Storage Fungal Load, Community Diversity, and Mycotoxigenic Risk in Stored Groundnut Seeds Across Niger State, Nigeria

Abstract

Postharvest losses in stored groundnut remain high across Niger State, Nigeria, driven substantially by fungal colonization under the region's humid, high-temperature storage conditions. This study assessed fungal load, mycoflora community structure, and qualitative toxigenic potential across twelve Local Government Areas (LGAs) spanning three agro-ecological zones, using 98 seed samples analyzed by standard microbiological isolation and toxigenic screening on Coconut Agar Medium under UV fluorescence (365 nm). Fungal load ranged from 11 × 10³ CFU/g (Chanchaga) to 28 × 10³ CFU/g (Mokwa), with the highest-burden LGAs concentrated in the wetter south-western storage belt. A total of 346 isolates spanning six genera were recovered, dominated by Aspergillus spp. (67.4%; principally A. niger, A. flavus, A. fumigatus), and 58.0% (n = 201) of isolates showed potential for mycotoxin production. Multivariate community analysis (PCA, hierarchical clustering) and diversity indices (mean H' = 2.02, J' = 0.92) resolved three geographically coherent storage-risk zones, extending prior isolate-frequency surveys of Nigerian stored groundnut mycoflora by linking community structure directly to spatial storage risk. These findings support targeted, zone-specific postharvest management to reduce losses and consumer exposure to mycotoxins.