Isolation and Identification of Fungi Associated with Post-Harvest Spoilage of Apple (Pyrus Malus) Traded in Kano Metropolis, Nigeria

Abstract

Storage of fruits at suboptimal condition provides fungi to grow and some produce mycotoxins, which can be dangerous/harmful for human consumption. This study was conducted to isolate and identify fungi associated with spoilage of apples sourced from Kano markets, Nigeria. A total of nine (9) fresh apple samples were collected randomly from different supermarkets on September of 2023 in Kano, Nigeria. Each apple was placed in a sterile plastic bag at room temperature (25–30°C) for fifteen days or until fungal growth was evident all over the samples. Growth of fungal colonies on Potato Dextrose Agar (PDA) was observed and molecular confirmation by Polymerase Chain Reaction (PCR) was conducted along with sequencing (sanger sequencing). Four fruit spoilage fungi were isolated, namely: Aspergillus fumigatus, Aspergillus niger, Curvularia spp, and Yeast spp. Out of the 9 samples that were analyzed, A. fumigatus and Curvularia spp were the most frequent isolates, A. fumigatus was seen in a total of 3 isolates (33.33%), Curvularia spp in 3 isolates (33.33%), A.niger in 2 isolates, and the least was Yeast spp seen in 1 isolate (11.11%). Sequence analysis of the Internal Transcribed Spacer regions of the nuclear encoded rDNA of the A.fumigatus isolate showed significant alignments for Penicillium griseofulvum. This is a potential refinement of the initial morphological characterization. The unexpected identification underscores the significance of incorporating molecular methods in fungal identification processes. The variation between initial morphological identification and molecular results emphasizes the need for precise and accurate identification techniques, particularly when dealing with closely related species. Most of these fungal isolates are pathogenic and can still produce severe illness in immune-compromised individuals, and sometimes otherwise healthy people may also become infected. The study highlights the limitations of traditional fungal identification techniques, as molecular analysis revealed Penicillium griseofulvum instead of the initially identified Aspergillus fumigatus in fungi from damaged apples. This underscores the importance of integrating molecular methods with conventional approaches for accurate fungal identification, vital for managing postharvest losses and ensuring food safety.