Characterization of the bacterial microbiota from traditional African spontaneously fermented foods and selection of candidates with potential effect on mycotoxigenic fungi

Mycotoxins are toxic secondary metabolites produced by filamentous fungi, which pose significant risks to human health and food safety due to their carcinogenic potential. The UP-RISE project is part of a broader food safety effort, which aims to reduce mycotoxin contamination, particularly from the five major mycotoxins (AFB1, FB1, OTA, DON, ZEN), along the African agri-food chain. Through a collaboration between EU and African partners, this initiative focuses on innovative and sustainable strategies to improve the quality of agricultural products and safeguard consumer’s health, in particular by exploiting fermentation techniques using selected microbial starters. This study presents preliminary results on the isolation of beneficial microorganisms from traditional African spontaneously fermented foods, for identifying potential microbial starters to improve food safety and quality. The foods analyzed include: Akpan (Ak) and its intermediate product Ogi (Og) from Benin, based on maize; Sorghum beer (Umqombothi) from local markets in South Africa (SB) and commercially available sorghum beer (OSB); and Maziwa Mala (ML) from Kenya, based on milk. In order to isolate beneficial microorganisms, these foods were homogenized and suspensions were plated onto MRS agar. A total of 20% of the colonies randomly picked from countable plates, were purified and stored at -80°C. The bacterial isolates were characterized by repetitive extragenic palindromic - PCR (REP-PCR) and isolates representative of each REP-PCR profile (26) were identified by sequencing of the 16S rRNA gene. A preliminary investigation was carried out on twelve strains (two Bacillus spp., eight Limosilactobacillus fermentum and two Leuconostoc mesenteroides) to assess their antifungal activity towards Fusarium graminearum ITEM 8318, a deoxynivalenol (DON) producer. The dual-culture assay was performed on solid nutrient medium such as MRS agar, potato dextrose agar (PDA), plate count agar (PCA) and tryptone soy agar (TSA). Results suggested a potential inhibitory effect up to 30 % from six L. fermentum strains and one Lc. mesenteroides strain. Further work has been planned in order to select strains for their ability to reduce the mycotoxin content during fermentation.