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الخصائص المظهرية والجزيئية للفطر Aspergillus niger وتقييم قابليته في انتاج حامض الستريك تحت ظروف مختلفة == Phenotypic And Molecular Characteristics of The Fungus Aspergillus Niger And Evaluation Its Ability To Produce Citric Acid Under Different Conditions
Author name:
علي عبد الهادي ماهود السوداني
Supervisor name:
ماجد كاظم عبود الشبلي
General topic:
Biology
Specific topic:
Microbiology - Fungi
Degree:
Doctorate
University:
University of Al-Qadisiyah - Faculty Of Education - Department Of Biology
Language:
Arabic
University location:
Qadisiyah
First pages:
24T2963 - p.pdf
Abstract:
نفذت هذه الدراسة لتقييم قابلية فطريات من التربة في انتاج حامض الستريك باستخدام وسط غذائي صناعي مدعم بمصادر كربونية ونيتروجينية واملاح وتحديد بعض الظروف المثلى للانتاج من العزلة الفطرية الاكفا بعد تنميتها على وسط المولاس المروق ووسط راشح قشور الرز المدعمين | This study was carried out to evaluation the ability of fungi from the soil in the production of citric acid using synthetic culture medium supplemented with sources of carbon, nitrogen and salts and determine some optimal conditions for the production of citric acid from the most efficient fungal isolate after growing it on the clarifying molasses medium and rice husks filtrate medium supplemented with some nutrients, and also determine the genotype for the most efficient fungal isolate in the production of citric acid by PCR - RFLP technique and determine the sequence of DNA bases for the region ITS1 - 5.8S rRNA gene - ITS2, and the study also included a purification of the citric acid by precipitation method and detection it by (HPLC) High Performance Liquid Chromatography. The results showed the presence of 21 fungal isolates included 12 isolates for the fungus Aspergillus niger by frequency amounted to 57.14 % and 5 isolates for the fungus Trichoderma viride by frequency amounted to 23.8 % and 4 isolates for the fungus Mucor spp. by frequency amounted to 19.04 %, were excluded from the study some fungal isolates which showing the ability to produce aflatoxins. The screening 16 local fungal isolates of fungi A. niger, T. viride and Mucor spp. it appeared that the fungal isolate A. niger 5 was the most efficient in the production of citric acid, and also the results showed a single two bands of DNA with a molecular size 480 and 66 base pairs at using RsaI restriction enzyme and that the genotype of the A. niger 5 is of the type A Some optimum cultural and environmental conditions for the production of citric acid from the selected isolate were studied. It was obtained the highest production of citric acid which amounted to 28.947 g/l at the clarifying molasses medium and 30.015 g/l at rice husks filtrate medium using 15 % reducing sugars, 0.25 % ammonium sulfate, 0.1, 0.2 % KH2PO4, 0.025 % MgSO4.7H2O, adjusted primary pH of medium to 3.5, 4 inoculated with 4 % from the initial inoculation which it concentration 1 x 106 spore/ml and incubated under shaker conditions at 200 rpm at 30 C for 8, 9 days for the clarifying molasses medium and rice husks filtrate medium respectively. The results of detected of citric acid using HPLC showed two peaks for both standard citric acid and citric acid under study at retention time amounted to 12.637 and 12.641 minutes respectively.
