Isolation of Antibiotic-producing Bacteria from Marine Sediments Soil

Abstract

Screening of soil for antibiotics has been widely performed for about last 50 years and new antibiotics are still being found. This study was carried out during the period from March, 2011 to June, 2011 to screen and isolate antibiotic-producing bacteria from Red Sea sediments. Soil samples were collected in sterile plastic bag then cultured on nutrient agar supplemented with soil extract. Antibiotic- producing bacteria were detected by plate over-lay method using standard bacteria as indicator. Activity of antibiotic was evaluated against standard strains and clinical isolates using plate diffusion method. The result showed that 18 promising organisms were isolated. Of the most broad spectrum antibiotic-producers, one isolate was chosen and subsequently identified using biochemical tests as Bacillus thuringiensis. The product was found to be active against E. coli, Citrobacter sp. Salmonella typhi, Serritia marcescens and Pseudomonas aeruginosa in 4% glucose concentration. It is concluded that Red sea promising area for antibiotic producers. Further studies are required to validate this result.