The study included the selection of local marine bacteria isolates that were isolated from the sediments of the coastal waters of Lattakia, and theiridentity was determined using a number of agricultural, morphological and biochemical tests as being species belonging to the genus Bacillus. The inhibitory activity of different concentrations of the organic extracts of these bacterial isolates against some pathogenic bacteria (Streptococcus pneumoniae and Staphylococcus aureus) and Gram-positive

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... acteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia) were studied using the gram-negative diffusion method. The inhibitory effect of this organic extract was then compared to that of some commercial antibiotics.The results showed that the biological activity of the organic extract of isolates of the genus Bacillus sp (B. subtilis, B. polymyxa, B. cereus, B. circulans) showed that the largest inhibition halo diameter of B. subtilis extract towards S. aureus was 26 mm and it was the lowest halo diameter for bacteria. P. aeruginosa was 13mm. As for B. polymyxa extract, the highest inhibition halo diameter was 27 mm against S. pneumoniae and 25 mm against S. aureus, and the lowest diameter of inhibition was recorded as 13 mm against P. aeruginosa. In relation to the extracts of other species of the genus Bacillus sp (B. cereus, B. circulans), the inhibitory activity of their extracts was higher against Gram-positive bacteria than against Gram-negative bacteria. These bacterial extracts of Bacillus sp were more effective than various commercial antibiotics used.