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Document Type |
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Thesis |
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Document Title |
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CHARACTERIZATION OF PROBIOTIC LACTIC ACID BACTERIA ISOLATED FROM RAW MILK AND FERMENTED MILK PRODUCTS توصيف بكتيريا حمض اللاكتيك المعززة للصحة المعزولة من الحليب الخام و منتجات الحليب المتخمرة |
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Subject |
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Faculty of Sciences |
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Document Language |
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Arabic |
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Abstract |
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The aims of study were to isolate and identify lactic acid bacteria (LAB) and evaluate their therapeutic and food preservation importance. Ninety-three suspected LAB were isolated from thirteen samples of raw milk and fermented milk products manufactured in Saudi Arabia. Forty-six selected LAB strains were identified phenotypically and molecularly using 16S rDNA gene sequencing. The identified strains belonged to: Enterococcus (16 strains), Lactobacillus (9 strains), Weissella (10 strains), Streptococcus (8 strains) and Lactococcus (3 strains). The probiotic potentials of the strains have been investigated (antibiotics susceptibility, hemolytic activity, acid resistance, bile salts tolerance and antibacterial activity). None of the strains exhibited resistance to clinically relevant antibiotics or undesirable hemolytic activity and they were considered as safe, while they differed in other probiotic characteristics. 65.2 % and 71.7 % of strains exhibited tolerance 95 % viability to pH 3.0 and to 0.5 % w/v bile, respectively. Their antibacterial activities were different in the nature of inhibitory compounds. The minimum inhibitory concentrations (MICs) of seven strains were evaluated. Lb. casei MSJ1 inhibited the growth of Shigella sonni and M. luteus by 0.0376 mg/mL as the least MIC value. In conclusion, the Lb. casei MSJ1, Lb. casei Dwan5, Lb. plantarum EyLan2 and Ent. faecium Gail-BawZir8 isolates were likely the best probiotics and we speculate that studying the synergistic effects of bacterial combinations might result in the occurrence of more effective potentials, and that the obtained LAB may be further in another future study. We argue that the mentioned samles, especially stirred yogurt (Laban) made from camel milk, are rich in LAB with promising potential. |
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Supervisor |
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Prof. Rashad rizq Al-Hindi |
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Thesis Type |
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Doctorate Thesis |
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Publishing Year |
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1439 AH
2017 AD |
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Added Date |
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Thursday, November 16, 2017 |
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Researchers
| ماجد سالم مسلّم | Masalam, Maged Salem | Researcher | Doctorate | |
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