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دراسة التاثير المثبط لبعض انواع بكتريا حامض اللاكتيك ضد بعض انواع الفطريات الممرضة والمنتجة للسموم == Study The Inhibition Effect of Some Species of Lactic Acid Bacteria Against Some Pathogenic And Toxins Producing Fungi Types
Author name:
لؤي برهان مصطفى محمد
Supervisor name:
كركز محمد ثلج الجبوري
General topic:
Biology
Specific topic:
Microbiology
Degree:
Master
University:
Tikrit University - Faculty Of Education - Department Of Biology
Language:
Arabic
University location:
Salahaddin
First pages:
24T2794 - p.pdf
Abstract:
اجريت الدراسة في مختبرات قسم علوم الحياة في كلية التربية بهدف عزل وتشخيص بعض انواع بكتريا حامض اللاكتيك ومحاولة اختبار قابلية خلاياها او النواتج الايضية منها وكذلك دراسة تاثير المستويات المختلفة من درجة الحرارة والاس الهيدروجيني في القابليـة التثبيطية لب | This work aimed to investigate the effects of some lactic acid bacteria (LAB) species (cells or their metabolic products) at different temperatures and pH levels on some soil pathogenic or toxin produced fungi species. Six LAB isolates and the identification was depended on the morphological and cultural characterized and biochemical testes, the isolates were determined as Lactobacillus delubricii subsp. delubricii, Lactobacillus delubricii subsp. bulgaricus, Lactobcillus casei, Lactobacillus acidophilus, Leuconostoc mesentroides and Streptococcus thermophilus, and four fungal species Microsporum canis, Trichophyton mentagrophytes, Aspergillus fumigatus and Rhizopus stolinfer were identified. In this study the highest inhibition effect against the above mentioned fungi was shown by L. acidophilus as a significant (P< 0.05) efficacy where the diameter of inhibition zone in case of M. canis, T. mentagrophytes, A. fumigtus and R. stolonifer was 26, 32, 30 and 28 mm respectively. Less inhibition activity was exhibited by Leu. mesentroides and Str. thermophilus while the lowest inhibition was shown by L. delubricii. Results showed also that the temperature optimal for the growth of bacterial species (except L. casei and Str. thermophilus) tested and their inhibition activity was 30 °C. However, temperature of 35 °C was the optimal for the highest inhibitory effect of both L. casei and Str. thermophilus. At 25 °C of studied bacterial species showed decreased inhibitory effect against the tested fungi. Concerning the pH, the present study showed that the highest inhibitory of all tested bacteria species (except L. acidophilus) was at pH 6.5, L. acidophilus showed such activity at pH 5.5. This study revealed that the inhibitory effect of metabolites produced mixture of the tested bacterial species was directly proportional with its concentrate. Where this mixture was used at media concentration of 10, 20 and 40 mg/ml cultural. However, metabolic products from L. acidophilus, Leu. mesentroides and Str. thermophilus was the most effective in inhibition activity compared with the rest of the bacteria species used particularly at 40 mg/ml cultural media
