Species Composition and Frequency of Aspergillus and Penicillium on Stored Maize Grain Under Variable Humidity

Abstract

Variation in storage humidity markedly influenced fungal colonization patterns and community structure of Aspergillus and Penicillium spp. associated with stored maize grain. Stored grain samples were evaluated under different relative humidity regimes, and fungal isolation was performed using standard serial dilution and plating techniques on selective media. Morphological characterization enabled identification of dominant fungal taxa, while frequency of occurrence, relative abundance, and colony-forming unit (CFU) loads were quantified to assess community structure. Results indicated a clear humidity-dependent shift in fungal composition, with Aspergillus spp. exhibiting significantly higher frequency and dominance under high-humidity conditions, particularly aflatoxigenic species such as A. flavus, whereas Penicillium spp. were comparatively more prevalent under moderate humidity levels. Low-humidity conditions restricted overall fungal proliferation and reduced CFU counts across both genera. Diversity indices revealed decreased species evenness and increased dominance in high-moisture environments, reflecting strong environmental filtering effects. Statistical analysis demonstrated a positive correlation between relative humidity and total fungal load, highlighting moisture as a critical driver of post-harvest mycobiota dynamics. The interaction between storage conditions and fungal succession patterns underscores the risk of mycotoxin contamination in inadequately dried maize grains. These findings emphasize the importance of maintaining optimal storage humidity thresholds to suppress toxigenic fungal growth and preserve grain quality. The study provides insight into ecological behavior of storage fungi and supports the development of improved post-harvest management strategies for reducing fungal spoilage and associated food safety risks in maize storage systems.