Non-aflatoxigenic Aspergillus flavus as potential biocontrol agents to reduce aflatoxin contamination in peanuts harvested in Northern Argentina

Aspergillus flavus, a haploid organism found worldwide in a variety of crops, including maize, cottonseed, almond, pistachio, and peanut, causes substantial and recurrent worldwide economic liabilities. This filamentous fungus produces aflatoxins (AFLs) B1 and B2, which are among the most carcinogenic compounds from nature, acutely hepatotoxic and immunosuppressive. Recent efforts to reduce AFL contamination in crops have focused on the use of nonaflatoxigenic A. flavus strains as biological control agents. Such agents are applied to soil to competitively exclude native AFL strains from crops and thereby reduce AFL contamination. Because the possibility of genetic recombination in A. flavus could influence the stability of biocontrol strains with the production of novel AFL phenotypes, this article assesses the diversity of vegetative compatibility reactions in isolates of A. flavus to identify heterokaryon self-incompatible (HSI) strains among nonaflatoxigenic isolates, which would be used as biological controls of AFL contamination in crops. Nitrate nonutilizing (nit) mutants were recovered from 25 A. flavus isolates, and based on vegetative complementation between nit mutants and on the microscopic examination of the number of hyphal fusions, five nonaflatoxigenic (6, 7, 9 to 11) and two nontoxigenic (8 and 12) isolates of A. flavus were phenotypically characterized as HSI. Because the number of hyphal fusions is reduced in HSI strains, impairing both heterokaryon formation and the genetic exchanges with aflatoxigenic strains, the HSI isolates characterized here, especially isolates 8 and 12, are potential agents for reducing AFL contamination in crops.

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Revisiting an Aspergillus flavus Strain Isolated from an Egyptian Sugarcane Field in 1930

Microorganisms ◽

10.3390/microorganisms8111633 ◽

2020 ◽

Vol 8 (11) ◽

pp. 1633

Author(s):

Mohamed F. Abdallah ◽

Kris Audenaert ◽

Sarah De Saeger ◽

Jos Houbraken

Keyword(s):

Aspergillus Flavus ◽

Short Communication ◽

Aflatoxin Contamination ◽

Type B ◽

Prevention Strategies ◽

Sugarcane Field ◽

Host Pathogen Interaction ◽

Sugarcane Crop ◽

Insight Into ◽

Shed Light

The aflatoxin type B and G producer Aspergillus novoparasiticus was described in 2012 and was firstly reported from sputum, hospital air (Brazil), and soil (Colombia). Later, several survey studies reported the occurrence of this species in different foods and other agricultural commodities from several countries worldwide. This short communication reports on an old fungal strain (CBS 108.30), isolated from Pseudococcus sacchari (grey sugarcane mealybug) from an Egyptian sugarcane field in (or before) 1930. This strain was initially identified as Aspergillus flavus; however, using the latest taxonomy schemes, the strain is, in fact, A. novoparasiticus. These data and previous reports indicate that A. novoparasiticus is strongly associated with sugarcane, and pre-harvest biocontrol approaches with non-toxigenic A. novoparasiticus strains are likely to be more successful than those using non-toxigenic A. flavus strains. Further studies on the association between A. novoparasiticus and Pseudococcus sacchari might shed light on the distribution (and aflatoxin contamination) of this species in sugarcane. Additionally, the interaction between A. novoparasiticus, Pseudococcus sacchari, and sugarcane crop under different scenarios of climate change will be critical in order to get more insight into the host–pathogen interaction and host resistance and propose appropriate prevention strategies to decrease mycotoxin contamination and crop loss due to A. novoparasiticus attack.

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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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Modelling the colonisation of maize by toxigenic and non-toxigenic Aspergillus flavus strains: implications for biological control

World Mycotoxin Journal ◽

10.3920/wmj2008.x036 ◽

2008 ◽

Vol 1 (3) ◽

pp. 333-340 ◽

Cited By ~ 17

Author(s):

H. Abbas ◽

R. Zablotowicz ◽

H. Bruns

Keyword(s):

Biological Control ◽

Aspergillus Flavus ◽

Growth Parameters ◽

Biological Control Agent ◽

Cyclopiazonic Acid ◽

Aflatoxin Contamination ◽

Tween 20 ◽

Lag Phase ◽

Gompertz Equation ◽

Aflatoxin Accumulation

To successfully exploit biological control it is desirable to understand how the introduced agent colonises the host and interferes with establishment of the pest. This study assessed field colonisation of maize by Aspergillus flavus strains as biological control agents to reduce aflatoxin contamination. Maize (corn, Zea mays L.) ears were inoculated with A. flavus using a pin-bar technique in 2004 and 2005. Non-aflatoxigenic strains K49 (NRRL 30797) & CT3 (NRRL 30798) and toxigenic F3W4 (NRRL 30798) were compared against a carrier control (0.2% aqueous Tween 20). Ten ears were sampled over 12 to 20 days, visually assessed, and curves fit to a three compartment Gompertz equation or other best appropriate regressions. Aflatoxin was determined by HPLC and cyclopiazonic acid (CPA) by LC/MS. The Gompertz model describes growth parameters, e.g. growth constant, lag phase and maximum colonisation characterised patterns of maize colonisation for most inoculated treatments. Aflatoxin accumulation in maize inoculated with F3W4 was about 35,000 ng/g in 2004 and 2005, with kinetics of aflatoxin accumulation in 2005 well described by the Gompertz equation. Less than 200 ng/g was observed in maize inoculated with strains CT3 & K49 and accumulation was described by a linear or logistic model. Maize inoculated with strains CT3 and F3W4 accumulated a maximum of 220 and 169 µg/kg CPA, respectively, compared to 22 and 0.2 µg/kg in the control and K49 inoculated, respectively. This technique can be used to elucidate colonisation potential of non-toxigenic A. flavus in maize in relation to biological control of aflatoxin. The greatest reduction of aflatoxin and CPA in maize inoculated with strain K49 and Gompertz parameters on colonisation indicates its superiority to CT3 as a biological control agent. The dynamics of maize colonisation by A. flavus strains and subsequent mycotoxin accumulation generated by using the pin-bar technique has implications for characterising the competence of biocontrol strains for reducing aflatoxin contamination.

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Evaluation of resistance to aflatoxin contamination in kernels of maize genotypes using a GFP-expressing Aspergillus flavus strain

World Mycotoxin Journal ◽

10.3920/wmj2012.1497 ◽

2013 ◽

Vol 6 (2) ◽

pp. 151-158 ◽

Cited By ~ 12

Author(s):

K. Rajasekaran ◽

C.M. Sickler ◽

R.L. Brown ◽

J.W. Cary ◽

D. Bhatnagar

Keyword(s):

Fungal Infection ◽

Aspergillus Flavus ◽

Fluorescent Protein ◽

Aflatoxin Contamination ◽

Clear Correlation ◽

Aleurone Layer ◽

Screening Assay ◽

Maize Germplasm ◽

Antifungal Proteins ◽

Green Fluorescent

Resistance or susceptibility of maize inbreds to infection by Aspergillus flavus was evaluated by the kernel screening assay. A green fluorescent protein-expressing strain of A. flavus was used to measure fungal spread and aflatoxin levels in real-time following fungal infection of kernels. Among the four inbreds tested, MI82 showed the most resistance and Ga209 the least. TZAR101 was also resistant to fungal infection, whereas Va35 was susceptible to fungal infection. However, Va35 produced lower aflatoxin levels compared to the susceptible line Ga209. Fluorescence microscopy indicated that the site of entry of the fungus into the kernel was consistently through the pedicel. Entry through the pericarp was never observed in undamaged kernels. In view of these results, incorporation or overexpression of antifungal proteins should be targeted to the pedicel and basal endosperm region in developing kernels. Once the fungus has entered through the pedicel, it spreads quickly through the open spaces between the pericarp and the aleurone layer, ultimately colonising the endosperm and scutellum and, finally, the embryo. A clear correlation was established between fungal fluorescence and aflatoxin levels. This method provides a quick, reliable means of evaluating resistance to A. flavus in undamaged kernels and provides breeders with a rapid method to evaluate maize germplasm.

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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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Aspergillus Colonization and Aflatoxin Contamination in Peanut Genotypes with Resistance to Other Fungal Pathogens

Plant Disease ◽

10.1094/pdis.1997.81.12.1429 ◽

1997 ◽

Vol 81 (12) ◽

pp. 1429-1431 ◽

Cited By ~ 8

Author(s):

C. Corley Holbrook ◽

David M. Wilson ◽

Michael E. Matheron ◽

William F. Anderson

Keyword(s):

Drought Stress ◽

Aspergillus Flavus ◽

Fungal Pathogens ◽

Sclerotium Rolfsii ◽

Indirect Selection ◽

Aflatoxin Contamination ◽

White Mold ◽

Mechanisms Of Resistance ◽

Selection Tool ◽

Aspergillus Flavus Group

Indirect selection tools would be valuable in the development of peanut (Arachis hypogaea) cultivars with resistance to aflatoxin contamination. The objective of this study was to determine whether resistance to other fungi could be used as an indirect selection tool for resistance to colonization of peanut by Aspergillus flavus group fungi or aflatoxin contamination. Nine peanut genotypes with resistance to late leaf spot (Cercosporidium personatum) or white mold (Sclerotium rolfsii) were evaluated for 2 years at Tifton, GA, and Yuma, AZ. Plots were subjected to late-season heat and drought stress. None of the genotypes exhibited less colonization of shells or kernels by A. flavus group fungi than cv. Florunner when tested in Georgia or Arizona. None of the genotypes showed a reduced level of aflatoxin contamination in comparison to Florunner at either location. These results indicate that the mechanisms of resistance to other fungi operating in these genotypes are not effective in providing resistance to colonization by A. flavus group fungi or reducing aflatoxin contamination. Therefore, resistance to these fungi cannot be used as an indirect selection tool for resistance to aflatoxin contamination.

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

PhytoFrontiers™ ◽

10.1094/phytofr-09-21-0067-r ◽

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.

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High-Density Genetic Linkage Map Construction Using Whole-Genome Resequencing for Mapping Qtls of Resistance to Aspergillus Flavus Infection in Peanut

10.21203/rs.3.rs-538664/v1 ◽

2021 ◽

Author(s):

Yifei Jiang ◽

Huaiyong Luo ◽

Bolun Yu ◽

Yingbin Ding ◽

Yanping Kang ◽

...

Keyword(s):

Linkage Map ◽

Aspergillus Flavus ◽

Genetic Linkage ◽

Genetic Basis ◽

Genetic Linkage Map ◽

Aflatoxin Contamination ◽

Whole Genome ◽

Genome Resequencing ◽

Favorable Alleles ◽

Whole Genome Resequencing

Abstract Cultivated peanut (Arachis hypogaea L.) is rich in edible oil and protein, which is widely planted around the world as an oil and cash crop. However, aflatoxin contamination seriously affects the quality safety of peanut, hindering the development of peanut industry and threatening consumers’ health. Breeding peanut varieties with resistance to Aspergillus flavus infection is important for control the aflatoxin contamination, and understanding of the genetic basis of resistance is vital to its genetic enhancement. In this study, we report the QTL mapping of resistance to A. flavus infection of a well-known resistant variety J11. A recombination inbred line (RIL) population was constructed by crossing a susceptible variety Zhonghua 16 and J11. Through whole-genome resequencing, a genetic linkage map was constructed with 2,802 recombination bins and an average inter-bin distance of 0.58 cM. Combined with phenotypic data of infection index in four consecutive years, six novel resistant QTLs were identified and they explained 5.03-10.87% phenotypic variances. The favorable alleles of five QTLs were from J11 while that of one QTL were from Zhonghua 16. The pyramiding of these favorable alleles significantly improved the resistance to A. flavus infection. These results could contribute greatly to understanding of genetic basis of A. flavus resistance and could be meaningful in further resistance improvement in peanut.

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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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