Abstract:

Abstract Date fruits are consumed in many countries globally and are mostly loaded with a mixture of microbes. As a result, various bacterial and fungal species attack them, thus causing their spoilage at the ripening, storage, and processing stages. The present study investigates the current spoilage bacteria and fungi of twelve postharvest date fruits collected from different Egyptian geographical regions (Aswan, Siwa, and El-Wady El-Gadeed). Isolation and identification of date-borne microbes based on morphological and molecular identification were studied. The microscopic examination of infected date samples showed various fungal structures (e.g., hyphae, spores, conidial head, etc.). In addition, all fungal structures observed in the infected specimens belong to the fungus Aspergillus niger. After six days of incubation on a PDA medium, the total viable counts of fungi in twelve date varieties samples ranged from 1500 to 80000 (CFU/g). Five fungal isolates were isolated (Aspergillus niger F4, A. terreus F1, Penicillium sp. F3, Rhizopus sp. F2, and Circinella sp. F5) from the different samples. A. niger F4 (GenBank accession number MW811390) was the most abundant in all samples. Similarly, the total viable bacteria counts in twelve date varieties samples ranged from 4500 to 75000 (CFU/g) after 48 h incubation on nutrient agar (NA) medium. Four morphologically different bacterial phenotypes (B1, B2, B3, and B4) were isolated and purified on the NA plates. Pseudomonas aeruginosa B1 (GenBank accession number MW811391) was the most abundant bacterial isolate in all samples. Aflatoxins were also analyzed using HPLC/MS/MS in all date varieties. The results showed that aflatoxins G2, G1, and B2 were not detected in all date varieties. However, aflatoxin B1 was detected in two varieties, Partamoda and Frehi.

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