الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In this investigation different bacterial isolates of fluorescent pseudomonads were obtained from the rhizosphere of some medicinal and conventional plants. These bacterial isolates were screened according to their biochemical activities including IAA, cyanide production, solublization of phosphorus and potassium and their activity to antagonise soil-borne pathogens. Pot experiment was carried out to evaluate the efficiency of two selective bacterial strains to provide tomato plants with plant nutrients and growth promoting substances.
These results could be summarized as follows:
1. Seventy one bacterial isolates were obtained from the root microbiome of some medicinal and conventional plants. They were found to belong to fluorescent pseudomonads.
2. These isolates are highly varied in their efficiency to produce IAA, cyanide production, able to solubilize both phosphorus and potassium with antagonistic effect against some soil-borne pathogens e.g. Rhizoctonia solani and Fusarium oxysporum.
3. Four isolates out of seventy one were selected as the most active fluorescent pseudomonads being OL2, SE8, OL4, AR10 (isolated from root microbiome of Olea europaea, Sesamum indicum, Olea europaea and Artemisia vulgaris respectively.
4. These isolates were subjected to identification using 16s rRNA gene sequencing technique. These isolates were found to be different strains of Pseudomonas otitidis.
5. Growth curves and growth kinetics of these bacterial strains using king’s medium and nutrient glucose broth medium were studied. The highest specific growth rate for all tested Pseudomonas strains was recorded in King’s broth medium than nutrient glucose broth medium. It means that all tested strains assimilated the nutrients of king’s medium more efficiency to biosynthesis of their cells constituents than nutrient broth.
6. The most active Pseudomonas strains were selected according to their biochemical activities being Pseudomonas otitidis OL2 and Pseudomonas otitidis SE8. These strains were assessed to solubilize 0.5% Ca3(PO4)2 in Pikoviskaya’s medium in shake culture during 20 days. It was found that the available phosphorus progressively increased during the first five days of incubation then become approximately constant up the end of the experiment.
7. These strains were inoculated in modified Alexandrov’s medium for 20 days at 28-30 ºC under shaking conditions to determine the available potassium. Pseudomonas otitidis OL2 and Pseudomonas otitidis SE8 gave 57.33 and 80.67 ppm respectively.
8. These strains were evaluated to produce IAA in King’s medium with or without treptophan. The maximum IAA production was recorded in case of Ps. otitidis SE8 (27.67 µg/ml) grown on King’s medium supplemented with tryptophan, whereas the lowest quantity was observed by Ps. otitidis OL2 being 10.95 µg/ml grown in King’s medium which tryptophan was omitted. Also, Pseudomonas otitidis OL2 and Pseudomonas otitidis SE8 gave 2.65 and 2.77 µg/ml respectively as gibberelic acid when were grown in King’s medium. The siderophore production by these strains was assessed.
9. Two Pseudomonas otitidis strains which showed high efficiency were propagated in shake flasks using rotary shaker (150 rpm) to produce Pseudomonas inoculum for pot experiment.
10. Pot experiments were designed to elucidate the role of two Pseudomonas strains on growth parameter of tomato plants and biocontrol of phytopathogenic fungi. Plant growth parameters of tomato were highly affected by Pseudomonas treatments where the inoculated tomato seedlings gave a pronounced effect on tomato growth parameters (fresh & dry weight and NPK values). Both tested bacterial strains and their mixture (Biocoktal) also led to protect tomato plants from the phytopathogenic tested fungi (Rhizoctonia solani and Fusarium oxysporum).