Effect of Various Compounds Blocking the Colony Pigmentation on the Aflatoxin B1 Production by Aspergillus flavus

Abstract

Aflatoxins and melanins are the products of a polyketide biosynthesis. In this study, the search of potential inhibitors of the aflatoxin B1 (AFB1) biosynthesis was performed among compounds blocking the pigmentation in fungi. Four compounds—three natural (thymol, 3-hydroxybenzaldehyde, compactin) and one synthetic (fluconazole)—were examined for their ability to block the pigmentation and AFB1 production in Aspergillus flavus. All compounds inhibited the mycelium pigmentation of a fungus growing on solid medium. At the same time, thymol, fluconazole, and 3-hydroxybenzaldehyde stimulated AFB1 accumulation in culture broth of A. flavus under submerged fermentation, whereas the addition of 2.5 μg/mL of compactin resulted in a 50× reduction in AFB1 production. Moreover, compactin also suppressed the sporulation of A. flavus on solid medium. In vivo treatment of corn and wheat grain with compactin (50 μg/g of grain) reduced the level of AFB1 accumulation 14 and 15 times, respectively. Further prospects of the compactin study as potential AFB1 inhibitor are discussed.

Assessment of the Sensitivity of Some Plant Pathogenic Fungi to 6-Demethylmevinolin, a Putative Natural Sensitizer Able to Help Overcoming the Fungicide Resistance of Plant Pathogens

“…These compounds cause mycotoxicoses in animals and are carcinogens and/or allergens for humans, while their producers are among nosocomial infections that are especially dangerous for immunodeficient patients. Earlier we showed that 6-DMM suppressed the biosynthesis of a polyketide aflatoxin B1 in a toxigenic Aspergillus flavus [45]. In this regard, there is a suggestion that the antifungal effect of 6-DMM may be accompanied by the inhibition of the biosynthesis of toxins in other toxigenic fungi.…”

Effective Zearalenone Degradation in Model Solutions and Infected Wheat Grain Using a Novel Heterologous Lactonohydrolase Secreted by Recombinant Penicillium canescens

“…However, further investigations are necessary to confirm the PR-ZHD promise for the application on ZEN-polluted forage wheat with the purpose of simultaneous decontamination and improving the availability of feed nutritional components. Another possible way to provide a highly effective biological protection of agricultural feedstock from contamination is a combination of mycotoxin-degrading enzyme preparations and the natural inhibitors of the toxigenesis [50]. Such preparations might be used for providing an additional feed decontamination in those cases when an inhibitor incompletely suppresses the biosynthesis of mycotoxins.…”

Functional characterization of the sterigmatocystin secondary metabolite gene cluster in the filamentous fungus Podospora anserina: involvement in oxidative stress response, sexual development, pigmentation and interspecific competitions

“…This implies that ST and melanin biosynthesis pathways could be linked, either directly or indirectly. Referring to the structural similarities between the first stable intermediate of melanin biosynthesis and AF biosynthesis in Aspergillus species, some researchers proposed that AF and melanin biosynthetic pathway share common initial stages, later the polyketide biosynthetic chain may branch toward different pathways resulting in the production of either AF or melanin (Brown and Salvo, 1994;Dzhavakhiya et al, 2016).…”