LC-MS Profiling for Studying the Impact of Environmental Factors on Fungal Pathogen Metabolism in Paddy Fields

This study hypothesizes that specific environmental conditions-particularly moisture and nutrient levels significantly influence the production of aflatoxins in Aspergillus niger isolated from paddy crops. Aflatoxins are toxic secondary metabolites with serious implications for food safety, especially in improperly stored grains. Understanding the metabolic responses of A. niger under such stress conditions is essential for designing effective storage and post-harvest management strategies.

The dominant fungal strain, designated as Monika AN-03, was isolated from infected rice grains collected from local storage warehouses. The strain was identified at the species level as Aspergillus niger through 18S rRNA gene sequencing and the sequence was submitted to NCBI under accession number OR083359. Morphological characteristics of the strain were studied using Scanning Electron Microscopy (SEM) to confirm conidial structure. To analyze the metabolic profile, the strain was cultured under nutrient-rich conditions and metabolite extraction was carried out. Liquid Chromatography-Mass Spectrometry (LC-MS) was employed to detect and quantify secondary metabolites, particularly aflatoxins.

The LC-MS analysis revealed distinct peaks corresponding to aflatoxins B1, B2, G1 and G2, confirming the ability of A. niger strain AN-03 to produce mycotoxins under conducive environmental conditions. These findings highlight the strain’s pathogenic potential and raise concerns about fungal contamination in storage environments. The data suggest that environmental stressors can activate specific metabolic pathways responsible for toxin biosynthesis, underlining the necessity for effective monitoring and environmentally sustainable control strategies in post-harvest grain management.