Potential Bioactive Compounds from Marine Streptomyces sp. and Their In Vitro Antibiofilm and Antibacterial Activities Against Antimicrobial-Resistant Clinical Pathogens

Antimicrobial resistance issues have risen dramatically in recent years, posing a severe concern to humans worldwide. The urgent need to find novel compounds for pharmaceutical applications prompts the research of under-explored environments such as marine ecosystems. The present study was designed to discover novel secondary metabolites, and we have isolated about 30 actinomycetes from the marine soil samples collected in Thondi (Ramanathapuram, Tamil Nadu, India), where most isolates are associated with the genus Streptomyces. Out of 30, one potentially active strain (Streptomyces sp. SRMA3) was identified using primary and secondary screening methods against the drug-resistant clinical pathogens. The active metabolites extracted from the selected active isolate were subjected to partial purification and characterization using Fourier transform infrared spectrophotometer (FTIR) and gas chromatography-mass spectroscopy (GC-MS) analysis. The minimum inhibitory concentration (MIC) value was determined for the active metabolite. Further, the partially purified active fraction was revealed for its antibacterial and antibiofilm activity against drug-resistant clinical pathogens. Light and fluorescence microscopy detected the viability and adhesion of the biofilm-forming drug-resistant pathogens. Growth curve analysis showed that the active metabolite has the potential to inhibit drug-resistant pathogens. The synergistic effect of active metabolite with commercial antibiotics also revealed that it could enhance the activity of antibiotics in antimicrobial resistance pathogens. This study shows that the isolated Streptomyces sp. SRMA3 is a potentially active strain, and the metabolite derived from this strain has a good antibacterial and antibiofilm activity against antimicrobially resistant clinical pathogens and could be used for various biotechnological applications.