Antibiotics are the secondary metabolites produced by bacteria and fungi to defend themselves from other pathogens. These secondary metabolites are being produced and used as a drug to cure different diseases. However, antibiotic resistance is a common problem that demands an urgent need to discover new antibiotics routinely. Several approaches have been performed to develop novel and potent antibiotics from natural sources against pathogenic bacteria. Among the different sources soil has been considered as the potent natural source of obtaining bacteria with the ability to produce noble antibiotics. The present work has been focused on the isolation of antibiotic producing bacteria from the soil samples collected from waste dumpsite. Among the 5 microbial isolates, 2 were shown to have inhibitory activities against Escherichia coli and Salmonella paratyphi. Morphological and biochemical tests revealed that both strains were Bacillus species with some differences in cultural characteristics. Molecular identification was performed by sequencing of the amplified 16S rRNA PCR products. The result showed that the two microbes were Bacillus subtilis and Bacillus cereus with 98% and 97% similarity score, respectively. This study suggests that Bacillus species have the potential to produce antibiotics against a broad spectrum of microbial growth and will be helpful in improving these strains for better production.
Key words: Antibiotic, Dumpsite soil, Bacteria, Bacillus, Phylogenetic