Phenotypic Differentiation of Two Morphologically Similar Aflatoxin-Producing Fungi from West Africa

Abstract

Aflatoxins (AF) are hepatocarcinogenic metabolites produced by several Aspergillus species. Crop infection by these species results in aflatoxin contamination of cereals, nuts, and spices. Etiology of aflatoxin contamination is complicated by mixed infections of multiple species with similar morphology and aflatoxin profiles. The current study investigates variation in aflatoxin production between two morphologically similar species that co-exist in West Africa, A. aflatoxiformans and A. minisclerotigenes. Consistent distinctions in aflatoxin production during liquid fermentation were discovered between these species. The two species produced similar concentrations of AFB1 in defined media with either urea or ammonium as the sole nitrogen source. However, production of both AFB1 and AFG1 were inhibited (p < 0.001) for A. aflatoxiformans in a yeast extract medium with sucrose. Although production of AFG1 by both species was similar in urea, A. minisclerotigenes produced greater concentrations of AFG1 in ammonium (p = 0.039). Based on these differences, a reliable and convenient assay for differentiating the two species was designed. This assay will be useful for identifying specific etiologic agents of aflatoxin contamination episodes in West Africa and other regions where the two species are sympatric, especially when phylogenetic analyses based on multiple gene segments are not practical.

Aflatoxin contamination of maize and groundnut in Burundi: Distribution of contamination, identification of causal agents and potential biocontrol genotypes of Aspergillus flavus

“…A. flavus is subdivided in two morphotypes, L and S, which differ in genetic, physiological, and toxigenic characteristics ( Cotty, 1989 ). Across SSA there are many types of aflatoxigenic fungi, several of them not formally described, that resemble the S-morphotype but that are not closely related ( Frisvad et al, 2019 ; Singh et al, 2020 ). Some of those types of fungi produce B and G aflatoxins ( Cotty and Cardwell, 1999 ).…”

Single-Molecule Real-Time Sequencing to Explore the Mycobiome Diversity in Malt

“… Aspergillus minisclerotigenes , Aspergillus sclerotiorum , Fusarium poae , Candida tropicalis , and Trichothecium roseum were the main toxigenic and pathogenic fungi detected in the malt samples, three of which (samples M5, CM8, and CM9) were ZEN positive ( Table 1 ). Notably, Aspergillus minisclerotigenes can produce aflatoxins, while some Aspergillus sclerotiorum strains can generate OTA ( 38 , 39 ), indicating that the presence of toxigenic fungi in the malt did not necessarily result in the production and accumulation of mycotoxins. However, the absence of visible molds does not guarantee the absence of mycotoxins in food.…”

Atoxigenic-based technology for biocontrol of aflatoxin in maize and groundnuts for Tanzania

“…The S morphotype of A. flavus is not very common in African countries, but fungi belonging to diverse species resembling this morphotype (e.g. Aspergillus aflatoxiformans, Aspergillus minisclerotigenes) are relatively common across Africa (Frisvad et al, 2019;Singh et al, 2020). Some of these species produce both B and G aflatoxins.…”