الفهرس 
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Abstract
The present study aimed to explore the molecular polymorphism of bacterial isolates from the Egyptian soils (e.g., alginate-producing Azotobacter) and to optimize their alginate production using some synthetic media and environmental organic wastes. In this regard, this study included 5 parts as follows:
1. Isolation of Alginate-Producing Azotobacter.
2. characterization of the Azotobacter Isolates.
3. Optimization of Alginate Production by Azotobacter.
4. characterization of Azotobacter Alginate.
5. Applications of Azotobacter Alginate.
The obtained results can be summarized as follows:
1. Isolation of Alginate-Producing Azotobacter
Different soil samples were collected from 10 governorates representing different environments and soil types distributed around the River Nile delta and remote desert area. The soil samples showed neutral pH and a moderate level of salinity. Fifty Azotobacter isolates were isolated from the collected soil samples.
2. characterization of Azotobacter Isolates
The isolates of Azotobacter were characterized based on their cell morphology, culture characteristics, physiological and biochemical traits and some molecular characteristics.
• Morphological characterization
All the isolates (50 isolates) were Gram-negative, short rods to oval cells that existed in single-cell structures or diploids. Fifty percent of the isolates produced brown-pigmented colonies. All the isolates formed mucoid colonies. Forty-two isolates were able to produce alginate and formed an alginate cyst.
• Biochemical and physiological characterization
Screening the isolates for alginate production indicated high variability. Two isolates obtained from Assuit (AST4) and El-Behira (BH3) were the highest alginate producers, but AST4 was higher than BH3. The isolates showed different capabilities of utilizing carbon sources, growing in different temperatures (30°C was the optimum), growing on different pH (pH 7 was the optimum) and different abilities to tolerate antibiotics. No relationship was found between the bacterial traits and the origin of isolation, except for temperature tolerance where isolates from the desert area and Upper Egypt were grouped together based on cluster analysis.
• Molecular characterization
Molecular characterization was performed using different fingerprinting techniques, including RAPD, REP and BOX-PCR fingerprinting. The results revealed that 6-9 profiles were obtained. REP and BOX were able to differentiate the isolate into species and strains within the same.