Co-occurrence of aflatoxin B1 and cyclopiazonic acid in sour lime (Citrus aurantifolia Swingle) during post-harvest pathogenesis by Aspergillus flavus

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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Abiotic factors and their interactions influence on the co-production of aflatoxin B1 and cyclopiazonic acid by Aspergillus flavus isolated from corn

Food Microbiology ◽

10.1016/j.fm.2013.07.012 ◽

2014 ◽

Vol 38 ◽

pp. 276-283 ◽

Cited By ~ 27

Author(s):

Andrea Astoreca ◽

Graciela Vaamonde ◽

Ana Dalcero ◽

Sonia Marin ◽

Antonio Ramos

Keyword(s):

Aspergillus Flavus ◽

Aflatoxin B1 ◽

Abiotic Factors ◽

Cyclopiazonic Acid

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

Toxins ◽

10.3390/toxins13060391 ◽

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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Impacts of Climate Change Interacting Abiotic Factors on Growth, aflD and aflR Gene Expression and Aflatoxin B1 Production by Aspergillus flavus Strains In Vitro and on Pistachio Nuts

Toxins ◽

10.3390/toxins13060385 ◽

2021 ◽

Vol 13 (6) ◽

pp. 385

Author(s):

Alaa Baazeem ◽

Alicia Rodriguez ◽

Angel Medina ◽

Naresh Magan

Keyword(s):

Climate Change ◽

Gene Expression ◽

Water Stress ◽

Aspergillus Flavus ◽

Aflatoxin B1 ◽

Abiotic Factors ◽

Pistachio Nuts ◽

Significant Difference ◽

Spoilage Fungi

Pistachio nuts are an important economic tree nut crop which is used directly or processed for many food-related activities. They can become colonized by mycotoxigenic spoilage fungi, especially Aspergillus flavus, mainly resulting in contamination with aflatoxins (AFs), especially aflatoxin B1 (AFB1). The prevailing climate in which these crops are grown changes as temperature and atmospheric CO2 levels increase, and episodes of extreme wet/dry cycles occur due to human industrial activity. The objectives of this study were to evaluate the effect of interacting Climate Change (CC)-related abiotic factors of temperature (35 vs. 37 °C), CO2 (400 vs. 1000 ppm), and water stress (0.98–0.93 water activity, aw) on (a) growth (b) aflD and aflR biosynthetic gene expression and (c) AFB1 production by two strains A. flavus (AB3, AB10) in vitro on milled pistachio-based media and when colonizing layers of shelled raw pistachio nuts. The A. flavus strains were resilient in terms of growth on pistachio-based media and the colonisation of pistachio nuts with no significant difference when exposed to the interacting three-way climate-related abiotic factors. However, in vitro studies showed that AFB1 production was significantly stimulated (p < 0.05), especially when exposed to 1000 ppm CO2 at 0.98–0.95 aw and 35 °C, and sometimes in the 37 °C treatment group at 0.98 aw. The relative expression of the structural aflD gene involved in AFB1 biosynthesis was decreased or only slightly increased, relative to the control conditions at elevated CO, regardless of the aw level examined. For the regulatory aflR gene expression, there was a significant (p < 0.05) increase in 1000 ppm CO2 and 37 °C for both strains, especially at 0.95 aw. The in situ colonization of pistachio nuts resulted in a significant (p < 0.05) stimulation of AFB1 production at 35 °C and 1000 ppm CO2 for both strains, especially at 0.98 aw. At 37 °C, AFB1 production was either decreased, in strain AB3, or remained similar, as in strain AB10, when exposed to 1000 ppm CO2. This suggests that CC factors may have a differential effect, depending on the interacting conditions of temperature, exposure to CO2 and the level of water stress on AFB1 production.

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Production of aflatoxins and aflatoxicols by Aspergillus flavus and Aspergillus parasiticus and metabolism of aflatoxin B1 by aflatoxin-non-producing Aspergillus flavus.

Eisei kagaku ◽

10.1248/jhs1956.37.107 ◽

1991 ◽

Vol 37 (2) ◽

pp. 107-116 ◽

Cited By ~ 6

Author(s):

MITSUO NAKAZATO ◽

SATOSHI MOROZUMI ◽

KAZUO SAITO ◽

KENJI FUJINUMA ◽

TAICHIRO NISHIMA ◽

...

Keyword(s):

Aspergillus Flavus ◽

Aflatoxin B1 ◽

Aspergillus Parasiticus

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EVALUATION OF SUSCEPTIBILITY OF PISTACHIO CULTIVARS TO AFLATOXIGENIC ASPERGILLUS FLAVUS AND AFLATOXIN B1 PRODUCTION

Acta Horticulturae ◽

10.17660/actahortic.2006.726.113 ◽

2006 ◽

pp. 655-658 ◽

Cited By ~ 3

Author(s):

M.M. Moghaddam ◽

E.M. Goltapeh ◽

H. Hokmabadi ◽

M. Haghdel ◽

A.M. Mortazavi

Keyword(s):

Aspergillus Flavus ◽

Aflatoxin B1

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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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