Molecular identification of isolated fungi from stored apples in Riyadh, Saudi Arabia

Fungi causes most plant disease. When fruits are stored at suboptimal conditions, fungi grows, and some produce mycotoxin which can be dangerous for human consumption. Studies have shown that the Penicillium and Monilinia species commonly cause spoilage of fruits, especially apples. Several other genera and species were reported to grow to spoil fruits. This study was conducted to isolate and identify fruit spoilage by fungi on apples collected in Riyadh, Saudi Arabia and conduct a molecular identification of the fungal isolates. Thus, we collected 30 samples of red delicious and Granny Smith apples with obvious spoilage from different supermarkets between February and March of 2012 in Riyadh, Saudi Arabia. Each apple was placed in a sterile plastic bag in room temperature (25-30 °C) for six days or until fungal growth was evident all over the sample. Growth of fungal colonies on PDA was counted and sent for molecular confirmation by PCR. Six fruit spoilage fungi were isolated, including Penicillium chrysogenum, Penicillium adametzii, Penicillium chrysogenum, Penicillium steckii, Penicillium chrysogenum, and Aspergillus oryzae. P. chrysogenum was the most frequent isolate which was seen in 14 of a total of 34 isolates (41.2%), followed by P. adametzii and A. oryzae with seven isolates each (20.6%) and the least was P. steckii with six isolates (17.6%). Penicillium species comprised 27 of the total 34 (79.4%) isolates. Sequence analysis of the ITS regions of the nuclear encoded rDNA showed significant alignments for P. chrysogenum, P. adametzii and A. oryzae. Most of these fungal isolates are useful and are rarely pathogenic; however they can still produce severe illness in immune-compromised individuals, and sometimes otherwise healthy people may also become infected. It is therefore necessary to evaluate the possible production of mycotoxins by these fungi to determine a potential danger and to establish its epidemiology in order to develop adequate methods of control.