Phylogenetic diversity and prevalence of mycoflora in ready-to-eat supermarket and roadside-vended peanuts

Little is known of the mycobiota present in ready-to-eat peanuts consumed in Southern Africa. Knowledge of the mycobiota and aflatoxigenic species can elucidate potential health risks associated with consumption of ready-to-eat peanuts sold by supermarkets and roadside vendors. We investigated the culturable mycobiota diversity in supermarket and roadside-vended peanuts as well as the presence of five aflatoxin biosynthesis pathway–related genes (<i>aflR, aflJ, aflM, aflD</i>, and <i>aflP</i>) in 15 suspected aflatoxigenic isolates, with a focus on Mafikeng, South Africa. Mean colony-forming unit (CFU) counts of 288.7 and 619.7 CFU/g were observed in supermarket and roadside-vended peanuts, respectively. A total of 145 fungal isolates comprising 26 distinct taxa (based on 97% internal transcribed spacer region [ITS1-5.8S-ITS2] sequence similarity) were obtained, including strains representing <i>Aspergillus, Acremonium, Alternaria, Bipolaris, Chaetomium, Ectophoma, Epicoccum, Hamigera, Leancillium, Monascus, Penicillium, Periconia, Talaromyces</i>, and <i>Trichoderma</i>. Phylogenetic analyses of concatenated sequences of the ITS1-5.8S-ITS2, β-tubulin, and calmodulin genes delineated the species of As<i>pergillus</i>, which included <i>A. flavus, A. fumigatus, A. hiratsukae, A. niger</i>, and <i>A. parasiticus</i>. Higher species richness was obtained from supermarket peanuts compared with roadside-vended peanuts, with eight species common to both sources. Across supermarket or roadside-vended peanuts, <i>A. fumigatus, A. niger</i>, and <i>A. flavus</i> were prevalent (&gt;40% incidence). In contrast, strains related to or representing <i>Ectophoma multirostata, Aspergillus hiratsukae, Bipolaris zeae, Chaetomium bostrychodes, Epicoccum nigrum, Hamigera paravellanea, Lecanicillium aphanocladii, Monascus ruber, Periconia macrospinosa, Periconia lateralis, Talaromyces funiculosus, Talaromyces minioluteus, Talaromyces wortmannii, Talaromyces</i> spp., and <i>Trichoderma</i> sp. were detected in either supermarket or roadside-vended peanuts. Among the five aflatoxin biosynthesis pathway–related genes, <i>aflD</i> and <i>aflM</i> were more prevalent (87%) and <i>aflR</i> was the least prevalent (40%). Findings suggest that roasted peanuts meant for human consumption and sold at supermarkets and by roadside vendors are contaminated with potential toxin-producing fungi. Hence, proper processing and packaging of peanuts before vending is recommended.