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العنوان
ASSESSMENT OF BIODEGRADATION OF POLYNUCLEAR AROMATIC COMPOUNDS USING MICROORGANISMS /
المؤلف
Nwashy, Dina Fikry Abd Eltawab Elsayed.
هيئة الاعداد
باحث / Dina Fikry Abd Eltawab Elsayed Nwashy
مشرف / Yousseria M. Hassan Shetaia
مشرف / Ashraf Y. El-Naggar
مناقش / Nashwa Abbas Ahmed
تاريخ النشر
2018.
عدد الصفحات
220 P. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
علم الأحياء الدقيقة
تاريخ الإجازة
1/1/2018
مكان الإجازة
جامعة عين شمس - كلية العلوم - قسم الميكروبيولوجى
الفهرس
Only 14 pages are availabe for public view

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from 220

Abstract

The great increase of populations and industrial development during the last century has increased the demand for hydrocarbons (HCs) like petroleum and its products since they have become a major energy source. The accidental releases of these HCs into the air, water and soil represent potential environmental and health hazards.
For this reason, the work presented in this thesis was initiated with an aim to isolate efficient PAH degrading microorganisms and use them in bioremediation of PAH polluted sites.
Three aromatic HCs were used, which represent their families; xylene (i.e. representative of monoaromatics), naphthalene (i.e. representative of diaromatics) and anthracene (i.e. representative of polyaromatics). Four isolation samples were brought from Suez, Giza and Helwan cities and were used to isolate either xylene or naphthalene or anthracene degrading microorganisms. The screening of aromatic HC-degrading microbes resulted in the isolation of one hundred and thirty nine microorganisms.
The abilities of these microbial isolates to degrade any of the three used c-sources have been investigated on two levels; using individual aromatic HC then a mixture of these three aromatic HCs as a sole c- source.
The screening process resulted in the selection of the three most potent microbial isolates; bacterium (BN24), actinomycete (AX3) and fungus (FX8), using a mixture of xylene, naphthalene and anthracene as a sole c-source.
Only two microbial isolates were used to complete the perspective of this study; the most potent bacterial isolate, which was isolated from one of the two oil samples, and the most potent fungal isolate, which was isolated from one of the two crude oil-polluted water samples.
For the bacterial isolate, the optimum degradation conditions for the
maximum aromatic HC-degradation were 1% (v/v) of the c-source, PH 7, 37°C and 200 rpm; while for the fungal isolate were 1% (v/v) of the
c-source, PH 4, 30°C and 150 rpm.
The degradation potentials of both microbial isolates toward the studied aromatic mixture (xylene, naphthalene and anthracene) were also confirmed by CGC-MS analysis. The bacterial isolate was able to degrade 66% xylene, 70% naphthalene and 89% anthracene after 2 days under optimum conditions, while the fungal isolate was able to degrade 81% xylene, 73% naphthalene and 94% anthracene after 3 days under optimum conditions.
The two most potent microbial isolates were identified by using 16S rRNA for the bacterial isolate and slide culture technique for the fungal isolate. They were identified as Bacillus licheniformis strain DSM 13 and Aspergillus flavus.
To evaluate the degradation efficiency of these two most potent microbial isolates, they were subjected and applied to the wider and more complex HC mixtures, BTEX and crude oil containing aromatic HCs. Then their degradation potentials against each of these mixtures were assessed via CGC-MS for BTEX mixture and HPLC analysis for petroleum oil sample.
Bacillus licheniformis strain DSM 13 was able to degrade 97.43% of the total BTEX mixture after 48hrs, while Aspergillus flavus was able to degrade 87.97% of the same mixture after 4 days. In case of using the mixture of aromatics as a sole c-source, Bacillus licheniformis strain DSM 13 and Aspergillus flavus were able to degrade 95.3% and 85.5% of this mixture of aromatic HCs in petroleum oil, respectively, after 4 days.
from all the previous results, it was denoted that both Bacillus licheniformis strain DSM 13 and Aspergillus flavus can be considered the most efficient microbes in degrading complex and wide range of aromatic HCs in a short time period. So, we can take benefit from these time and money saving microbes in remediating HC-polluted sites.