الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Biological Nitrogen fixation is a renewable source of nitrogen for agricultural soils, supplying the soil with more than half the amount of nitrogen fixed by other organisms. Vicia fabae and Phaseolus vulgaris is a major leguminous crop grown around the world and is most intensively cultivated in the North East Africa. In Egypt, Vicia fabae and Phaseolus vulgaris is considered as one of the most important food legumes and plays a major role in the Egyptian diets. Rhizobium is able to from nitrogen-fixing root nodules as a result of exogenous N fertilizers. Inoculation of legumes with rhizobia strains selected for high N2-fixing capacity can improve nitrogen fixation in agriculture, particularly when native rhizobia strains are absent or ineffective.
Many microbes can store non-nitrogenous organic materials within their cells such as polysaccharides, lipids, Poly-β-Hydroxybutyrate (PHB) or some inorganic substances such as polyphosphate. They are used as an internal energy source. Nutritional deficiency is like an important element of the environment. To his thesis deals with the study of Poly-β-Hydroxybutyrate, as an example of stored energy materials, by some microbes, especially bacteria, which are symbiotic of atmospheric nitrogen, because of its vital importance.
The aim of this study is to isolate and purify the Rhizobium isolates with high efficiency to stabilize air nitrogen with the roots of their hosts (Vicia fabae and Phaseolus vulgaris) and highly efficient in accumulating of PHB inside their cells and to determine the growth conditions that promote the accumulation of polymer inside bacterial cells (different carbon and nitrogen sources) and define the most efficient isolates. Bacteria capable of fixing nitrogen and accumulating the highest percentage of polymer within their cells and defined by the 16S rRNA ribosomal nucleotide sequence. The interaction between dietary and environmental factors to improve the production of PHB has been studied by applying a statistical program in the Response Surface Methodology and determining some physiological functions of this compound as well as its tolerance to different stress conditions as well as the response of Vicia fabae and Phaseolus vulgaris to pollination of nitrogen stabilizers containing high percentage of this. Compound under water stress conditions.
On the light of the previously mentioned objectives, the results of the study can be summarized as follows:
1. 58 Rhizobium isolates were obtained from root beans of Vicia fabae plant and 50 isolates were obtained from root Phaseolus vulgaris and growing beans in different regions from 9 different governorates in the Arab Republic of Egypt. Also, the ability of these isolates to form an honest contract on the roots of their specialized families was tested and their ability to fix nitrogen was measured by measuring the nitrogenase enzyme activity of these isolates.
2. Out of the 108 isolates, 10 rhizobial isolates (F14, F26, F28, F44 and F56) and (P4, P12, P25, P32 and P46) were selected to represent the most efficient PHB production for Vicia faba and Phaseolus vulgaris isolates, respectively.
3. Plant growth parameters were studied to select the most efficient isolates, F44 was the highest significantly isolate affected plant growth parameters recorded 88 mg/plant, 0.827 mg/ 100g nodules, 1.267 g/pant, 2.810 g/plant, 3.99%, 0.957μ/mol, 2.169 g/l and 0.976 g/l for Nodules dry weight, leghaemoglobin content, Rot dry weight, Shoot dry weight, %Nitrogen, Nitrogenase, Cell dry weight and contents of cells from PHB respectively. P32 was the highest significantly phaseolus isolate recorded 110 mg/plant, 0.792 mg/ 100 g nodules, 0.995 g/pant, 1.842 g/plant, 2.70%, 0.959 μ/mol, 2.555 g/l and 0.963g/l for Nodules dry weight, Leghaemoglobin content, Rot dry weight, Shoot dry weight,%Nitrogen, Nitrogenase, Cell dry weight and contents of cells from PHB respectively.
4. One variable at a time approach was studied to select the most significant carbon sources (Glucose, Galactose, Dextrose, Fructose, Mannose, Sucrose, Raffinose, Arabinose, Xylose and Maltose) affecting PHB production by both of Rhizobium fabae and Rhizobium phaseoli. Five organic and inorganic nitrogen sources (Yeast extract, Peptone, Glycine, Urea and KNO3) were also tested. It was found that yeast extract and glycine yielded the highest accumulation of polymer in all tested isolates. Mannitol and Sucrose the most signfecant efficient carbon sources used for PHB (%) production.
5. Based on morphological characteristics, gram staining, and further confirmation by sequencing the 16S rRNA gene, the isolates F44 and P32 were identified as Rhizobium fabae and Rhizobium phaseoli, respectively.
6. Rhizobium fabae and Rhizobium phaseoli strains were selected for the optimization of PHB production using a Response surface methodology (RSM). Eleven variables including culture conditions (pH, incubation period, inculum size, temperature and agitation speed) nutritional factors (media components), as mannitol, sacrose, yeast extract, glycine, K2HPO4, and MgSO4 were analyzed by plackett-Burman Design for their effects on PHB production, it was concluded that the optimal levels of the process variables for maximum concentration of PHB by Rhizobium fabae were obtained when grown on medium containing 25 g/l Sucrose, 0.5 g/l yeast extract, 05 g/l K2HPO4, 0.2 g/l MgSO4, 0.1 g/l NaCl, 7 pH, at 30oC, 7 ml inoculum size, (150 rpm) for 2 day incubation time. Whereas the optimal levels of the process variables for biosynthesis of PHB by Rhizobium phaseoli to achieve a maximum concentration of PHB are in the medium containing 25 g/l Sucrose, 0.87 g/l glycine, 1.0 g/l K2HPO4, 0.3 g/l MgSO4, 0.1 g/l NaCl, 7 pH, 5 ml incubation size, under shaking condition (150 rpm) at 30°C for 3 day the optimal levels.
7. A series of experiments were conducted to compare the physiological behavior between cells with high polymer content after the improvement process on the modified medium and those strains developing on the basic medium. The results showed that rich cells have more ability to survive without nutrients compared to those with low polymer content. It was found that both strains growing on the modified environment showed greater ability to grow in relatively high concentrations of sodium chloride up to (5%) compared to those developing on the basal environment. Both breeds gave the ability to grow at the temperature of 40oC compared to the same isolates that were developed on the basic environment. Basal environment. The results showed that the growth of both strains was generally low with pH levels rising above 10. both strains showed their ability to withstand the difficult environmental conditions (drought) by adding different concentrations of polyethylene glycol.
8. Response of Vicia fabae and Phaseolus vulgaris plants to inoculation of Poly-β-Hydroxybutyrate rich or poor cells under water stress conditions. Vicia fabae and Phaseolus vulgaris were experimented with different treatments of nitrogen-fixing rhizobia strains under study with high or low polymer levels. The experiment lasted for 5 weeks under the influence of different levels of water requirements on the growth of Vicia fabae and Phaseolus vulgaris plants.The results showed that the activity of the enzyme nitrogenase and the ratio of total nitrogen and the amount of lighemoglobin within the contract and the preparation of the contract on the host plant islands, as well as the dry weight of both vegetative and island total in the case of using the developing vaccine on the modified medium and contains a high percentage of polymer than those vaccinated with developing vaccine on Basic medium.
9. Considering the effect of water requirement on the growth of Vicia fabae and Phaseolus vulgaris plants, the results showed that plants pollinated with developing inculated on the modified medium and high in its polymer content were not affected by the decrease of irrigation rate by 80% compared to the plant that was inculated with the developing inculam on the basal medium in terms of dry weight. The total vegetative and root and also the percentage of nitrogen within the plant.