Impact of bacterial biocontrol agents on aflatoxin biosynthetic genes, aflD and aflR expression, and phenotypic aflatoxin B1 production by Aspergillus flavus under different environmental and nutritional regimes

Al-Saad, Labeed A.; Al-Badran, Adnan Issa; Al-Jumayli, Sami A.; Magan, Naresh; Rodríguez, Alicia

doi:10.1016/j.ijfoodmicro.2015.10.016

Cited by 36 publications

(20 citation statements)

References 30 publications

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“…The expression of aflR and aflQ of the aflatoxins biosynthesis cluster was analyzed Sweeney, Pamies, & Dobson (2000) using reverse transcription PCR, while Mayer, Bagnara, Farber, & Geisen (2003) examined the expression of aflD and the aflatoxin yield in wheat. Recently, Al-Saad, Al-Badran, Al-Jumayli, Magan, & Rodriguez (2016) reported the impact of bacterial biocontrol agents on aflD and aflR expression and aflatoxin B 1 production when A. flavus was grown under different environmental conditions and with various nutritional media. The expression of secondary metabolite biosynthesis cluster genes in A. flavus, A. parasiticus, and Aspergillus oryzae has also been compared (Ehrlich & Mack, 2014).…”

Section: Introductionmentioning

confidence: 99%

Functional analyses of the versicolorin B synthase gene in Aspergillus flavus

et al. 2017

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Aflatoxin is a toxic, carcinogenic mycotoxin primarily produced by Aspergillus parasiticus and Aspergillus flavus. Previous studies have predicted the existence of more than 20 genes in the gene cluster involved in aflatoxin biosynthesis. Among these genes, aflK encodes versicolorin B synthase, which converts versiconal to versicolorin B. Past research has investigated aflK in A. parasiticus, but few studies have characterized aflK in the animal, plant, and human pathogen A. flavus. To understand the potential role of aflK in A. flavus, its function was investigated here for the first time using gene replacement and gene complementation strategies. The aflK deletion‐mutant ΔaflK exhibited a significant decrease in sclerotial production and aflatoxin biosynthesis compared with wild‐type and the complementation strain ΔaflK::aflK. ΔaflK did not affect the ability of A. flavus to infect seeds, but downregulated aflatoxin production after seed infection. This is the first report of a relationship between aflK and sclerotial production in A. flavus, and our findings indicate that aflK regulates aflatoxin formation.

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Section: Introductionmentioning

confidence: 99%

Functional analyses of the versicolorin B synthase gene in Aspergillus flavus

et al. 2017

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“…The changes in biocontrol potential under different environmental conditions has been seen previously both for fungal and bacterial biocontrol agents (Mohale et al, 2013;Al-Saad et al, 2016;Cary et al, 2016). The findings in the present work differ from those of Mohale et al (2013) who found that irrespective of temperature, at higher  (-1.4 MPa; -5.6 MPa) atoxigenic biocontrol strains and aflatoxigenic Aspergillus flavus strains co-existed.…”

Section: Discussionmentioning

confidence: 56%

“…Recent work by Cary et al (2016) suggests that under marginal conditions for the activity of bacterial biocontrol inoculants they can stimulate fungal pathogen growth. Similarly, Al-Saad et al (2016) found that while some bacterial antagonists effectively controlled growth of A. flavus, under water stress aflatoxin B1 production was 9 stimulated. Thus, environmental fluxes may influence the interaction between the antagonist and fungal pathogen and that different species might adopt different mechanisms of action which in turn can contribute to the different exclusion competence of individual species or strains.…”

Section: Discussionmentioning

confidence: 92%

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Relationship between environmental conditions, carbon utilisation patterns and Niche Overlap Indices of the mycotoxigenic species Fusarium verticillioides and the biocontrol agent Clonostachys rosea

2016

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Recently, it was shown that a strain of the fungal antagonist Clonostachys rosea 016 was able to inhibit fumonisin B1 mycotoxin production by Fusarium verticillioides FV1 when using different ratios of spores of each species in vitro. The objectives of the present work were therefore to: (a) compare the nutritional utilisation patterns and rates of uptake of key Csources in maize by the antagonist C. rosea 016 and that by the pathogen F. verticillioides FV1; (b) examine their Niche Overlap Indices (NOI) under different interacting environmental conditions; and (c) evaluate whether the rate of utilisation of key maize Csources influenced the competitiveness of either species using the Bioscreen®. It was found that water potential () temperature interactions had significant impacts on C-source utilisation patterns by C. rosea 016 and the pathogen. The NOIs, based on the utilisation of the C-sources by each strain divided by those utilised in common, showed that the antagonist and the pathogen occupied similar niches at -0.70 MPa +30°C and -2.8 MPa +25°C. Under the other conditions tested, they appeared to occupy separate niches suggesting niche exclusion. Temporal C-source utilisation patterns were then compared under different   temperature treatments. This showed that the dominant maize-based C-sources utilised by the pathogen and the antagonist were different. The pathogen F. verticillioides FV1 utilised carbohydrates rapidly followed by amino acids and then one fatty acid, palmitic acid. The antagonist C. rosea 016 utilised both carbohydrates and amino acids at a similar rate but more slowly than the pathogen. There were also differences in the utilisation of some individual amino acids and carbohydrates which might explain the occupation of different niches under some interacting environmental conditions. These findings are discussed in the context of why some competitors are able to inhibit mycotoxin production while others cannot.

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“…The combined effects of incubation time, temperature, water activity (aw), and CO 2 on the growth of and aflatoxin production by A. flavus were studied [119]. Nutritional sources were also demonstrated to have a significant influence on fungal growth and mycotoxin production [120,121]. Additionally, the expression of aflatoxin-synthesis related genes were demonstrated to be highly in relation to changes in water activity and temperature levels [122][123][124].…”

Section: Factors Influencing Antifungal Activitiesmentioning

confidence: 99%

Control of Aflatoxigenic Molds by Antagonistic Microorganisms: Inhibitory Behaviors, Bioactive Compounds, Related Mechanisms, and Influencing Factors

Ren

Zhang

et al. 2020

Toxins

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Aflatoxin contamination has been causing great concern worldwide due to the major economic impact on crop production and their toxicological effects to human and animals. Contamination can occur in the field, during transportation, and also in storage. Post-harvest contamination usually derives from the pre-harvest infection of aflatoxigenic molds, especially aflatoxin-producing Aspergilli such as Aspergillus flavus and A. parasiticus. Many strategies preventing aflatoxigenic molds from entering food and feed chains have been reported, among which biological control is becoming one of the most praised strategies. The objective of this article is to review the biocontrol strategy for inhibiting the growth of and aflatoxin production by aflatoxigenic fungi. This review focuses on comparing inhibitory behaviors of different antagonistic microorganisms including various bacteria, fungi and yeasts. We also reviewed the bioactive compounds produced by microorganisms and the mechanisms leading to inhibition. The key factors influencing antifungal activities of antagonists are also discussed in this review.

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Impact of bacterial biocontrol agents on aflatoxin biosynthetic genes, aflD and aflR expression, and phenotypic aflatoxin B1 production by Aspergillus flavus under different environmental and nutritional regimes

Cited by 36 publications

References 30 publications

Functional analyses of the versicolorin B synthase gene in Aspergillus flavus

Functional analyses of the versicolorin B synthase gene in Aspergillus flavus

Relationship between environmental conditions, carbon utilisation patterns and Niche Overlap Indices of the mycotoxigenic species Fusarium verticillioides and the biocontrol agent Clonostachys rosea

Control of Aflatoxigenic Molds by Antagonistic Microorganisms: Inhibitory Behaviors, Bioactive Compounds, Related Mechanisms, and Influencing Factors

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