scholarly journals Aspergillus flavus Growth Inhibition and Aflatoxin B1 Decontamination by Streptomyces Isolates and Their Metabolites

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 340
Author(s):  
Ixchel Campos-Avelar ◽  
Alexandre Colas de la Noue ◽  
Noël Durand ◽  
Guillaume Cazals ◽  
Véronique Martinez ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Fungal Growth ◽  
Dual Culture ◽  
Bacterial Cells ◽  
Specific Production ◽  
Penicillium Verrucosum ◽  
Streptomyces Spp ◽  
Residual Toxicity ◽  
Promising Source

Aflatoxin B1 is a potent carcinogen produced by Aspergillus flavus, mainly during grain storage. As pre-harvest methods are insufficient to avoid mycotoxin presence during storage, diverse curative techniques are being investigated for the inhibition of fungal growth and aflatoxin detoxification. Streptomyces spp. represent an alternative as they are a promising source of detoxifying enzymes. Fifty-nine Streptomyces isolates and a Streptomyces griseoviridis strain from the commercial product Mycostop®, evaluated against Penicillium verrucosum and ochratoxin A during previous work, were screened for their ability to inhibit Aspergillus flavus growth and decrease the aflatoxin amount. The activities of bacterial cells and cell-free extracts (CFEs) from liquid cultures were also evaluated. Fifty-eight isolates were able to inhibit fungal growth during dual culture assays, with a maximal reduction going down to 13% of the control. Aflatoxin-specific production was decreased by all isolates to at least 54% of the control. CFEs were less effective in decreasing fungal growth (down to 40% and 55% for unheated and heated CFEs, respectively) and aflatoxin-specific production, with a few CFEs causing an overproduction of mycotoxins. Nearly all Streptomyces isolates were able to degrade AFB1 when growing in solid and liquid media. A total degradation of AFB1 was achieved by Mycostop® on solid medium, as well as an almost complete degradation by IX20 in liquid medium (6% of the control). CFE maximal degradation went down to 37% of the control for isolate IX09. The search for degradation by-products indicated the presence of a few unknown molecules. The evaluation of residual toxicity of the tested isolates by the SOS chromotest indicated a detoxification of at least 68% of AFB1’s genotoxicity.

scholarly journals Licorice, Doum, and Banana Peel Extracts Inhibit Aspergillus flavus Growth and Suppress Metabolic Pathway of Aflatoxin B1 Production

Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1587
Author(s):  
Nesrine H. Youssef ◽  
Sameer H. Qari ◽  
Saleh Matar ◽  
Najwa A. Hamad ◽  
Eldessoky S. Dessoky ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Diethyl Ether ◽  
Plant Extracts ◽  
Aflatoxin B1 ◽  
Fungal Growth ◽  
Dry Weight ◽  
Banana Peel ◽  
Total Phenolic ◽  
Dry Extract ◽  
Promising Source

Three different concentrations of four (ethanol, acetone, methanol, and diethyl ether) extracts of licorice, doum, and banana peel were evaluated for antifungal and antimycotoxigenic efficiency against a maize aflatoxigenic fungus, Aspergillus flavus. Among them, the licorice diethyl ether 75% extract was intensely active, showing the best wet and dry weight inhibition and exhibiting the highest efficacy ratio (91%). Regarding aflatoxin B1 (AFB1) production, all the plant extracts tested were effective against AFB1 production after one month of maize storage, with average efficacy ratios ranging from 74.1% to 97.5%. At the same time, Thiram fungicide exhibited an efficacy ratio of 20.14%. The relative expression levels of three structural genes (aflD, aflP, and aflQ) and two regulatory genes (aflR and aflS) were significantly downregulated when compared to untreated maize grains or Thiram-treated maize grains. The doum diethyl ether 75% peel extract showed the highest total phenolic content (60.48 mg GAE/g dry extract wt.) and antioxidant activity (84.71 μg/mL). GC–MS analysis revealed that dimethoxycinnamic acid, aspartic acid, valproic acid, and linoleic acid might imbue the extracts with antioxidant capacities in relation to fungal growth and aflatoxin biosynthesis. Finally, the results suggest that the three plant extracts can be considered a promising source for developing potentially effective and environmentally safer alternative ways to control aflatoxin formation, thus creating a potentially protective method for grain storage.

scholarly journals Development of an Antifungal and Antimycotoxigenic Device Containing Allyl Isothiocyanate for Silo Fumigation

Toxins ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 137 ◽  
Author(s):  
Juan Quiles ◽  
Tiago Nazareth ◽  
Carlos Luz ◽  
Fernando Luciano ◽  
Jordi Mañes ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Ochratoxin A ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Fungal Growth ◽  
Allyl Isothiocyanate ◽  
Bioactive Compound ◽  
Previous Trial ◽  
Control Test ◽  
Penicillium Verrucosum

The aims of this study were to evaluate the antifungal activity of the bioactive compound allyl isothiocyanate (AITC) against Aspergillus flavus (8111 ISPA) aflatoxins (AFs) producer and Penicillium verrucosum (D-01847 VTT) ochratoxin A (OTA) producer on corn, barley, and wheat. The experiments were carried out initially in a simulated silo system for laboratory scale composed of glass jars (1 L). Barley and wheat were contaminated with P. verrucosum and corn with A. flavus. The cereals were treated with a hydroxyethylcellulose gel disk to which 500 µL/L of AITC were added; the silo system was closed and incubated for 30 days at 21 °C. After that, simulated silos of 100 L capacity were used. Barley, wheat, and corn were contaminated under the same conditions as the previous trial and treated with disks with 5 mL of AITC, closed and incubated for 90 days at 21 °C. In both cases, the control test did not receive any antifungal treatment. The growth of the inoculated fungi and the reduction in the formation of AFs and OTA were determined. In the lab scale silo system, complete inhibition of fungal growth at 30 days has been observed. In corn, the reduction of aflatoxin B1 (AFB1) was 98.5%. In the 100 L plastic drums, a significant reduction in the growth of A. flavus was observed, as well as the OTA formation in wheat (99.5%) and barley (92.0%).

scholarly journals Minimizing Ochratoxin A Contamination through the Use of Actinobacteria and Their Active Molecules

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 296
Author(s):  
Ixchel Campos-Avelar ◽  
Alexandre Colas de la Noue ◽  
Noel Durand ◽  
Blandine Fay ◽  
Véronique Martinez ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Fungal Pathogens ◽  
Fungal Growth ◽  
Dual Culture ◽  
Specific Production ◽  
Penicillium Verrucosum ◽  
Subsequent Degradation ◽  
Food Commodities ◽  
Detoxification Mechanisms

Ochratoxin A (OTA) is a secondary metabolite produced by fungal pathogens such as Penicillium verrucosum, which develops in food commodities during storage such as cereals, grapes, and coffee. It represents public health concerns due to its genotoxicity, carcinogenicity, and teratogenicity. The objective of this study was to evaluate the ability of actinobacteria and their metabolites to degrade OTA and/or to decrease its production. Sixty strains of actinobacteria were tested for their ability to prevent OTA formation by in vitro dual culture assays or with cell free extracts (CFEs). In dual culture, 17 strains strongly inhibited fungal growth, although it was generally associated with an increase in OTA specific production. Seventeen strains inhibited OTA specific production up to 4% of the control. Eleven actinobacteria CFEs reduced OTA specific production up to 62% of the control, while no substantial growth inhibition was observed except for two strains up to 72% of the control. Thirty-three strains were able to degrade OTA almost completely in liquid medium whereas only five were able to decrease it on solid medium, and two of them reduced OTA to an undetectable amount. Our results suggest that OTA decrease could be related to different strategies of degradation/metabolization by actinobacteria, through enzyme activities and secretion of secondary metabolites interfering with the OTA biosynthetic pathway. CFEs appeared to be ineffective at degrading OTA, raising interesting questions about the detoxification mechanisms. Common degradation by-products (e.g., OTα or L-β-phenylalanine) were searched by HPLC-MS/MS, however, none of them were found, which implies a different mechanism of detoxification and/or a subsequent degradation into unknown products.

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.

Lysis and biological control of Aspergillus niger by Bacillus subtilis AF 1

1996 ◽  
Vol 42 (6) ◽  
pp. 533-538 ◽  
Author(s):  
A. R. Podile ◽  
A. P. Prakash
Keyword(s):  
Biological Control ◽  
Bacillus Subtilis ◽  
Aspergillus Niger ◽  
Fungal Growth ◽  
Dry Weight ◽  
Crown Rot ◽  
Fungal Mycelium ◽  
Infested Soil ◽  
Dual Culture ◽  
Bacterial Cells

A biocontrol rhizobacterial strain of Bacillus subtilis AF 1 grown for 6 h was coinoculated with Aspergillus niger at different time intervals and microscopic observations revealed adherence of bacterial cells to the fungal mycelium. Bacterial cells multiplied in situ and colonized the mycelial surface. Growth of AF 1 resulted in damage to the cell wall, followed by lysis. AF 1 inoculation into media containing A. niger at 0, 6, and 12 h suppressed >90% fungal growth, while in 18- and 24-h cultures fungal growth inhibition was 70 and 56%, respectively, in terms of dry weight. In dual culture the fungal growth was not accompanied by formation of spores. The mycelial preparation of A. niger as principal carbon source supported the growth of B. subtilis, as much as chitin. Extracellular protein precipitate from B. subtilis culture filtrate had a significant growth-retarding effect on A. niger. Groundnut seeds bacterized with B. subtilis showed a reduced incidence of crown rot in A. niger infested soil, suggesting a possible role of B. subtilis in biological control of A. niger.Key words: mycolytic bacteria, Bacillus subtilis, Aspergillus niger, biological control.

Fungal Growth and Aflatoxin Production on Apiarian Substrates

1977 ◽  
Vol 60 (1) ◽  
pp. 96-99
Author(s):  
Jo Ann L Hilldrup ◽  
Thomas Eadie ◽  
Gerald C Llewellyn
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Brood Comb

Abstract Unprocessed honey, Lilium longiflorium pollen, brood comb, whole larvae, and whole bees were inoculated with Aspergillus flavus NRRL 3251, A. flavus ATCC 15548, and A. parasiticus NRRL 2999. The fungi grew, sporulated, and produced various amounts of aflatoxin on all substrates except the unprocessed honey. The largest quantity of aflatoxin B1 was produced on whole larvae supporting A. flavus NRRL 3251 growth. A. parasiticus NRRL 2999 growing on whole larvae produced the most aflatoxin G1. Aflatoxins B2 and G2 were seldom detected. Apiarian substrates with the exception of honey seem capable of supporting fungal growth and resultant aflatoxin production.

scholarly journals Chemical Composition and Antifungal Activity of Ocimum basilicum L. Essential Oil

2015 ◽  
Vol 3 (3) ◽  
pp. 374-379 ◽  
Author(s):  
Neveen Helmy Abou El-Soud ◽  
Mohamed Deabes ◽  
Lamia Abou El-Kassem ◽  
Mona Khalil
Keyword(s):  
Chemical Composition ◽  
Antifungal Activity ◽  
Essential Oil ◽  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Fungal Growth ◽  
Ocimum Basilicum ◽  
Growth Media ◽  
Oil Concentration

BACKGROUND: The leaves of Ocimum basilicum L. (basil) are used in traditional cuisine as spices; its essential oil has found a wide application in perfumery, dental products as well as antifungal agents.AIM: To assess the chemical composition as well as the in vitro antifungal activity of O. basilicum L. essential oil against Aspergillus flavus fungal growth and aflatoxin B1 production.MATERIAL AND METHODS: The essential oil of O. basilicum was obtained by hydrodistillation and analysed using gas chromatography (GC) and GC coupled with mass spectrometry (GC/MS). The essential oil was tested for its effects on Aspergillus flavus (A. flavus) mycelial growth and aflatoxin B1 production in Yeast Extract Sucrose (YES) growth media. Aflatoxin B1 production was determined by high performance liquid chromatography (HPLC).RESULTS: Nineteen compounds, representing 96.7% of the total oil were identified. The main components were as follows: linalool (48.4%), 1,8-cineol (12.2%), eugenol (6.6%), methyl cinnamate (6.2%), α-cubebene (5.7%), caryophyllene (2.5%), β-ocimene (2.1%) and α-farnesene (2.0%).The tested oil showed significant antifungal activity that was dependent on the used oil concentration. The complete inhibition of A. flavus growth was observed at 1000 ppm oil concentration, while marked inhibition of aflatoxin B1 production was observed at all oil concentrations tested (500, 750 and 1000 ppm).CONCLUSION: These results confirm the antifungal activities of O. basilicum L. oil and its potential use to cure mycotic infections and act as pharmaceutical preservative against A. flavus growth and aflatoxin B1 production.

scholarly journals Maize Milling and Modifying Atmospheric Conditions Limit Formation of Aflatoxin B1 by Aspergillus Flavus

2021 ◽  
Vol 12 (2) ◽  
pp. 16
Author(s):  
Benigni Alfred Temba ◽  
Gaymary George Bakari
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Fungal Growth ◽  
Health Concern ◽  
Atmospheric Conditions ◽  
Physical Status ◽  
The World ◽  
Baseline Information ◽  
Petri Dishes ◽  
Maize Kernels

Occurrence of mycotoxins in foods poses a serious health concern all over the world. Aflatoxin B1 (AFB1) is the most toxic, with widest occurrence in various foods, but mainly in cereals and nuts and its accumulation depends on substrate and environmental factors. This study investigated the how physical status (milling) of maize kernels and atmospheric conditions (aeration, moisture and temperature) affect production of aflatoxin B1 by Aspergillus flavus (ATCC 28862). Intact kernels and flour were incubated for up to 20 days in open and partially sealed petri dishes under controlled temperatures of 25 ºC, 30 ºC and 37 ºC and initial moisture contents of 27%, 22%, 18%, 15% and 12%. It was found that on average, significantly higher (p < 0.05) aflatoxin B1 level was accumulated in intact kernels (145.7 µg/kg) as compared to milled kernels (2.2 µg/kg). Also, none of the samples incubated under partially sealed conditions, compared to up to 100% of the samples incubated in open atmosphere had detectable levels of aflatoxin B1 after 20 days. Fungal growth was not affected by milling or aeration, but sporulation was low at 37 ºC and high at 25 ºC and 30 ºC. The findings of this study provide baseline information on how conditions can be modified to control postharvest accumulation of aflatoxin B1 in cereals.

scholarly journals Antifungal and Antiaflatoxigenic Activities of 1,8-Cineole and t-Cinnamaldehyde on Aspergillus flavus

2018 ◽  
Vol 8 (9) ◽  
pp. 1655 ◽  
Author(s):  
Hyeong-Mi Kim ◽  
Hyunwoo Kwon ◽  
Kyeongsoon Kim ◽  
Sung-Eun Lee
Keyword(s):  
Propionic Acid ◽  
Aspergillus Flavus ◽  
Growth Medium ◽  
Aflatoxin B1 ◽  
Mode Of Action ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Inhibitory Effects ◽  
Aflatoxin B2

Aspergillus flavus and A. parsiticus produce aflatoxins that are highly toxic to mammals and birds. In this study, the inhibitory effects of 1,8-cineole and t-cinnamaldehyde were examined on the growth of Aspergillus flavus ATCC 22546 and aflatoxin production. 1,8-Cineole showed 50% inhibition of fungal growth at a concentration of 250 ppm, while t-cinnamaldehyde almost completely inhibited fungal growth at a concentration of 50 ppm. Furthermore, no fungal growth was observed when the growth medium was treated with 100 ppm t-cinnamaldehyde. 1,8-Cineole also exhibited 50% inhibition on the production of aflatoxin B1 and aflatoxin B2 at a concentration of 100 ppm, while the addition of 100 ppm t-cinnamaldehyde completely inhibited aflatoxin production. These antiaflatoxigenic activities were related to a dramatic downregulation of the expression of aflE and aflL by 1,8-cineole, but the mode of action for t-cinnamaldehyde was unclear. Collectively, our results suggest that both of the compounds are promising alternatives to the currently used disinfectant, propionic acid, for food and feedstuff preservation.

Inhibition of Aspergillus flavus growth and aflatoxin B1 production by natamycin

2021 ◽  
pp. 1-16
Author(s):  
P. Chang ◽  
B. Tai ◽  
M. Zheng ◽  
Q. Yang ◽  
F. Xing
Keyword(s):  
Aspergillus Flavus ◽  
Animal Health ◽  
Fungal Growth ◽  
Outer Wall ◽  
Aflatoxin Production ◽  
Ergosterol Biosynthesis ◽  
Dependent Manner ◽  
Conidia Germination ◽  
Streptomyces Spp ◽  
Inhibitory Mechanisms

Aspergillus flavus causes huge crop losses, reduces crop quality and has adverse effects on human and animal health. A large amount of food contaminated with aflatoxin can greatly increase the risk of liver cancer. Therefore, prevention and control of aflatoxin production have aroused attention of research in various countries. Natamycin extracted from Streptomyces spp. has been widely used in production practice due to its good specificity and safety. Here, we found that natamycin could significantly inhibit fungal growth, conidia germination, ergosterol and AFB1 production by A. flavus in a dose-dependent manner. Scanning electron microscope analysis indicated that the number of conidia was decreased, the outer wall of conidia was destroyed, and the mycelia were shrivelled and tangled by natamycin. RNA-Seq data indicated that natamycin inhibited fungal growth and conidia development of A. flavus by significantly down-regulating some genes involved in ergosterol biosynthesis, such as Erg13, HMG1 and HMG2. It inhibited conidia germination by significantly down-regulating some genes related to conidia development, such as FluG and VosA. After natamycin exposure, the decreased ratio of aflS/aflR caused by the down-regulation of all the structural genes, which subsequently resulted in the suppression of AFB1 production. In conclusion, this study served to reveal the inhibitory mechanisms of natamycin on fungal growth and AFB1 biosynthesis in A. flavus and to provide solid evidence for its application in controlling AFB1 contamination.

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