الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Plant growth-promoting bacteria (PGPB) are bacteria that are free-living and have a symbiotic relationship with plants, as well as bacterial endophytes that can colonize plant tissue. Many bacterial endophytes have received much interest due to their ability to promote plant growth through direct mechanisms or as bio-control agents against pathogens by indirect mechanism. Endophytic organisms are found in a large array of niches in plants. As a result, there is a great chance that researchers may discover novel and helpful endophytic microorganisms among the variety of plants in various habitats. This study studied the potentiality of endophytic bacteria isolated from avocado fruits (Persea americana) in promoting of wheat plant seedling (Triticum aestivum) growth and producing high molecular weight polymers such as Exopolysaccharides (EPS). Following their selection and purification based on morphological differences, thirteen endophytic bacterial isolates were assigned the codes Avo-A1, Avo-A2, Avo-A3, Avo-A4, Avo-E1, Avo-L1, Avo-L2, Avo-L3, Avo-K1, Avo-K2, Avo-K3, Avo-K4, and Avo-K5. The bacterial isolates showed variation in size, shape, and colour on LB agar media. Six isolates were round-shaped and Gram-positive bacteria, four isolates were rod-shaped and Gram-negative bacteria, four isolates were rod-shaped and Gram-positive bacteria, and one isolate was round-shaped and Gram-negative bacteria, according to the microscopic analysis of the isolates. Tests for the biochemical characterization of endophytic bacterial isolates revealed that the greatest producers of lipase were Avo-A2, Avo-K5, Avo-L1, and Avo-L3. The best producers of amylase were Avo-A4 and Avo-K3, the best producers of cellulase were Avo-A2, and the best producers of protease were Avo-K3. Salinity tolerance of Avo-A3, Avo-L1, and Avo-K4 were the maximum at 10 % NaCl and only Avo-A1 and Avo-K1 exhibited inhibition zones with diameters of 20 mm and 15 mm, respectively, in the antibacterial activity of endophytic bacteria isolates against MRSA. The other bacterial isolates did not exhibit any inhibition zones.from wheat seed experiment, out of 13 bacterial isolates from avocado fruits, five isolates increased germination percent as well as number and length of adventurous roots and shoot length. The best treatment in wheat seed biopriming tests were Avo-A3 and Avo-A4, followed by Avo-L1, Avo-L2, and Avo-K4 isolatesAvo-A3 gave the highest ammonia (62.03 ± 1.76 mg/ml), Avo-L2 was the best IAA producer (58.29±1.47μg/ml), B. licheniformis Avo-L1 was the best GA3 producer (209.53 ± 3.59μg/ml), managed to grow on N₂ free medium and produce EPS.EPS is employed in many industrial and medicinal applications, including scaffolds, drug delivery systems, medical coating devices, surgical sealants, and anticancer activities. Only Bucillus licheniformis Avo-L1 was able to produce EPS. The production of EPS under optimal conditions (10 % sucrose and 72 hrs. incubation time) by B. licheniformis Avo-L1 gives 195.26 ± 2.99 mg/L. The bioactivities of the EPS generated by Bacillus licheniformis Avo-L1 are not well studied at the moment.