Abstract

Aims: Streptomyces spp. are the major producers of antibiotics and antimicrobial compounds. We have previously isolated a novel Streptomyces sp. strain INACH3013a from Ardley Island in Antarctica, exhibiting antibacterial activity against several Gram-negative and Gram-positive test pathogens. However, the test pathogens used previously were limited and the effectiveness of the intracellular and extracellular bioactive compounds and the number of compounds with antibacterial properties is still relatively unknown. Hence, this study was aimed to extract the intracellular and extracellular bioactive compounds and evaluate their effectiveness against various pathogens' strains. Methodology and results: Metabolites of Streptomyces sp. strain INACH3013a were extracted using dichloromethane (DCM) and tested against 18 Gram-positive or Gram-negative pathogens. Minimum inhibitory concentration (MIC) of bioactive substances was determined, and the bioactive compounds were separated via thin layer chromatography (TLC). The MIC of INACH3013a's metabolites against Staphylococcus aureus ATCC 33591 was 2.5 mu g/mu L. Antimicrobial activity of the compounds separated by the TLC, with Rf values of 0.87 and 0.81 for the extracellular and intracellular bioactive compounds, respectively, were assayed. The intracellular metabolites exhibited antimicrobial activity against Escherichia coli ATCC 35218, with MIC of 100 mu g/mu L. Conclusion, significance and impact of study: This study examines the inhibition of Gram-positive and Gramnegative bacteria by Streptomyces sp. strain INACH3013a. INACH3013a produced effective antibacterial compounds with the potential for new antibiotics against resistant bacterial strains.