الفهرس 
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Abstract
DISSERTATION ABSTRACT : Legumes represent a huge group of plants included in a broad family named Fabaceae or Leguminosae. The presence of nodules in roots of legumes is known since the seventeenth century and they harbour two types of bacteria, the rhizobia, responsible for their formation, and other endophytic bacteria whose role in the nodule is still poorly known. Some of these endophytes are plant growth-promoting rhizobacteria (PGPR) that can promote plant growth through production of phytohormones and siderophores, nitrogen fixation and phosphate solubilization. PGPR can also promote plant growth through the control of Soilborne Diseases and were known as biocontrol agents. In this study the bacterial isolate Bacillus amyloliquefaciens isolated from root nodules of Phaseolus vulgaris was used as biocontrol agent against bacterial and fungal pathogens. The isolate was identified and had accession number MG214652 and so it has been given the name Bacillus MAP3. from the morphologically and physiologically characterization, the isolate Bacillus MAP3 was Gram positive spore forming bacilli. The optimum temperature and pH were determined for the isolate Bacillus MAP3 using Central Composite Design (CCD) matrix and it showed optimum growth at 35°C and pH 7. The isolate Bacillus MAP3 was tested for antimicrobial activity against 9 pathogens using disc diffusion method and shoed high effect against Erwinia carotovora and Bacillus subtilis, moderate effect against Candida albicans, weak effect against E.coli, Klebsiella spp, Staphylococcus epidermidis and Pseudomonas aeruginosa and there was no effect against Shigella spp. and Proteus vulgaris. The metabolites of isolate Bacillus MAP3 also showed high antimicrobial activity against Erwinia carotovora using well diffusion method. Antifungal activity of isolate Bacillus MAP3 was also tested against plant fungal pathogens Fusarium solani, Fusarium oxysporum and Sclerotinia sclerotiorum using the dual culture method. The results showed high growth inhibition of mycelium of the pathogenic fungi compared to the control. The antagonistic effect of volatile organic compounds (VOCs) produced by isolate Bacillus MAP3 was also tested against afro-mentioned phytopathogens using divided plates. Compared to the control plates the results showed that these VOCs have the ability to inhibit the growth of Fusarium solani (more than 80% inhibition) and the inhibition against Fusarium oxysporum and Sclerotinia sclerotiorum was about 50%. Scanning electron microscopy analysis of the margins of fungal pathogens Fusarium solani, Fusarium oxysporum and Sclerotinia sclerotiorum subjected to VOCs of Bacillus MAP3 was also performed to investigate the changes in the mycelial morphology compared to the control plates. The effect of VOCs on the hyphae showed abnormal distructions, swelling and surface subsidence compared to the control which were often multiseptate on the outer surface and were regular, intact, and plump. The total protein of afro-mentioned phytopathogens inhibited by isolate Bacillus MAP3 and uninhibited was extracted and investigated by using12.5% SDS-PAGE. The results showed changes in protein of pathogenic fungi since there were proteins that upregulated and others were downregulated when affected by isolate Bacillus MAP3 compared to the unaffected pathogens. The effect of isolate Bacillus MAP3 on antioxidant enzymes of pathogenic fungi was tested and it was noticed that the presence of Bacillus MAP3 significantly increased the activity of peroxidase and catalase enzymes produced by Fusarium solani while decrease the activity of SOD and GR enzymes. The presence of Bacillus MAP3 also increased the activity of peroxidase, catalase and SOD enzymes produced by Fusarium oxysporum while the activity of GR decreased and the activity of all these enzymes produced by Sclerotinia sclerotiorum was increased in the presence of Bacillus MAP3. The VOCs produced by isolate Bacillus MAP3 were identified by GC-MS technique and diversity 22 volatiles were characterized.