scholarly journals Corn Seed Proteins Inhibitory to Aspergillus flavus and Aflatoxin Biosynthesis

1997 ◽  
Vol 87 (6) ◽  
pp. 622-627 ◽  
Author(s):  
Zhengyu Huang ◽  
Donald G. White ◽  
Gary A. Payne
Keyword(s):  
Aspergillus Flavus ◽  
Seed Proteins ◽  
Fungal Growth ◽  
Growth Inhibitor ◽  
Water Soluble ◽  
Biologically Active ◽  
Proteinase K ◽  
Aflatoxin Biosynthesis ◽  
Biosynthesis Inhibitor ◽  
Aflatoxin Accumulation

This study reports the presence of two fractions from corn seeds inhibitory to aflatoxin formation. Using a sensitive laboratory assay that can measure both inhibition of fungal growth and inhibition of aflatoxin biosynthesis, we examined aqueous extracts from seeds of Tex6, a corn inbred shown to be highly resistant to aflatoxin accumulation in field and laboratory evaluations. In these extracts, we identified two biologically active fractions. One inhibited growth of Aspergillus flavus and, thus, aflatoxin accumulation, and the other inhibited aflatoxin formation with little effect on fungal growth. The compounds responsible for these activities appear to be proteaceous, as they are water soluble, heat labile, and sensitive to proteinase K treatment. The compounds were partially purified by ultrafiltration and chromatography. The estimated molecular mass of the growth inhibitor is approximately 28 kDa, and that of the aflatoxin biosynthesis inhibitor appears to be greater than 100 kDa. Partially purified preparations of the growth inhibitor and aflatoxin biosynthesis inhibitor cause 50% inhibition at 26 and 75 μg of protein/ml, respectively. The presence of these compounds in Tex6 may explain its resistance to aflatoxin accumulation.

An inhibitor of aflatoxin biosynthesis in developing cottonseed

1988 ◽  
Vol 66 (5) ◽  
pp. 998-1002 ◽  
Author(s):  
Susan P. McCormick ◽  
Deepak Bhatnagar ◽  
Wilton R. Goynes ◽  
Louise S. Lee
Keyword(s):  
Growth Inhibition ◽  
Molecular Mass ◽  
Aspergillus Flavus ◽  
Anion Exchanger ◽  
Inhibitory Activity ◽  
Fungal Growth ◽  
Aflatoxin Biosynthesis ◽  
Seed Moisture ◽  
Aflatoxin Accumulation ◽  
Fungal Growth Inhibition

A factor present in the coats of young developing cottonseed (20–25 days old) but absent from older developing seeds (35–40 days old) significantly inhibited (> 85%) aflatoxin formation by Aspergillus flavus without affecting fungal growth. Inhibition was independent of levels of seed moisture, phenolics, or tannins. The inhibitory factor was nondialyzable (molecular mass > 8 kDa); the inhibition of aflatoxin accumulation was dependent on its concentration. The inhibitor was probably an anionic protein since it bound to an anion exchanger and was eluted at 0.15 M salt. The inhibitor did not exhibit a peroxidase-like activity, even though it was observed that the factor was stable at temperatures below 70 °C and that sugar moieties were associated with the inhibitory property. The inhibitory activity was not similar to that of a serine protease.

Resistance to Aflatoxin Contamination in Corn as Influenced by Relative Humidity and Kernel Germination

1996 ◽  
Vol 59 (3) ◽  
pp. 276-281 ◽  
Author(s):  
B. Z. GUO ◽  
J. S. RUSSIN ◽  
R. L. BROWN ◽  
T. E. CLEVELAND ◽  
N. W. WIDSTROM
Keyword(s):  
Relative Humidity ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Resistance Mechanisms ◽  
Aflatoxin Contamination ◽  
Aflatoxin Biosynthesis ◽  
Aflatoxin Accumulation ◽  
Moisture Conditions ◽  
Very High ◽  
Fungus Growth

Kernels of corn population GT-MAS:gk, resistant to aflatoxin B1 production by Aspergillus flavus, and susceptible Pioneer hybrid 3154 were tested for aflatoxin when incubated under different relative humidities (RH). High aflatoxin levels were not detected in either genotype at RH < 91%. Resistance in GT-MAS:gk was consistent across all RH levels (91 to 100%) at which significant aflatoxin accumulation was detected. Aflatoxin levels in GT-MAS:gk averaged about 98% less than those in susceptible Pioneer 3154, which suggests that storage of this or other genotypes with similar resistance mechanisms may be possible under moisture conditions less exacting than are required with susceptible hybrids. Results for fungus growth and sporulation ratings on kernel surfaces were similar to those for aflatoxin levels. When kernels of both genotypes were preincubated 3 days at 100% RH prior to inoculation with A. flavus, germination percentages increased to very high levels compared to those of kernels that were not preincubated. In preincubated kernels aflatoxin levels remained consistently low in GT-MAS:gk but decreased markedly (61%) in Pioneer 3154. When eight susceptible hybrids were evaluated for aflatoxin accumulation in preincubated kernels, seven of these supported significantly lower toxin levels than kernels not subjected to preincubation. Average reduction across hybrids was 83%, and reductions within hybrids ranged from 68 to 96%. Preincubated kernels of one susceptible hybrid (Deltapine G-4666) supported aflatoxin levels comparable to those in resistant GT-MAS:gk. Data suggest that an inhibitor of aflatoxin biosynthesis may be induced during kernel germination. Possible mechanisms for embryo effects on resistance to aflatoxin accumulation are discussed.

scholarly journals Screening of Lemon Balm Extracts for Anti-Aflatoxigenic, Antioxidant and Other Biological Activities

2019 ◽  
Author(s):  
Efstathia Skotti ◽  
Nefeli Sophia Sotiropoulou ◽  
Iliada Lappa ◽  
Maria Kaiafa ◽  
Dimitrios Tsitsigiannis ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Aspergillus Flavus ◽  
Biological Activities ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Water Soluble ◽  
Phytochemical Analysis ◽  
Growth Enhancement ◽  
Mycelium Growth ◽  
Lemon Balm

Lemon balm extracts by dry plant material of Melissa officinalis were tested against their efficacy against for different fungal species Alternaria alternata, Fusarium oxysporum, Aspergillus flavus and Beauveria bassiana. The aqueous phase of the extract was evaluated for antioxidant, antifungal and also anti-aflatoxigenic activity. A synergism evaluation was also performed concerning, the small quantity of lemon balm polar essential oil compounds extracted into the infusion and the water soluble compounds in the extract. The experiments were conducted in solid cultures and the growth inhibition was demonstrated by measuring mycelial diameter. Additionally, the effect on conidia production was also demonstrated. Lemon balm was also used for in situ test on Pistachia vera seed against Aspergillus flavus growth and aflatoxin production. Results revealed enhancement of fungal growth by lemon balm extracts however total inhibition of aflatoxins production on Pistachia vera seeds was observed, and both actions were tried to attributed to volatile and water soluble compounds identified based on GC/MS, HPLC/DAD and LC/MS, and the observed antioxidant activity. Volatile and water - soluble compounds found to be in absolute synergism in mycelium growth enhancement and the observed anti-aflatoxigenic activity addressed to the high antioxidant activity observed and synergistic action between the other water soluble phenolic compounds identified in the extract. The findings of this study underline the high biological active potential of lemon balm extracts under various screening test since for the first time full phytochemical analysis of lemon balm extracts.

scholarly journals Transcriptomic Insights into Benzenamine Effects on the Development, Aflatoxin Biosynthesis, and Virulence of Aspergillus flavus

Toxins ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 70 ◽  
Author(s):  
Mingguan Yang ◽  
Laifeng Lu ◽  
Shuhua Li ◽  
Jing Zhang ◽  
Zhenjing Li ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Pathogenic Fungus ◽  
Underlying Mechanism ◽  
Aflatoxin Contamination ◽  
Mrna Levels ◽  
Aflatoxin Biosynthesis ◽  
Inhibitory Effects ◽  
Great Capacity ◽  
Aflatoxin Accumulation ◽  
New Strategies

Aspergillus flavus is a soilborne pathogenic fungus that poses a serious public health threat due to it contamination of food with carcinogenic aflatoxins. Our previous studies have demonstrated that benzenamine displayed strong inhibitory effects on the mycelial growth of A. flavus. In this study, we systematically investigated the inhibitory effects of benzenamine on the development, aflatoxin biosynthesis, and virulence in A. flavus, as well as the underlying mechanism. The results indicated that benzenamine exhibited great capacity to combat A. flavus at a concentration of 100 µL/L, leading to significantly decreased aflatoxin accumulation and colonization capacity in maize. The transcriptional profile revealed that 3589 genes show altered mRNA levels in the A. flavus after treatment with benzenamine, including 1890 down-regulated and 1699 up-regulated genes. Most of the differentially expressed genes participated in the biosynthesis and metabolism of amino acid, purine metabolism, and protein processing in endoplasmic reticulum. Additionally, the results brought us to a suggestion that benzenamine affects the development, aflatoxin biosynthesis, and pathogenicity of A. flavus via down-regulating related genes by depressing the expression of the global regulatory factor leaA. Overall, this study indicates that benzenamine have tremendous potential to act as a fumigant against pathogenic A. flavus. Furthermore, this work offers valuable information regarding the underlying antifungal mechanism of benzenamine against A. flavus at the level of transcription, and these potential targets may be conducive in developing new strategies for preventing aflatoxin contamination.

Construction and Preliminary Evaluation of an Aspergillus flavus Reporter Gene Construct as a Potential Tool for Screening Aflatoxin Resistance

2003 ◽  
Vol 66 (10) ◽  
pp. 1927-1931 ◽  
Author(s):  
ROBERT L. BROWN ◽  
CARMEN S. BROWN-JENCO ◽  
DEEPAK BHATNAGAR ◽  
GARY A. PAYNE
Keyword(s):  
Reporter Gene ◽  
Aspergillus Flavus ◽  
Fungal Growth ◽  
Gus Expression ◽  
Alternative Methods ◽  
Preliminary Evaluation ◽  
Gene Construct ◽  
Reporter Gene Construct ◽  
Aflatoxin Accumulation ◽  
Maize Kernels

Effective preharvest strategies to eliminate aflatoxin accumulation in crops are not presently available. The molecular biology of aflatoxin biosynthesis has been extensively studied, and genetic and molecular tools such as reporter gene systems for the measurement of fungal growth have been developed. A reporter construct containing the Aspergillus flavus β-tubulin gene promoter fused to Escherichia coli β-glucuronidase (GUS) has been shown to be a reliable tool for the indirect measurement of fungal growth in maize kernels. Since cost-saving alternative methods for the direct measurement of aflatoxin levels are needed to facilitate more widespread field and laboratory screening of maize lines, a new reporter gene construct involving the promoter region of the omtA gene of the aflatoxin biosynthetic pathway was constructed and tested. Expression of GUS activity by this construct (omtA::GUS) was correlated with aflatoxin accumulation in culture. In the fungal transformant GAP26-1, which harbors this construct, aflatoxin production and GUS expression on sucrose-containing medium showed the same temporal pattern of toxin induction. Furthermore, GUS expression by GAP26-1 was shown to be associated with aflatoxin accumulation in maize kernels inoculated with this strain. Our results suggest that this and other reporter gene pathway promoter constructs may provide superior alternatives to direct aflatoxin quantification with respect to time, labor, and materials for the screening of maize lines for resistance to aflatoxin accumulation.

Growth of an Aspergillus flavus Transformant Expressing Escherichia coli β-Glucuronidase in Maize Kernels Resistant to Aflatoxin Production

1997 ◽  
Vol 60 (1) ◽  
pp. 84-87 ◽  
Author(s):  
ROBERT L. BROWN ◽  
THOMAS E. CLEVELAND ◽  
GARY A. PAYNE ◽  
CHARLES P. WOLOSHUK ◽  
DONALD G. WHITE
Keyword(s):  
Escherichia Coli ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Gene Promoter ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Glucuronidase Activity ◽  
Glucuronidase Reporter ◽  
Aflatoxin Accumulation ◽  
Maize Kernels

Kernels of a maize inbred that demonstrated resistance to aflatoxin production in previous studies were inoculated with an Aspergillus flavus strain containing the Escherichia coli β-d-glucuronidase reporter gene linked to a β-tubulin gene promoter and assessed for both fungal growth and aflatoxin accumulation. Prior to inoculation, kernels were pin-wounded through the pericarp to the endosperm, pin-wounded in the embryo region, or left unwounded. After 7 days incubation with the fungus, β-glucuronidase activity (fungal growth) in the kernels was quantified using a fluorogenic assay and aflatoxin B1 content of the same kernels was analyzed. Kernels of a susceptible inbred, similarly treated, served as controls. Results indicate a positive relationship between aflatoxin levels and the amount of fungal growth. However, resistant kernels wounded through the pericarp to the endosperm before inoculation supported an increase in aflatoxin B1 over levels observed in nonwounded kernels, without an increase in fungal growth. Wounding kernels of the resistant inbred through the embryo resulted in both the greatest fungal growth and the highest levels of aflatoxin B1 for this genotype. Maintenance of resistance to aflatoxin B1 in endosperm-wounded kernels may be due to the action of a mechanism which limits fungal access to the kernel embryo.

A Maize Trypsin Inhibitor (ZmTIp) with Limited Activity against Aspergillus flavus

2009 ◽  
Vol 72 (1) ◽  
pp. 185-188 ◽  
Author(s):  
R. L. BAKER ◽  
R. L. BROWN ◽  
Z.-Y. CHEN ◽  
T. E. CLEVELAND ◽  
A. M. FAKHOURY
Keyword(s):  
Aspergillus Flavus ◽  
Fungal Pathogens ◽  
Fungal Growth ◽  
Hyphal Growth ◽  
Sources Of Resistance ◽  
Potential Source ◽  
Maize Genotypes ◽  
Aflatoxin Accumulation

Infection of maize both pre- and postharvest by Aspergillus flavus is a severe agricultural problem in the southern United States. Aflatoxins are secondary metabolites produced by A. flavus and are carcinogenic to humans and animals upon ingestion. Extensive research has been conducted to identify sources of resistance to A. flavus in maize. Some maize genotypes exhibit greater resistance to A. flavus than others. Many research groups have validated the role of plant trypsin inhibitors (TIs) as a means of plant defense against fungal infection. Research consisting of the cloning, expression, and partial characterization of one previously uncharacterized TI protein has been conducted. The overexpressed protein displayed TI activity, as expected, and some ability to alter germination of conidia (8%) from several fungal pathogens and to inhibit hyphal growth (30%). This effect on fungal growth, although less than that of previously investigated TIs, marks this protein as a potential source of resistance to aflatoxin accumulation in maize.

scholarly journals Competency of Clove and Cinnamon Essential Oil Fumigation against Toxigenic and Atoxigenic Aspergillus flavus Isolates

2021 ◽  
Author(s):  
Sansern Rangsuwan ◽  
Chainarong Rattanakreetakul ◽  
Ratiya Pongpisutta
Keyword(s):  
Essential Oil ◽  
Essential Oils ◽  
Aspergillus Flavus ◽  
Fungal Growth ◽  
Culture Broth ◽  
Membrane Injury ◽  
Cinnamon Oil ◽  
Hyphal Morphology ◽  
Aflatoxin Accumulation ◽  
Cinnamon Essential Oil

Aspergillus flavus is a frequent contaminant of maize grain. We isolated this fungus, determined the colony morphology and species (by internal transcribed spacer sequencing) and measured the aflatoxin content. The selected A. flavus fungi were placed into two groups, toxigenic and atoxigenic; both appeared similar morphologically, except that the atoxigenic group lacked sclerotia. An essential oil fumigation test with clove and cinnamon oils as antifungal products was performed on fungal conidial discs and fungal colonies in Petri plates. Cinnamon oil at 2.5 to 5.0 μL/plate markedly inhibited the mycelial growth from conidial discs of both strains, whereas clove oil showed less activity. The oils had different effects on fungal mycelia. The higher clove fumigation doses of 10.0 to 20.0 μL/plate controlled fungal growth, while cinnamon oil caused less inhibition. Compared with atoxigenic groups, toxigenic A. flavus responded stably. Within abnormal A. flavus hyphae, the essential oils degenerated the hyphal morphology, resulting in exfoliated flakes and shrinkage, which were related to fungal membrane injury and collapse of vacuoles and phialide. The treatments, especially those with cinnamon oil, increased the electroconductivity, which suggested a weak mycelium membrane structure. Moreover, the treatments with essential oils reduced the ergosterol content in mycelia and the aflatoxin accumulation in the culture broth. The fumigations with clove and cinnamon oils inhibited the development of both conidia and colonies of A. flavus in dose-dependent manners.

The content of decenoic acids in drone brood preparations and combined preparations based on it

Biomics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 389-393
Author(s):  
D.V. Mitrofanov ◽  
N.V. Budnikova
Keyword(s):  
Royal Jelly ◽  
Storage Conditions ◽  
Water Soluble ◽  
Biologically Active Substances ◽  
Biologically Active ◽  
Strict Adherence ◽  
Drone Brood ◽  
Wide Range ◽  
Active Substances ◽  
Melanin Complex

The drone brood contains a large number of substances with antioxidant activity. These substances require stabilization and strict adherence to storage conditions. Among these substances are unique decenoic acids, the content of which is an indicator of the quality of drone brood and products based on it. The ability of drone brood to reduce the manifestations of oxidative stress is shown. There are dietary supplements for food and drugs based on drone brood, which are used for a wide range of diseases. Together with drone brood, chitosan-containing products, propolis, royal jelly can be used. They enrich the composition with their own biologically active substances and affect the preservation of the biologically active substances of the drone brood. Promising are the products containing, in addition to the drone brood, a chitin-chitosan-melanin complex from bees, propolis, royal jelly. The chitin-chitosan-melanin complex in the amount of 5% in the composition of the adsorbent practically does not affect the preservation of decenic acids, while in the amount of 2% and 10% it somewhat worsens. The acid-soluble and water-soluble chitosan of marine crustaceans significantly worsens the preservation of decenoic acids in the product. Drone brood with royal jelly demonstrates a rather high content of decenoic acids. When propolis is introduced into the composition of the product, the content of decenoic acids increases according to the content of propolis.

scholarly journals Mimosa tenuiflora Aqueous Extract: Role of Condensed Tannins in Anti-Aflatoxin B1 Activity in Aspergillus flavus

Toxins ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 391
Author(s):  
Christopher Hernandez ◽  
Laura Cadenillas ◽  
Anwar El Maghubi ◽  
Isaura Caceres ◽  
Vanessa Durrieu ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Aqueous Extract ◽  
Aflatoxin B1 ◽  
Condensed Tannins ◽  
Fungal Growth ◽  
Oxidation Reactions ◽  
Expression Of Genes ◽  
Dependent Inhibition ◽  
Interesting Candidate ◽  
Mimosa Tenuiflora

Aflatoxin B1 (AFB1) is a potent carcinogenic mycotoxin that contaminates numerous crops pre- and post-harvest. To protect foods and feeds from such toxins without resorting to pesticides, the use of plant extracts has been increasingly studied. The most interesting candidate plants are those with strong antioxidative activity because oxidation reactions may interfere with AFB1 production. The present study investigates how an aqueous extract of Mimosa tenuiflora bark affects both the growth of Aspergillus flavus and AFB1 production. The results reveal a dose-dependent inhibition of toxin synthesis with no impact on fungal growth. AFB1 inhibition is related to a down-modulation of the cluster genes of the biosynthetic pathway and especially to the two internal regulators aflR and aflS. Its strong anti-oxidative activity also allows the aqueous extract to modulate the expression of genes involved in fungal oxidative-stress response, such as msnA, mtfA, atfA, or sod1. Finally, a bio-guided fractionation of the aqueous extract demonstrates that condensed tannins play a major role in the anti-aflatoxin activity of Mimosa tenuiflora bark.

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