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.
