Document Details
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Document Type |
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Thesis |
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Document Title |
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Inhibition of Toxigenic Microorganisms by Lactic acid bacteria, Isolated from Milk and Fermented Food تثبيط الميكروبات المنتجة للسموم بواسطة بكتيريا حمض اللاكتيك المعزولة من الحليب و الغذاء المخمر |
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Subject |
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biological sciences department |
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Document Language |
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Arabic |
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Abstract |
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Twenty one bacterial isolates were obtained from the normal habitats of lactic acid bacteria (LAB). They were isolated from women milk, sheep milk, yoghurt, pasterilized milk and fermented food" pickles". Screening of all isolates of LAB for antimicrobial activity on MRS medium revealed that the highest antimicrobial activities were against Aspergillus niger, Penicillium. sp., Aspergillus flavus, Aspergillus ochraceus and Fusarium sp. No activity was observed against A. ochraceus and Fusarium sporotrichoides. The isolate S2 was the most active isolate and it was characterized and identified through physiological and biochemical tests, in addition to examination with light and scanning electron microscope as Lactobacillus bulgaricus S2. The bacterial filtrate was effective against Methicillin-resistant Staphylococcus aureus, Klebsilla pneumoniae, Bacillus sp., Staphylococcus aureus, Escherichia coli, Enterobacter sp., Acinetobacter sp., Micrococcus sp., Salmonella sp., Pseudomonas aeruginosa, Candida albicans, Alternaria sp., Trichosporon mycotoxinivorans and Cladosporium sp. The maximum antimicrobial activity of the selected isolate S2 was achieved using MRS medium after 48 hours of incubation in aerobic conditions at 30oC and pH 6 of the culture medium. The antimicrobial agent was extracted and purified using column chromatography. Its molecular weight was determined using Bio gel P2 to be a protein. The active material affected the growth, morphology, cells number and cell wall composition of Gram-positive bacteria. Moreover, the active material also affected the fungal numbers, growth, morphology and aflatoxins production of A. flavus. The antimicrobial compound decreased the total count of bacteria in grounded meat that indicates its potential application as a biopreservative. |
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Supervisor |
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Prof. Magda Mohammad Aly |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1433 AH
2012 AD |
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Co-Supervisor |
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Prof. Fardos M. Bokhari |
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Added Date |
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Tuesday, May 29, 2012 |
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Researchers
| وداد محمد الحيك | Al-Haik, Wedad Mohammed | Researcher | Master | |
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