, Nigeria, was carried out to investigate the presence or absence of some secondary metabolites and its antibiotic potentials, using different extracts (with acetone and ethanol) on selected organisms. The extracts obtained were screened for the presence of secondary metabolites like alkaloids, anthraquinones, cardiac glycosides, flavonoids, phlobatanins, saponins, steroids, tannins, triterpenes and xanthoproteins. Antimicrobial activity of the extracts was carried out on Escherichia coli, Staphylococcus aureus, Aspergillus flavus and Candida albicans. Only acetone extract tested positive for the presence of flavonoids, while alkaloids and cardiac glycosides were detected present in both the acetone and ethanolic extracts. Flavonoids were detected present only in the acetone extract. Saponins were detected present only in the ethanolic extract. The extracts (acetone and ethanolic) showed significant activity on Staphylococcus aureus and Aspergillus flavus. The results obtained from this study indicated that H. involuta has medicinally important compounds, having therapeutic potential from which effective antimicrobial medicine can be sourced.

Aspergillus flavus aswA , a gene homolog of Aspergillus nidulans oefC , regulates sclerotial development and biosynthesis of sclerotium-associated secondary metabolites

2017 ◽  
Vol 104 ◽  
pp. 29-37 ◽  
Author(s):  
Perng-Kuang Chang ◽  
Leslie L. Scharfenstein ◽  
Robert W. Li ◽  
Natalia Arroyo-Manzanares ◽  
Sarah De Saeger ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Nidulans ◽  
Aspergillus Flavus ◽  
Sclerotial Development

scholarly journals The bZIP Transcription Factor AflRsmA Regulates Aflatoxin B1 Biosynthesis, Oxidative Stress Response and Sclerotium Formation in Aspergillus flavus

Toxins ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 271
Author(s):  
Xiuna Wang ◽  
Wenjie Zha ◽  
Linlin Liang ◽  
Opemipo Esther Fasoyin ◽  
Lihan Wu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Transcription Factor ◽  
Stress Response ◽  
Secondary Metabolites ◽  
Secondary Metabolism ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Opportunistic Pathogen ◽  
Oxidative Stress Response ◽  
Bzip Transcription Factor

Fungal secondary metabolites play important roles not only in fungal ecology but also in humans living as beneficial medicine or harmful toxins. In filamentous fungi, bZIP-type transcription factors (TFs) are associated with the proteins involved in oxidative stress response and secondary metabolism. In this study, a connection between a bZIP TF and oxidative stress induction of secondary metabolism is uncovered in an opportunistic pathogen Aspergillus flavus, which produces carcinogenic and mutagenic aflatoxins. The bZIP transcription factor AflRsmA was identified by a homology research of A. flavus genome with the bZIP protein RsmA, involved in secondary metabolites production in Aspergillus nidulans. The AflrsmA deletion strain (ΔAflrsmA) displayed less sensitivity to the oxidative reagents tert-Butyl hydroperoxide (tBOOH) in comparison with wild type (WT) and AflrsmA overexpression strain (AflrsmAOE), while AflrsmAOE strain increased sensitivity to the oxidative reagents menadione sodium bisulfite (MSB) compared to WT and ΔAflrsmA strains. Without oxidative treatment, aflatoxin B1 (AFB1) production of ΔAflrsmA strains was consistent with that of WT, but AflrsmAOE strain produced more AFB1 than WT; tBOOH and MSB treatment decreased AFB1 production of ΔAflrsmA compared to WT. Besides, relative to WT, ΔAflrsmA strain decreased sclerotia, while AflrsmAOE strain increased sclerotia. The decrease of AFB1 by ΔAflrsmA but increase of AFB1 by AflrsmAOE was on corn. Our results suggest that AFB1 biosynthesis is regulated by AflRsmA by oxidative stress pathways and provide insights into a possible function of AflRsmA in mediating AFB1 biosynthesis response host defense in pathogen A. flavus.

scholarly journals Natural Occurence of Aflatoxins in Wheat from Central Transylvania

2011 ◽  
Vol 68 (2) ◽  
Author(s):  
Simona MAN ◽  
Maria TOFANA ◽  
Sevastiţa MUSTE ◽  
Adriana PAUCEAN ◽  
Anamaria BIROU (POP)
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Aspergillus Parasiticus ◽  
Economic Losses ◽  
Important Food ◽  
And Storage ◽  
Harmful Effects

Aflatoxins (AFs), the secondary metabolites produced by species of Aspergillus, specifically Aspergillus flavus and Aspergillus parasiticus, have harmful effects on humans, animals, and crops that result in illnesses and economic losses. Wheat that is susceptible to these fungi infections through its growth, harvest, transport, and storage, is the most important food in Romania. Therefore, this study sought to present mycotoxins in wheat samples grown in different regions of Transyvania, the results being obtained in the climate of the year 2009-2010. Wheat samples were collected from Turda and Targu Mures. It was analyzed the presence of aflatoxins B1, B2, G1, G2, using HPTLC in twenty samples of wheat. Percentage of samples found positive for aflatoxin B1, B2, G1, G2 was 10%, 5%, 0%, 0%. Although the percentage of aflatoxin found in wheat is low, these percentages should be considered, in terms of exposure every day to mycotoxins through consumption of cereals and cereal-based products.

scholarly journals TLC Profile and Activity Test of Secondary Metabolites Aspergillus flavus “In-Habiting” Queen Termite’s Nest Macrotermes gilvus on Enriched Media

2018 ◽  
Vol 5 (1) ◽  
pp. 31
Author(s):  
Yohannes Alen ◽  
Rezki Amelia ◽  
Akmal Djamaan
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Flavus ◽  
Profile Analysis ◽  
Micrococcus Luteus ◽  
Diffusion Method ◽  
Activity Assay ◽  
Test Fungus ◽  
Activity Test ◽  
The Media ◽  
Termite Nest

Antibiotic are secondary metabolites yielded by microbe especially fungus. Previous research succesfull screened four kinds of fungus that live in termites queen’s nest, one of them was Aspergillus flavus. Furthermore, Alen et al (2016g) states that this fungus last to produce metabolite compounds on SDA media which only exist in first and second  subculture extract, omit gradually for the next culture. It was presumed happen caused a different habitat to grow. So it is necessary to enrich the media with queen termite nest to get back the initial metabolites. The enrichment was done using four different media concentrations (0.25; 0,50; 0.75 and 1 grams of nest/mL media). The results show that enrichment of 1 gram of nest/mL media provides the most optimum fungus growht. The third subculture of Aspergillus flavus is cultured on enriched media which will become the fourth subculture, this fungus cultured until tenth subculture, do extraction and   fracination to each culture. Based on TLC profile analysis, the initial metabolite not yet formed until tenth subculture, but forms six new stain terpenoid compounds.  The result of  columns chromatography obtained 10 sub-faction. Activity test was done by diffusion method to 12  test bacteria and 3 test fungus. Spot 2,5,6 (Rf 0.84; 0,36; 0,26) inhibit the growth of Pseudomonas aeruginosa ATCC 27853, spot 3,4 (Rf 0.74; 0,52) inhibit the growth of Micrococcus luteus ATCC 10240. The use of enriched media affect formation of  secondary metabolites Aspergillus flavus.  Keyword : Secondary metabolites, Aspergillus flavus, Macrotermes gilvus Hagen., Enriched media, TLC Profiles, Activity Assay

scholarly journals An Updated Review on the Secondary Metabolites and Biological Activities of Aspergillus ruber and Aspergillus flavus and Exploring the Cytotoxic Potential of Their Isolated Compounds Using Virtual Screening

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Fadia S. Youssef ◽  
Abdel Nasser B. Singab
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Flavus ◽  
Topoisomerase Ii ◽  
High Resolution Mass Spectrometry ◽  
Antioxidant Activities ◽  
Biological Activities ◽  
2D Nmr ◽  
Aspergillus Species ◽  
Cytotoxic Potential ◽  
In Silico Studies

The secondary metabolites and biological activities of Aspergillus ruber and Aspergillus flavus were comprehensively reported. About 70 compounds were isolated from both species that belong to different classes using conventional and advanced chromatographic techniques and unambiguously elucidated employing one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) and high resolution mass spectrometry (HRMS). Some of them displayed promising antiviral, anti-inflammatory, and antioxidant activities. In silico studies were conducted on human cyclin-dependent kinase 2 (CDK-2), human DNA topoisomerase II (TOP-2), and matrix metalloprotinase 13 (MMP-13) in an effort to explore the cytotoxic potential of the diverse compounds obtained from both Aspergillus species. 1,6,8-Trihydroxy-4-benzoyloxy-3-methylanthraquinone (23) revealed the most firm fitting with the active pockets of CDK-2 and MMP-13; meanwhile, variecolorin H alkaloid (14) showed the highest fitting within TOP-2 with ∆G equals to −36.51 kcal/mole. Thus, fungal metabolites could offer new drug entities for combating cancer. Relevant data about both Aspergillus species up to August 2020 were gathered from various databases comprising Scifinder (https://scifinder.cas.org/scifinder/login) for secondary metabolite-related studies; meanwhile, for biology-related articles, data were collected from both PubMed (http://www.ncbi.nlm.nih.gov/pubmed/) and Web of Knowledge (http://www.webofknowledge.com) as well.

scholarly journals Biofilm Mode of Cultivation Leads to an Improvement of the Entomotoxic Patterns of Two Aspergillus Species

2020 ◽  
Vol 8 (5) ◽  
pp. 705
Author(s):  
Frédéric Francis ◽  
Florent Druart ◽  
José Diana Di Mavungu ◽  
Marthe De Boevre ◽  
Sarah De Saeger ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Secondary Metabolite ◽  
Aspergillus Flavus ◽  
Aspergillus Oryzae ◽  
Proteomic Analysis ◽  
Cyclopiazonic Acid ◽  
Aspergillus Species ◽  
Metabolite Profiles

Two fungi, i.e., Aspergillus flavus Link and Aspergillus oryzae (Ahlb.) E. Cohn, were cultivated according to two methodologies, namely submerged and biofilm cultures with the primary aim to use their secondary metabolites the supernatant CL50, and CL90 varied between 1.3% (v/v) to 12.7% (v/v) for incubation times from 24 to 72 h. While the A. flavus supernatant entomotoxicity was higher than this of A. oryzae, the biofilm culture application increased the efficiency of the former. Proteomic analysis of the supernatants revealed discrepancies among the two species and modes of cultivation. Furthermore, the secondary metabolite profiles of both Aspergillus cultures were verified. Aspergillic acid, beta-cyclopiazonic acid, cyclopiazonic acid, ferrineospergillin, flavacol, and spermadin A were most predominant. Generally, these secondary metabolites were present in higher concentrations in the supernatants of A. flavus and biofilm cultures. These molecular identifications correlated positively with entomotoxic activity. Noteworthy, the absence of carcinogenic aflatoxins was remarkable, and it will allow further valorization to produce A. flavus to develop potential biopesticides.

scholarly journals Aspergillus flavus Secondary Metabolites: More than Just Aflatoxins

Food Safety ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 7-32 ◽  
Author(s):  
Jeffrey W. Cary ◽  
Matthew K. Gilbert ◽  
Matthew D. Lebar ◽  
Rajtilak Majumdar ◽  
Ana M. Calvo
Keyword(s):  
Secondary Metabolites ◽  
Aspergillus Flavus
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