scholarly journals Characterization of Argentinian Endemic Aspergillus flavus Isolates and Their Potential Use as Biocontrol Agents for Mycotoxins in Maize

2018 ◽  
Vol 108 (7) ◽  
pp. 818-828 ◽  
Author(s):  
Boris X. Camiletti ◽  
Juan Moral ◽  
Claudia M. Asensio ◽  
Ada Karina Torrico ◽  
Enrique I. Lucini ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Cyclopiazonic Acid ◽  
Fungal Species ◽  
Biocontrol Agents ◽  
Vegetative Compatibility Groups ◽  
Quality Properties ◽  
Control Approach ◽  
Liquid Culture Medium ◽  
Maize Kernels ◽  
First Time

Maize (Zea mays L.) is a highly valuable crop in Argentina, frequently contaminated with the mycotoxins produced by Aspergillus flavus. Biocontrol products formulated with atoxigenic (nontoxic) strains of this fungal species are well known as an effective method to reduce this contamination. In the present study, 83 A. flavus isolates from two maize regions of Argentina were characterized and evaluated for their ability to produce or lack of producing mycotoxins in order to select atoxigenic strains to be used as potential biocontrol agents (BCA). All of the isolates were tested for aflatoxin and cyclopiazonic acid (CPA) production in maize kernels and a liquid culture medium. Genetic diversity of the nonaflatoxigenic isolates was evaluated by analysis of vegetative compatibility groups (VCG) and confirmation of deletions in the aflatoxin biosynthesis cluster. Eight atoxigenic isolates were compared for their ability to reduce aflatoxin and CPA contamination in maize kernels in coinoculation tests. The A. flavus population was composed of 32% aflatoxin and CPA producers and 52% CPA producers, and 16% was determined as atoxigenic. All of the aflatoxin producer isolates also produced CPA. Aflatoxin and CPA production was significantly higher in maize kernels than in liquid medium. The 57 nonaflatoxigenic strains formed six VCG, with AM1 and AM5 being the dominant groups, with a frequency of 58 and 35%, respectively. In coinoculation experiments, all of the atoxigenic strains reduced aflatoxin from 54 to 83% and CPA from 60 to 97%. Members of group AM1 showed a greater aflatoxin reduction than members of AM5 (72 versus 66%) but no differences were detected in CPA production. Here, we described for the first time atoxigenic isolates of A. flavus that show promise to be used as BCA in maize crops in Argentina. This innovating biological control approach should be considered, developed further, and used by the maize industry to preserve the quality properties and food safety of maize kernels in Argentina.

Tremorgenic indole metabolites and aflatoxins in sclerotia of Aspergillus flavus: an evolutionary perspective

1982 ◽  
Vol 60 (5) ◽  
pp. 525-528 ◽  
Author(s):  
Donald T. Wicklow ◽  
Richard J. Cole
Keyword(s):  
Aspergillus Flavus ◽  
Culture Medium ◽  
Cyclopiazonic Acid ◽  
Petri Dish ◽  
Potato Dextrose Agar ◽  
Evolutionary Perspective ◽  
Toxic Compounds ◽  
Defense Systems ◽  
Selective Forces ◽  
First Time

Isolates of Aspergillus flavus Link from both cool and warm latitudes were cultured on potato dextrose agar containing yeast extract to identify sclerotia-producing strains. Chloroform–MeOH extracts of sclerotia were analyzed for the presence of aflatoxins and major indole metabolites (e.g., cyclopiazonic acid, aflatrem, and dihydroxyaflavinine). Aflatoxin is reported from sclerotia of A. flavus for the first time. Cyclopiazonic acid was detected primarily in sclerotia of isolates from warmer latitudes. Aflatrem and dihydroxyaflavinine were detected in sclerotia from 85% of the strains examined. These metabolites are associated with the sclerotial stage of the life cycle, because neither were detected in extracts of the culture medium and mycelium of Petri dish cultures from which all the sclerotia were removed. Geographic variation and intrafungal allocation of these toxic compounds in A. flavus are examined from the evolutionary ecologist's perspective of selective forces shaping the chemical defense systems of fungi.

scholarly journals Variation in Competitive Ability Among Isolates of Aspergillus flavus from Different Vegetative Compatibility Groups During Maize Infection

2010 ◽  
Vol 100 (2) ◽  
pp. 150-159 ◽  
Author(s):  
H. L. Mehl ◽  
P. J. Cotty
Keyword(s):  
Aspergillus Flavus ◽  
Competitive Ability ◽  
Aflatoxin Contamination ◽  
Vegetative Compatibility ◽  
Life Strategy ◽  
Nucleotide Polymorphisms ◽  
Vegetative Compatibility Groups ◽  
Kernel Infection ◽  
Aflatoxin B ◽  
Maize Kernels

Aspergillus flavus, the primary causal agent of aflatoxin contamination, includes many genetically diverse vegetative compatibility groups (VCGs). Competitive ability during infection of living maize kernels was quantified for isolates from 38 VCGs. Kernels were inoculated with both a common VCG, CG136, and another VCG; after 7 days (31°C), conidia were washed from kernels, and aflatoxins and DNA were extracted from kernels and conidia separately. CG136-specific single-nucleotide polymorphisms were quantified by pyrosequencing; VCGs co-inoculated with CG136 produced 46 to 85 and 51 to 84% of A. flavus DNA from kernels and conidia, respectively. Co-inoculation with atoxigenic isolates reduced aflatoxin up to 90% and, in some cases, more than predicted by competitive exclusion alone. Conidia contained up to 42 ppm aflatoxin B1, indicating airborne conidia as potentially important sources of environmental exposure. Aflatoxin-producing potential and sporulation were negatively correlated. For some VCGs, sporulation during co-infection was greater than that predicted by kernel infection, suggesting that some VCGs increase dispersal while sacrificing competitive ability during host tissue colonization. The results indicate both life strategy and adaptive differences among A. flavus isolates and provide a basis for selection of biocontrol strains with improved competitive ability, sporulation, and aflatoxin reduction on target hosts.

scholarly journals Association of Mycotoxin and Sclerotia Production with Compatibility Groups in Aspergillus flavus from Peanut in Argentina

Plant Disease ◽  
2002 ◽  
Vol 86 (3) ◽  
pp. 215-219 ◽  
Author(s):  
M. Victoria Novas ◽  
Daniel Cabral
Keyword(s):  
Aspergillus Flavus ◽  
Cyclopiazonic Acid ◽  
Vegetative Compatibility ◽  
Peanut Seed ◽  
Vegetative Compatibility Groups ◽  
Mycotoxin Production ◽  
Comparative Group

Vegetative compatibility (VC) of Aspergillus flavus isolates from peanut seed was studied to evaluate preliminary diversity and its association with mycotoxin production and sclerotia production and number. A. parasiticus isolates also were included as a comparative group. Isolates were divided into five categories based on mycotoxin production combination. Five of the A. flavus isolates were considered atypical because they simultaneously produced aflatoxins B, G, and cyclopiazonic acid (CPA). Vegetative compatibility groups (VCGs) were determined through complementation tests between nitrate-nonutilizing mutants. Sclerotia diameters and the number of sclerotia produced per square centimeter were determined for each isolate. Out of 32 isolates of A. flavus, 25 combined in 13 VCGs, whereas the remaining could not be assigned to any particular group. Each VCG included isolates of the same mycotoxin category, with only one exception. Also, all isolates within the same VCG were characterized by their ability to produce or not produce sclerotia. Isolates between VCGs showed significant differences in number of sclerotia per square centimeter, but differences in sclerotia size were not evident. Atypical isolates simultaneously producing aflatoxins B, G, and CPA formed a single and exclusive VCG.

scholarly journals Identification of Atoxigenic Aspergillus flavus Isolates to Reduce Aflatoxin Contamination of Maize in Kenya

Plant Disease ◽  
2011 ◽  
Vol 95 (2) ◽  
pp. 212-218 ◽  
Author(s):  
C. Probst ◽  
R. Bandyopadhyay ◽  
L. E. Price ◽  
P. J. Cotty
Keyword(s):  
Biological Control ◽  
Aspergillus Flavus ◽  
Aflatoxin Contamination ◽  
Fungal Communities ◽  
Management Tools ◽  
Maize Production ◽  
Vegetative Compatibility Groups ◽  
Potential Value ◽  
Maize Sample ◽  
Maize Kernels

Aspergillus flavus has two morphotypes, the S strain and the L strain, that differ in aflatoxin-producing ability and other characteristics. Fungal communities on maize dominated by the S strain of A. flavus have repeatedly been associated with acute aflatoxin poisonings in Kenya, where management tools to reduce aflatoxin levels in maize are needed urgently. A. flavus isolates (n = 290) originating from maize produced in Kenya and belonging to the L strain morphotype were tested for aflatoxin-producing potential. A total of 96 atoxigenic isolates was identified from four provinces sampled. The 96 atoxigenic isolates were placed into 53 vegetative compatibility groups (VCGs) through complementation of nitrate non-utilizing mutants. Isolates from each of 11 VCGs were obtained from more than one maize sample, isolates from 10 of the VCGs were detected in multiple districts, and isolates of four VCGs were found in multiple provinces. Atoxigenic isolates were tested for potential to reduce aflatoxin concentrations in viable maize kernels that were co-inoculated with highly toxigenic S strain isolates. The 12 most effective isolates reduced aflatoxin levels by >80%. Reductions in aflatoxin levels caused by the most effective Kenyan isolates were comparable with those achieved with a United States isolate (NRRL-21882) used commercially for aflatoxin management. This study identified atoxigenic isolates of A. flavus with potential value for biological control within highly toxic Aspergillus communities associated with maize production in Kenya. These atoxigenic isolates have potential value in mitigating aflatoxin outbreaks in Kenya, and should be evaluated under field conditions.

scholarly journals Mass Spectrometry-Based Network Analysis Reveals New Insights Into the Chemodiversity of 28 Species in Aspergillus section Flavi

2021 ◽  
Vol 2 ◽  
Author(s):  
Xinhui Wang ◽  
Karolina Subko ◽  
Sara Kildgaard ◽  
Jens C. Frisvad ◽  
Thomas O. Larsen
Keyword(s):  
Natural Product ◽  
Filamentous Fungi ◽  
Large Scale ◽  
Cyclopiazonic Acid ◽  
Rapid Identification ◽  
Fungal Species ◽  
Point Of View ◽  
Chemical Diversity ◽  
Molecular Networking ◽  
First Time

Aspergillus section Flavi includes some of the most famous mycotoxin producing filamentous fungi known to mankind. In recent years a number of new species have been included in section Flavi, however these species have been much less studied from a chemical point of view. In this study, we explored one representative strain of a total of 28 fungal species in section Flavi by systematically evaluating the relationship between taxonomy and secondary metabolites with LC-MS/MS analysis for the first time and dereplication through an in-house database and the Global Natural Product Social Molecular Networking (GNPS) platform. This approach allowed rapid identification of two new cyclopiazonic acid producers (A. alliaceus and A. arachidicola) and two new tenuazonic acid producers (A. arachidicola and A. leporis). Moreover, for the first time we report species from section Flavi to produce fumifungin and sphingofungins B-D. Altogether, this study emphasizes that the chemical diversity of species in genus Aspergillus section Flavi is larger than previously recognized, and especially that understudied species are prolific producers of important mycotoxins such as fumi- and sphingofungins not previously reported from this section. Furthermore, our work demonstrates Global Natural Product Social (GNPS) Molecular Networking as a powerful tool for large-scale chemotaxonomic analysis of closely related species in filamentous fungi.

scholarly journals Studies on Aspergillus Flavus Link. Isolated From Maize in Iran

2014 ◽  
Vol 54 (3) ◽  
pp. 218-224 ◽  
Author(s):  
Mahmoud Houshyar-Fard ◽  
Hamid Rouhani ◽  
Mahrokh Falahati-Rastegar ◽  
Esmat Mahdikhani-Moghaddam ◽  
Saeed Malekzadeh-Shafaroudi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Aspergillus Flavus ◽  
Climatic Conditions ◽  
Soil Types ◽  
Nitrate Medium ◽  
Maize Production ◽  
Vegetative Compatibility Groups ◽  
Production Areas ◽  
Maize Kernels

Abstract The Aspergillus flavus population structure from maize kernels was examined. During 2011, samples were collected from two main grain maize production areas in Iran (Fars and Ardebil provinces), shortly before harvest. One-hundred nine A. flavus isolates were recovered on Dichloran Rose Bengal Chloramphenicole (DRBC) agar and Aspergillus flavus/parasiticus medium (AFPA) and grouped into morphotypes and Vegetative Compatibility Groups (VCGs) based on morphological (e.g. sclerotia production), physiological (e.g. aflatoxin-producing ability) and genetic criteria (e.g. heterokaryosis). In general, morphotype and VCG composition were highly dissimilar in both provinces. In total, 43.8% and 44.3% of A. flavus isolates from Ardebil and Fars, respectively, produced sclerotia. Sclerotia producers were identified as A. flavus L and S strain morphotypes in Ardebil (66.7% and 33.3%, respectively) and Fars (29.6% and 70.4%, respectively). Furthermore, 71 isolates (65.1%) were able to produce aflatoxin (Ardebil 40.8%, Fars 59.2%). The aflatoxin values were categorized into four different classes (< 10, 10-100, 100-1,000 and > 1,000 ppb). In total, 51 aflatoxin producing isolates of A. flavus (Ardebil n = 22, Fars n = 29) were assigned into 26 VCGs by complementation of nit auxotrophs on nitrate medium. None of the A. flavus isolates from Ardebil complemented with any isolates from Fars. Genetic diversity of A. flavus isolates was 59.1% and 41.8% for Ardebil and Fars, respectively. The different geographical adaptation and genetic make-up of A. flavus isolates may be due to different climatic conditions, soil types and crop sequences in both maize production areas.

Stereoselective benzylic hydroxylation of ethylbenzene and propylbenzene using the mycelia of Aspergillus flavus MTCC-1783 and MTCC-1884

2012 ◽  
Vol 90 (7) ◽  
pp. 597-599
Author(s):  
Saroj Yadav ◽  
R.S.S. Yadav ◽  
K.D.S. Yadav
Keyword(s):  
Aspergillus Flavus ◽  
Culture Medium ◽  
Potassium Phosphate ◽  
Building Blocks ◽  
Fungal Species ◽  
Potassium Phosphate Buffer ◽  
Liquid Culture Medium ◽  
Benzylic Hydroxylation ◽  
Time Required ◽  
Optically Pure

The aim of this study was to provide syntheses of optically pure (R)-1-phenylethanol and (R)-1-phenylpropanol from ethylbenzene and propylbenzene, respectively, using the fungal mycelia of new fungal species, namely Aspergillus flavus MTCC-1783 and Aspergillus flavus MTCC-1884, as catalysts. The mycelia of A. flavus MTCC- 1783 and A. flavus MTCC-1884 were prepared by growing the fungal strains in liquid culture medium containing ethylmethylketone as the sole carbon source. The mycelia were suspended in potassium phosphate buffer pH 7.0. The suspensions of mycelia were used for the transformations of ethylbenzene and propylbenzene. Ethylbenzene and propylbenzene were converted to (R)-1-phenylethanol and (R)-1-phenylpropanol, in 100% and 99% ee, respectively. The mycelia of A. flavus MTCC-1783 and A. flavus MTCC-1884 can be used for the preparation of (R)-1-phenylethanol and (R)-1-phenylpropanol in 100% and 99% ee, respectively, from ethylbenzene and propylbenzene, respectively. The studies report convenient methods for the syntheses of optically pure isomers, (R)-1-phenylethanol and (R)-1-phenylpropanol, which are important chiral building blocks in the preparations of fine chemicals and pharmaceuticals. The reactions are ecofriendly, occur at 30 °C, and the time required was 24 h.

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

2008 ◽  
Vol 1 (3) ◽  
pp. 333-340 ◽  
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.

scholarly journals Streptomyces roseolus, A Promising Biocontrol Agent Against Aspergillus flavus, the Main Aflatoxin B1 Producer

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 442 ◽  
Author(s):  
Isaura Caceres ◽  
Selma Snini ◽  
Olivier Puel ◽  
Florence Mathieu
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Biocontrol Agent ◽  
Cyclopiazonic Acid ◽  
Over Expression ◽  
Expression Of Genes ◽  
B1 Gene ◽  
Genes Encoding ◽  
Molecular Mechanism Of Action ◽  
Potential Use

Crop contamination by aflatoxin B1 is a current problem in tropical and subtropical regions. In the future, this contamination risk may be expanded to European countries due to climate change. The development of alternative strategies to prevent mycotoxin contamination that further contribute to the substitution of phytopharmaceutical products are thus needed. For this, a promising method resides in the use of biocontrol agents. Several actinobacteria strains have demonstrated to effectively reduce the aflatoxin B1 concentration. Nevertheless, the molecular mechanism of action by which these biological agents reduce the mycotoxin concentration has not been determined. The aim of the present study was to test the potential use of Streptomyces roseolus as a biocontrol agent against aflatoxin B1 contamination. Co-cultures with Aspergillus flavus were conducted, and the molecular fungal response was investigated through analyzing the q-PCR expression of 65 genes encoding relevant fungal functions. Moreover, kojic and cyclopiazonic acid concentrations, as well as morphological fungal changes were also analyzed. The results demonstrated that reduced concentrations of aflatoxin B1 and kojic acid were respectively correlated with the down-regulation of the aflatoxin B1 gene cluster and kojR gene expression. Moreover, a fungal hypersporulated phenotype and a general over-expression of genes involved in fungal development were observed in the co-culture condition.

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