Detecção molecular de fungos toxigénicos em produtos agrícolas em Moçambique

Abstract

Mycotoxins are secondary metabolites produced mainly by species of Aspergillus, Penicillium, and Fusarium. Aflatoxin, for example, represents a serious public health problem due to its mutagenic, immunosuppressive, and hepatocarcinogenic properties. African countries like Mozambique raise greater concern due to the lack of monitoring programs for agricultural crop contamination, poor agricultural practices in harvesting, storage, processing, and transportation, associated with the region's humid tropical climate. Currently, the country has conventional detection techniques that are not very precise or sensitive, which contributes to the entry of mycotoxins into the food chain. This study investigated the application of molecular techniques for the early detection of toxigenic fungi in agricultural products from different agroecological regions of Mozambique.

Twenty-five samples (13 of maize and 12 of peanut) were collected from the Southern (Boane, Marracuene, Boquisso and Manhiça), Central (Manica) and Northern (Murrupula and Pemba) regions of the country. Fungal identification was initially performed by macroscopy and microscopy followed by molecular confirmation with the ITS1 and ITS4 primers. The presence of key genes of the aflatoxin biosynthetic pathway (aflR, nor-1, omtB, omt-1 and ordA) was evaluated by PCR to determine the aflatoxigenic potential.

Morphological analysis revealed a predominance of Aspergillus (84%), followed by Penicillium (56%) and Fusarium (32%). PCR ITS1/ITS4 amplification confirmed the morphological results in 100% of the samples with fragments of approximately 600 bp. Research using the Primer BLAST tool confirmed the association of the sizes of the products obtained with the main toxigenic species, especially the aflatoxigenic A. flavus and A. parasiticus. To confirm aflatoxigenicity, amplification of the aflatoxin cluster genes produced fragments within the expected range (630-1490 bp). The genus Fusarium was more frequent in maize (46.2%), and the genera Aspergillus and Penicillium were more frequent in peanuts (100% and 58.3%, respectively). The genera Aspergillus and Penicillium occurred in all collection regions, while the genus Fusarium occurred in all regions except for the Manhiça and Manica regions. The high frequency of potentially aflatoxigenic isolates reinforces the need for continuous molecular monitoring to better understand fungal pathogenicity, environmental adaptation, and the implications for food safety and public health. (TRADUÇÃO NOSSA)