Document Details

Document Type : Thesis 
Document Title :
Studies on nitrogen fixation efficiency of some Rhizobium spp. using molecular genetics techniques
دراسات على كفاءة تثبيت النيتروجين لبعض أنواع الرايزوبيا بطرق وراثية جزيئية
 
Subject : biological sciences department 
Document Language : Arabic 
Abstract : About 17.2 X 107 tons of nitrogen is biologically fixed annually all over the world.Research to improve biological nitrogen fixation (BNF) is progressing through the breading of efficient N2- fixing organisms and host plants, selection of the best combination of the host plant and microsym biont, and by improvement of inoculation techniques and field management. Leguminous plants can obtain most of the nitrogen they need from the vast supply of gaseous nitrogen in the air. They gather and use this nitrogen by working symbiotically with special rhizobia in nodules on their roots. Legumes also leave some of the fixed nitrogen in the soil. They are by far the largest source of organic nitrogen in the global nitrogen cycle. Different ecological factors are dramatically affecting the legume/rhizobia symbiosis. Therefore, enhancing the BNF requires the investigation of some of the factors involved in this relation. Salt and heat tolerant is a growing problem in arid countries such as in KSA. Several reports indicated this problem in soil. Many bacterial strains contain genetic determinants of resistance to antibiotic, salt, heat and genes essential on these resistance are often found on plasmids. This study aim to isolate and characterize new Rhizobium strains more competitive than usually in use inoculants, and to study some characters related to competition ability between the same species or other related microorganisms by study their resistance to antibiotics produced by other related microorganisms or some other important ecological factors, e.g., salt , heat, Also study some genetic characters of isolated strains such as plasmid profile and fingerprinting of strains using different methods of RAPD-PCR and restriction enzyme fingerprinting. The main results obtained in this study are summarized in the following points: Nodulation efficiency was studied on all Strains and there were different levels of nodulation efficiency between studied strains. Antibiotic resistance was also studied using antibiotic disks and results have showed different resistance in studied Rhizobium strains to antibiotics. Rhizobium strains were studied for salt-tolerance by adding different concentrations of sodium chloride in a liquid media .The ratio ranged was between 0.5 to 4% sodium chloride and it was found that Rhizobium strains under study have tolerated salinity to 3.5% in the liquid media and one strain was able to grow in 4% concentration. Studying the growth of strains under different temperatures ranging from 30oC to 60oC resulted that all strains are capable of growth up to 45oC and one strain was able to grow up to 55oC. Plasmids analysis of studied strains proved that there are similarities in the number, size and patterns, which shows similarities on the plasmid level. Fingerprinting of strains under study using the technique of RAPD_PCR showed difference between the strains in their amplified bands which represents the genetic difference among them. Genomic DNA was cut using restriction Enzymes. 
Supervisor : Dr. Salah El-Dien Abou - Aba 
Thesis Type : Master Thesis 
Publishing Year : 1433 AH
2012 AD 
Co-Supervisor : Dr. Mohammed Hamed Zainy Mutwakil 
Added Date : Tuesday, December 4, 2012 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
تركي مسعود الأحمديAL-Ahmadi, Torki MasoudResearcherMaster 

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