الفهرس 
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Abstract
The present study deals with the selective isolation of marine Actinomycete from different marine habitats in Egypt and identifying the most potent isolate(s) with the ability to produce antimicrobial agent(s) against the pathogenic test organism (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiala pneumonia, Pseudomonas aeurogenosa and Candida albicans).
A total twenty actinomycetes were isolated from the selected marine habitats. They were tested for their antimicrobial potentialities against the test organisms. One isolate was selected for further study No. I.12, as it was found to produce a wide spectrum antimicrobial agent(s) aganist Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiala pneumonia and Candida albicans. The cultural, microscopic, physiological, biochemical and molecular identification of the selected isolated strains No. I.12 proved that, it was similar to Streptomyces sp. 16S-rRNA was carried out; it showed that it was similar to Streptomyces sp. with comptability 98%.
Optimization of conditions for maximum productivity of antimicrobial substance was carried out; different N-source, different C-source, different media, pH, temperature, agitation and incubation period. It was reported that the isolated strain
Summary
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showed maximum productivity on starch nitrate medium containing starch as C-source and potassium nitrate as N-source at 28°C for 7 days, pH 7-7.5 and agitation speed 180 rpm.
The extracted antimicrobial agent(s) was partially characterized by TLC, IR, NMR and GC-Mass chromatography.
The compound was found to be aliphatic and similar to lankacidin antibiotic. It was suggested to be a methylated derivative of lankacidin