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Document Type |
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Thesis |
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Document Title |
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Mycoflora associated with apple spoilage and mycotoxins reduction by probiotic bacteria العنوان: الفلورا الفطرية المصاحبة لتعفن التفاح وخفض السموم الفطرية بواسطة بكتيريا البروبيوتيك |
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Subject |
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Faculty of Science |
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Document Language |
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Arabic |
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Abstract |
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Fungi can contaminate a wide range of agricultural crops, such as vegetables, cereals, and fruits. Fruits are an essential source of nutrients for human requirements. They contain many carbohydrates, minerals, vitamins, and amino acids, making them desirable for fungal growth. Accordingly, more than 39 species belong to 5 genera of fungi were isolated from 40 fresh apple and 20 dried apple samples collected from different markets in Jeddah, Saudi Arabia. The streaking plate method was used for fresh apples and the direct plating method for dried apples. The predominant fungi were Penicillium (94.0%), Aspergillus (2.6%), and Alternaria (2.2%). The most common species was Penicillium sp. About 50 isolates of Penicillium sp were screened by thin-layer chromatography (TLC) for their ability to produce toxic metabolites by calculating the Rf value. Two isolates of penicillium were found to have the ability to produce patulin, and it were defined by molecular identification, were found belonged to the genus Penicillium expansum and Penicillium chrysogenum. To confirm toxin production by these two strains brine shrimp larvae test was done. Experiments were conducted to study the effects of physical factors (temperature and Ph) and chemical factors (media) on fungal growth and PAT production for both P. expansum and P. chrysogenum in the potato dextrose broth medium (PDB). The optimum temperature for fungal growth and PAT production was 25 °C, and the optimum pH was between 5.5 to 7.5. The potato dextrose broth medium (PDB) and the apple medium were the best media for fungal growth and PAT production. Therefore, an experiment was conducted to simulate the natural development of fungi and the production of mycotoxins on a natural medium (fresh apple) during two weeks of storage. The second part of the research was to investigate the effect of probiotic bacteria found in natural apple cider vinegar products (Organic, unpasteurized, and unrefined). Five bacterial species were isolated from natural apple cider vinegar using MRS agar medium at a temperature of 37° C. The bacterial isolate R3 showed the greatest antagonistic effects on P. expansum and P. chrysogenum. Therefore, was characterized and identified through physiological and biochemical tests, and molecular identification. The chosen isolate R3 found belonged to the genus Lactobacillus plantarum. The antifungal activity of the L. plantarum was achieved against the growth of the two toxigenic fungi and their ability to inhibit the production of PAT. |
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Supervisor |
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Prof. Dr. Fardos Bokhari |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1444 AH
2022 AD |
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Co-Supervisor |
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Dr. Azhar Najjar |
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Added Date |
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Monday, February 27, 2023 |
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Researchers
| رهف حسن آل زين | Alzain, Rahaf Hassan | Researcher | Master | |
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