Aspergillus flavus and Aflatoxin Contamination of Leguminous Trees of the Sonoran Desert in Arizona

Aspergillus spp. in section Flavi were frequently associated with desert tree legumes in uncultivated areas of the Sonoran Desert. Of 270 samples of debris and fruits of mesquite (Prosopis spp.), ironwood (Olneya tesota), acacia (Acacia spp.), and palo verde (Cercidium and Parkinsonia spp.), 87% were positive for A. flavus (S and L strains) and A. tamarii. A. flavus was the most common species (87%) among the 3,763 isolates examined. Mesquite pods were both the substrate from which A. flavus was recovered most frequently and the substrate from native habitats with the greatest aflatoxin content. In vitro, most desert legumes supported significant growth, reproduction, and aflatoxin production by A. flavus, with mesquite pods yielding 1 × 1010 propagules/g and 5,000 μg/kg of aflatoxin B1. Twenty percent of legume pods collected in the desert contained measurable quantities of aflatoxin, ranging from 1 to >2,500 μg/kg. Insect-damaged mesquite pods had significantly higher aflatoxin than intact pods. Legumes are apparently important reservoirs of aflatoxin-producing fungi and significant sources of aflatoxin contamination in the native Sonoran Desert habitats of Arizona.

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In Vitro Activity of Balanites aegyptiaca and Tamarindus indica Fruit Extracts on Growth and Aflatoxigenicity of Aspergillus flavus and A. parasiticus

Journal of Food Research ◽

10.5539/jfr.v2n4p68 ◽

2013 ◽

Vol 2 (4) ◽

pp. 68 ◽

Cited By ~ 1

Author(s):

Saifeldin Ahmed El-nagerabi ◽

Abdulkadir E. Elshafie ◽

Mohamed R. Elamin

Keyword(s):

Aspergillus Flavus ◽

Fungal Growth ◽

Aflatoxin Contamination ◽

Tamarindus Indica ◽

Balanites Aegyptiaca ◽

Total Aflatoxin ◽

Animal Products ◽

Fruit Extracts ◽

Aflatoxin B

Aflatoxin and especially aflatoxin B1 (AFB1) is a carcinogenic secondary metabolite synthesized by certain Aspergillus species. They contaminate natural and processed agricultural and animal products which render them unfit for consumption. The aim of this study was to evaluate the in vitro effects of Balanites aegyptiaca and Tamarindus indica fruit extracts on the growth and aflatoxin secretion of Aspergillus flavus (SQU21) and A. parasiticus (CBS921.7) strains. The two fruit extracts significantly (P < 0.05) reduced aflatoxin and did not inhibit mycelial dry weights of the two Aspergillus strains. At different concentrations of balanites (2.5-10%), the inhibition of total aflatoxin was 49.9-84.8% for A. flavus (SQU21) and 32.1-84.4% for A. parasiticus (CBS921.7), whereas the inhibition of aflatoxin Bwas 38.2-81.4% and 32.8-80.6% for the two strains. Tamarind fruit extract (2.5-7.5%) caused 28.8-84.2% and 40.7-85.5% reductions in total aflatoxin and 37.1-83.5% and 33.9-85.9% in aflatoxin B for the two strains, respectively. None of these extracts inhibited the fungal growth or detoxified synthetic aflatoxin B1. We have concluded that these fruits contain various inhibitors to aflatoxin biosynthesis and secretion. Therefore, they can be used in combination as safe green biopreservatives to combat aflatoxin contamination of food.

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Assessment of the Effect of Satureja montana and Origanum virens Essential Oils on Aspergillus flavus Growth and Aflatoxin Production at Different Water Activities

Toxins ◽

10.3390/toxins12030142 ◽

2020 ◽

Vol 12 (3) ◽

pp. 142 ◽

Cited By ~ 3

Author(s):

Marta García-Díaz ◽

Jessica Gil-Serna ◽

Belén Patiño ◽

Esther García-Cela ◽

Naresh Magan ◽

...

Keyword(s):

Essential Oil ◽

Essential Oils ◽

Aspergillus Flavus ◽

Aflatoxin Production ◽

Aflatoxin Contamination ◽

Activity Levels ◽

Control Methods ◽

Mycotoxin Biosynthesis ◽

Satureja Montana

Aflatoxin contamination of foodstuffs poses a serious risk to food security, and it is essential to search for new control methods to prevent these toxins entering the food chain. Several essential oils are able to reduce the growth and mycotoxin biosynthesis of toxigenic species, although their efficiency is strongly influenced by the environmental conditions. In this work, the effectiveness of Satureja montana and Origanum virens essential oils to control Aspergillus flavus growth was evaluated under three water activity levels (0.94, 0.96 and 0.98 aw) using a Bioscreen C, a rapid in vitro spectrophotometric technique. The aflatoxin concentrations at all conditions tested were determined by HPLC-FLD. Aspergillus flavus growth was delayed by both essential oil treatments. However, only S. montana essential oil was able to significantly affect aflatoxin production, although the inhibition percentages widely differed among water activities. The most significant reduction was observed at 0.96 aw, which is coincident with the conditions in which A. flavus reached the highest levels of aflatoxin production. On the contrary, the treatment with S. montana essential oil was not effective in significantly reducing aflatoxin production at 0.94 aw. Therefore, it is important to study the interaction of the new control compounds with environmental factors before their application in food matrices, and in vitro ecophysiological studies are a good option since they provide accurate and rapid results.

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Aspergillus flavus NRRL 3251 Growth, Oxidative Status, and Aflatoxins Production Ability In Vitro under Different Illumination Regimes

Toxins ◽

10.3390/toxins10120528 ◽

2018 ◽

Vol 10 (12) ◽

pp. 528 ◽

Cited By ~ 5

Author(s):

Tihomir Kovač ◽

Bojan Šarkanj ◽

Biljana Crevar ◽

Marija Kovač ◽

Ante Lončarić ◽

...

Keyword(s):

Aspergillus Flavus ◽

Growth Period ◽

Aflatoxin Production ◽

Aflatoxin Contamination ◽

Oxidative Status ◽

Light Illumination ◽

Proper Understanding ◽

Experimental Strains ◽

Oxidative Species

Aspergillus flavus is the most important mycotoxin-producing fungus involved in the global episodes of aflatoxin B1 contamination of crops at both the pre-harvest and post-harvest stages. However, in order to effectively control aflatoxin contamination in crops using antiaflatoxigenic and/or antifungal compounds, some of which are photosensitive, a proper understanding of the photo-sensitive physiology of potential experimental strains need to be documented. The purpose of the study is therefore to evaluate the effect of visible (VIS) light illumination on growth and conidiation, aflatoxin production ability and modulation of A. flavus oxidative status during in vitro experiment. Aflatoxigenic A. flavus strain was inoculated in aflatoxin-inducing YES media and incubated under three different VIS illumination regimes during a 168 h growth period at 29 °C. VIS illumination reduced A. flavus mycelia biomass yield, both during growth on plates and in liquid media, promoted conidiation and increased the aflatoxin production. Furthermore, aflatoxin production increased with increased reactive oxidative species (ROS) levels at 96 h of growth, confirming illumination-driven oxidative stress modulation activity on A. flavus cells.

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Activity and Anti-Aflatoxigenic Effect of Indigenously Characterized Probiotic Lactobacilli against Aspergillus flavus—A Common Poultry Feed Contaminant

Animals ◽

10.3390/ani9040166 ◽

2019 ◽

Vol 9 (4) ◽

pp. 166 ◽

Cited By ~ 2

Author(s):

Nimra Azeem ◽

Muhammad Nawaz ◽

Aftab Ahmad Anjum ◽

Shagufta Saeed ◽

Saba Sana ◽

...

Keyword(s):

Aspergillus Flavus ◽

High Performance ◽

Animal Feed ◽

Aflatoxin Production ◽

Aflatoxin Contamination ◽

Poultry Feed ◽

Poultry Production ◽

Ameliorative Effect ◽

Probiotic Lactobacilli

Aflatoxin contamination in human food and animal feed is a threat to public safety. Aflatoxin B1 (AFB1) can be especially damaging to poultry production and consequently economic development of Pakistan. The present study assessed the in vitro binding of AFB1 by indigenously characterized probiotic lactobacilli. Six isolates (Lactobacillus gallinarum PDP 10, Lactobacillus reuetri FYP 38, Lactobacillus fermentum PDP 24, Lactobacillus gallinarum PL 53, Lactobacillus paracasei PL 120, and Lactobacillus gallinarum PL 149) were tested for activity against toxigenic Aspergillus flavus W-7.1 (AFB1 producer) by well diffusion assay. Only three isolates (PL 53, PL 120, and PL 149) had activity against A. flavus W-7.1. The ameliorative effect of these probiotic isolates on AFB1 production was determined by co-culturing fungus with lactobacilli for 12 days, followed by aflatoxin quantification by high-performance liquid chromatography. In vitro AFB1 binding capacities of lactobacilli were determined by their incubation with a standard amount of AFB1 in phosphate buffer saline at 37 °C for 2 h. AFB1 binding capacities of isolates ranged from 28–65%. Four isolates (PDP 10, PDP 24, PL 120, and PL 149) also ceased aflatoxin production completely, whereas PL 53 showed 55% reduction in AFB1 production as compared to control. The present study demonstrated Lactobacillus gallinarum PL 149 to be an effective candidate AFB1 binding agent against Aspergillus flavus. These findings further support the binding ability of lactic acid bacteria for dietary contaminants.

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A Novel Niosome-Encapsulated Essential Oil Formulation to Prevent Aspergillus flavus Growth and Aflatoxin Contamination of Maize Grains During Storage

Toxins ◽

10.3390/toxins11110646 ◽

2019 ◽

Vol 11 (11) ◽

pp. 646 ◽

Cited By ~ 6

Author(s):

García-Díaz ◽

Patiño ◽

Vázquez ◽

Gil-Serna

Keyword(s):

Aspergillus Flavus ◽

Fungal Growth ◽

Storage Conditions ◽

Aflatoxin Contamination ◽

Small Scale ◽

Low Concentrations ◽

Oil Formulation ◽

Scale Test ◽

Encapsulation Method

Aflatoxin (AF) contamination of maize is a major concern for food safety. The use of chemical fungicides is controversial, and it is necessary to develop new effective methods to control Aspergillus flavus growth and, therefore, to avoid the presence of AFs in grains. In this work, we tested in vitro the effect of six essential oils (EOs) extracted from aromatic plants. We selected those from Satureja montana and Origanum virens because they show high levels of antifungal and antitoxigenic activity at low concentrations against A. flavus. EOs are highly volatile compounds and we have developed a new niosome-based encapsulation method to extend their shelf life and activity. These new formulations have been successfully applied to reduce fungal growth and AF accumulation in maize grains in a small-scale test, as well as placing the maize into polypropylene woven bags to simulate common storage conditions. In this latter case, the antifungal properties lasted up to 75 days after the first application.

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Control of Aspergillus flavus and aflatoxin production with spices in culture medium and rice

World Mycotoxin Journal ◽

10.3920/wmj2012.1437 ◽

2013 ◽

Vol 6 (1) ◽

pp. 43-50 ◽

Cited By ~ 6

Author(s):

V. Aiko ◽

A. Mehta

Keyword(s):

Aspergillus Flavus ◽

High Performance ◽

Fungal Growth ◽

Aflatoxin Production ◽

Culture Broth ◽

Minimum Inhibitory Concentrations ◽

Food Grains ◽

Star Anise ◽

Aflatoxin B ◽

Layer Chromatography

Cinnamon, cardamom, star anise and clove were studied for their effect on growth of Aspergillus flavus and aflatoxin B1 (AFB1) synthesis. The experiments were carried out in yeast extract sucrose culture broth as well as in rice supplemented with spices. AFB1 produced was analysed qualitatively and quantitatively using thin layer chromatography and high performance liquid chromatography, respectively. At a concentration of 10 mg/ml, cardamom and star anise did not exhibit any antifungal or anti-aflatoxigenic activity in culture broth, whereas cinnamon and clove inhibited A. flavus growth completely. The minimum inhibitory concentrations of cinnamon and clove were 4 and 2 mg/ml, respectively. Concentrations of cinnamon and clove below their minimum inhibitory concentrations showed enhanced fungal growth, while AFB1 synthesis was reduced. Clove inhibited the synthesis of AFB1 significantly up to 99% at concentrations ≥1.0 mg/ml. The spices also inhibited AFB1 synthesis in rice at 5 mg/g, although fungal growth was not inhibited. Clove and cinnamon inhibited AFB1 synthesis significantly up to 99 and 92%, respectively, and star anise and cardamom by 41 and 23%, respectively. The results of this study suggest the use of whole spices rather than their essential oils for controlling fungal and mycotoxin contamination in food grains.

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Interactions of Saprophytic Yeasts with anor Mutant of Aspergillus flavus

Applied and Environmental Microbiology ◽

10.1128/aem.65.6.2738-2740.1999 ◽

1999 ◽

Vol 65 (6) ◽

pp. 2738-2740 ◽

Cited By ~ 47

Author(s):

Sui-Sheng T. Hua ◽

James L. Baker ◽

Melanie Flores-Espiritu

Keyword(s):

Aspergillus Flavus ◽

Agar Plate ◽

Aflatoxin Production ◽

Aflatoxin Contamination ◽

Orange Pigment ◽

Yeast Strains ◽

Norsolorinic Acid ◽

Aflatoxin Accumulation ◽

Food Commodities ◽

Pigment Accumulation

ABSTRACT The nor mutant of Aspergillus flavus has a defective norsolorinic acid reductase, and thus the aflatoxin biosynthetic pathway is blocked, resulting in the accumulation of norsolorinic acid, a bright red-orange pigment. We developed a visual agar plate assay to monitor yeast strains for their ability to inhibit aflatoxin production by visually scoring the accumulation of this pigment of the nor mutant. We identified yeast strains that reduced the red-orange pigment accumulation in the normutant. These yeasts also reduced aflatoxin accumulation by a toxigenic strain of A. flavus. These yeasts may be useful for reducing aflatoxin contamination of food commodities.

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No Effect of Soybean Lipoxygenase on Aflatoxin Production in Aspergillus flavus–Inoculated Seeds

Journal of Food Protection ◽

10.4315/0362-028x-65.12.1984 ◽

2002 ◽

Vol 65 (12) ◽

pp. 1984-1987 ◽

Cited By ~ 6

Author(s):

J. E. MELLON ◽

P. J. COTTY

Keyword(s):

Aspergillus Flavus ◽

Fungal Pathogens ◽

Seed Viability ◽

Soybean Seed ◽

Fungal Growth ◽

Aflatoxin Production ◽

Aflatoxin Contamination ◽

Soybean Seeds ◽

Heat Treated ◽

Significant Difference

Soybean lines lacking lipoxygenase (LOX) activity were compared with soybean lines having LOX activity for the ability to support growth and aflatoxin B1 production by the fungal seed pathogen Aspergillus flavus. Whole seeds, broken seeds, and heat-treated (autoclaved) whole seeds were compared. Broken seeds, irrespective of LOX presence, supported excellent fungal growth and the highest aflatoxin levels. Autoclaved whole seeds, with or without LOX, produced good fungal growth and aflatoxin levels approaching those of broken seeds. Whole soybean seeds supported sparse fungal growth and relatively low aflatoxin levels. There was no significant difference in aflatoxin production between whole soybean seeds either with or without LOX, although there did seem to be differences among the cultivars tested. The heat treatment eliminated LOX activity (in LOX+ lines), yet aflatoxin levels did not change substantially from the broken seed treatment. Broken soybean seeds possessed LOX activity (in LOX+ lines) and yet yielded the highest aflatoxin levels. The presence of active LOX did not seem to play the determinant role in the susceptibility of soybean seeds to fungal pathogens. Seed coat integrity and seed viability seem to be more important characteristics in soybean seed resistance to aflatoxin contamination. Soybean seeds lacking LOX seem safe from the threat of increased seed pathogen susceptibility.

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The Frequency of Sex: Population Genomics Reveals Differences in Recombination and Population Structure of the Aflatoxin-Producing Fungus Aspergillus flavus

mBio ◽

10.1128/mbio.00963-20 ◽

2020 ◽

Vol 11 (4) ◽

Cited By ~ 3

Author(s):

Milton T. Drott ◽

Tatum R. Satterlee ◽

Jeffrey M. Skerker ◽

Brandon T. Pfannenstiel ◽

N. Louise Glass ◽

...

Keyword(s):

Aspergillus Flavus ◽

Population Genomics ◽

Population Expansion ◽

Aflatoxin Production ◽

The United States ◽

Aflatoxin Contamination ◽

Deleterious Mutations ◽

Content Type ◽

Sexual And Asexual Reproduction ◽

Potent Carcinogen

ABSTRACT The apparent rarity of sex in many fungal species has raised questions about how much sex is needed to purge deleterious mutations and how differences in frequency of sex impact fungal evolution. We sought to determine how differences in the extent of recombination between populations of Aspergillus flavus impact the evolution of genes associated with the synthesis of aflatoxin, a notoriously potent carcinogen. We sequenced the genomes of, and quantified aflatoxin production in, 94 isolates of A. flavus sampled from seven states in eastern and central latitudinal transects of the United States. The overall population is subdivided into three genetically differentiated populations (A, B, and C) that differ greatly in their extent of recombination, diversity, and aflatoxin-producing ability. Estimates of the number of recombination events and linkage disequilibrium decay suggest relatively frequent sex only in population A. Population B is sympatric with population A but produces significantly less aflatoxin and is the only population where the inability of nonaflatoxigenic isolates to produce aflatoxin was explained by multiple gene deletions. Population expansion evident in population B suggests a recent introduction or range expansion. Population C is largely nonaflatoxigenic and restricted mainly to northern sampling locations through restricted migration and/or selection. Despite differences in the number and type of mutations in the aflatoxin gene cluster, codon optimization and site frequency differences in synonymous and nonsynonymous mutations suggest that low levels of recombination in some A. flavus populations are sufficient to purge deleterious mutations. IMPORTANCE Differences in the relative frequencies of sexual and asexual reproduction have profound implications for the accumulation of deleterious mutations (Muller’s ratchet), but little is known about how these differences impact the evolution of ecologically important phenotypes. Aspergillus flavus is the main producer of aflatoxin, a notoriously potent carcinogen that often contaminates food. We investigated if differences in the levels of production of aflatoxin by A. flavus could be explained by the accumulation of deleterious mutations due to a lack of recombination. Despite differences in the extent of recombination, variation in aflatoxin production is better explained by the demography and history of specific populations and may suggest important differences in the ecological roles of aflatoxin among populations. Furthermore, the association of aflatoxin production and populations provides a means of predicting the risk of aflatoxin contamination by determining the frequencies of isolates from low- and high-production populations.

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Staphylococcus saprophyticus L-38 produces volatile 3,3-dimethyl-1,2-epoxybutane with strong inhibitory activity against Aspergillus flavus germination and aflatoxin production

World Mycotoxin Journal ◽

10.3920/wmj2019.2495 ◽

2020 ◽

Vol 13 (2) ◽

pp. 247-258 ◽

Cited By ~ 1

Author(s):

A.D. Gong ◽

G.J. Sun ◽

Z.Y. Zhao ◽

Y.C. Liao ◽

J.B. Zhang

Keyword(s):

Food Safety ◽

Antifungal Activity ◽

Aspergillus Flavus ◽

Plant Pathogens ◽

Aflatoxin Production ◽

Gas Chromatography Mass Spectrometry ◽

Total Peak Area ◽

Staphylococcus Saprophyticus

Controlling proliferation and aflatoxin production by Aspergillus flavus is a pressing challenge for global food safety and security. Marine bacterium Staphylococcus saprophyticus strain L-38 showed excellent antifungal activity toward A. flavus in vitro and in vivo. In sealed, non-contact confrontation assays, L-38 completely inhibited conidial germination and mycelial growth of A. flavus through the production of volatile organic compounds (VOCs). Gas chromatography-mass spectrometry identified 3,3-dimethyl-1,2-epoxybutane (3-DE) as the most abundant VOC (32.61% of total peak area, 78% matching). Exposure of A. flavus cultures to synthetic 3-DE similarly demonstrated strong inhibition of growth. Moreover, culture of L-38 in a sealed chamber with maize or peanuts artificially inoculated with A. flavus, at high water activity, resulted in significant inhibition of A. flavus germination and aflatoxin biosynthesis. Scanning electron microscopy of these samples revealed severe damage to conidial cells and hyphae compared to samples not exposed to L-38. L-38 also showed broad and effective antifungal activity toward eight other phytopathogenic fungi including Aspergillus niger, Fusarium verticillioides, Fusarium graminearum, Sclerotinia sclerotiorum, Rhizoctonia solani, Alternaria alternata, Monilinia fructicola, and Botrytis cinerea. This work introduces S. saprophyticus L-38 as a potential biocontrol agent and demonstrates the efficacy of the volatile 3-DE in the control of A. flavus and other destructive plant pathogens for post-harvest food safety.

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