الفهرس 
Aim of the WorkOnly 14 pages are availabe for public view
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Abstract
The need for novel antimicrobial agents has become a global demand as the multidrug resistance pathogens have accelerated. In this work, marine sediment sample was collected from Red Sea, Egypt. from this sample, bacteria were isolated using Zobell 1/4 strength media at two different temperatures, 37°C and 28°C. Twenty five different bacterial isolates were obtained and screened for antimicrobial material production; only seven bacterial strains, that showed notable antimicrobial activities in the first round of screening, were introduced to a second screening round for antimicrobial activities using 3 different types of media: Zobell 1/4 strength, Luria-Bertani (LB) and Marine broth (MB) media. The isolate I9 showed inhibition zones in the range between 13-17 mm against different Gram positive, Gram negative bacteria and C. albicans. This bacterial strain I9, named Pseudomonas sp. strain ASA235, was subsequently identified by 16S rRNA gene nucleotide sequence and analysis. Phylogenetic analysis was performed and showed that the strain is most closely related to Pseudomonas aeruginosa DSM_50071T_HE978271.1 (100%) type strain. The obtained 16S rRNA gene sequence was submitted to the gene bank and assigned an accession number of MH580294. By using Central composite design, it was found that 35°C, pH 7 and 48h incubation time are the optimum physicochemical conditions for production. The best nutritional environment contained yeast extract and malt extract as nitrogen sources, galactose and lactose as carbon sources (were determined using Placket-Burman design) and NaCl. Antimicrobial materials from Pseudomonas aeruginosa strain ASA235 was extracted, purified and characterized to detect its chemical structure, it was found that one compound is pyocyanin and the other is phenazine1- carboxylic acid. The MIC of the crude extracts was 10 mg/ml against tested organisms.