Antibacterial Potential of Ethyl-Acetate Extracts of Marine Streptomyces spp. AIAH-10 against Drug Resistant Escherichia coli

The rapid increase in drug resistance among bacteria is a public health challenge in the 21st century. To combat drug resistance, searching for new broad-spectrum antibiotics is urgent and marine microbial flora may be a potential source. The present study was designed to isolate marine actinomycetes strains (AIAH-01 to AIAH-29) from the soil sediments of different locations of the sundarbans mangrove forest, Bangladesh by serial dilution method. Primary screening of antimicrobial activity was performed by cross plate technique and AIAH-10 was undertaken for further analysis due to its potential activity against a number of pathogenic bacteria. On the basis of morphological, cultural, biochemical and cell composition analysis, AIAH-10 belonged to Streptomyces spp. Secondary metabolites of AIAH-10 exhibited significant activity (with zone sizes of 15 mm and 12 mm) against ciprofloxacin and azithromycin induced resistant Escherichia coli (E. coli) respectively (50 μg extracts/disc). Minimum inhibitory concentration (MIC) of extracts against ciprofloxacin and azithromycin induced resistant E. coli was found to be 16 and 32 μg/ml respectively. Time-kill profile of the extracts also revealed its considerable antimicrobial activity. Therefore it may be concluded that the marine Streptomyces spp. AIAH-10 isolated from the sundarbans mangrove forest, Bangladesh produces bioactive compounds that can be applied against resistant and multi-drug resistant pathogens.