Microscopic studies on the Aspergillus flavus infected kernels of commercial peanuts in Georgia

Abstract

This article describes the use of microscopy to prove the presence of the aflatoxin producing pathogen, Aspergillus flavus Link ex Fries in commercially available edible peanuts in Georgia. Light microscopy in combination with electron microscopy has been used to describe the infection course established by the fungus. The alkali maceration technique used in the study was successful and sufficient to detect the kernel infection of A. flavus and monitor the infection percentage in edible peanuts. Percentage of infected kernel varied from one commercial outlet to another in the region. Briefly, peanut seeds from Cartersville had the highest percentage of A. flavus infection. Electron microscopy confirmed the seed-borne infection of this mold. Mycelium established inside the host tissues both intercellularly and intracellularly aided by active, continuous branching of young hyphae. Establishment of mycelium was also detected in the xylem vessels of roots indicative of systemic infection. Thus, edible peanuts can form an important source of inoculum and facilitate the spread of the fungus from one peanut to another in commercial outlets and elsewhere. Present study provides strong evidence that A. flavus can escape detection at selling points and lands in commercial outlets via edible peanuts. That these contaminated peanuts could pose public health hazards is discussed.