ISOLATION AND IDENTIFICATION OF FUNGI ASSOCIATED WITH THE SPOILAGE OF SOLANUM LYCOPERSICUM (TOMATOES) SOLD AT MADORAWA MARKET
Abstract
The aim of this study was to isolate and identify fungi associated with the spoilage of Solanum lycopersicum (tomatoes) sold in Madorawa Market, Sokoto Metropolis. A total of eight (8) tomato samples showing visible signs of deterioration were randomly collected from different vendors in sterile polythene bags to prevent external contamination. The samples were transported under aseptic conditions to the Microbiology Laboratory of Sokoto State University, where analyses commenced within 24 hours. Fungal isolation was carried out using serial dilution and plating techniques on Potato Dextrose Agar (PDA), followed by incubation at room temperature for 5 to 7 days. Distinct fungal colonies were sub-cultured to obtain pure isolates, which were subsequently identified based on macroscopic and microscopic characteristics using lactophenol cotton blue staining. Pathogenicity tests were performed on healthy tomatoes to confirm the spoilage potential of each isolate. The results revealed six fungal genera: Aspergillus flavus, Aspergillus niger, Fusarium spp., Penicillium spp., Rhizopus spp., and Alternaria spp. The most frequent fungi were Aspergillus niger and Penicillium spp. (25% each), while Fusarium, Rhizopus, Alternaria, and A. flavus each accounted for 12.5%. Pathogenicity assays showed that Rhizopus spp. (15 mm zone of inhibition) and Fusarium spp. (10.5 mm) exhibited the highest levels of tissue degradation. The study concludes that tomato spoilage in Madorawa Market is predominantly caused by Aspergillus, Penicillium, Rhizopus, Fusarium, and Alternaria species, with wounding significantly increasing susceptibility to fungal invasion. It is recommended that vendors and farmers adopt proper post-harvest handling, maintain hygienic storage conditions, and explore natural antifungal treatments to minimize tomato losses and enhance food safety.
Keywords: Solanum lycopersicum, fungal spoilage, Aspergillus niger, Penicillium, Rhizopus, Madorawa Market, post-harvest handling.
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