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Extracellular Polysaccharide From Marine Streptomyces sp. KAR3: Structural Characterization, Antibacterial, and
Karthick Kumar S B1, Rajkumar Prabhakaran2,3, Rajkumar Manickam3,4
1Department of Microbiology, Karpagam Academy of Higher Education, Eachanari, Coimbatore, Tamil Nadu, India.
Biotechnology and Applied Biochemistry
|August 10, 2026
Summary
Marine bacteria yield novel extracellular polysaccharides (EPS) with significant antibacterial and anticancer properties. This study highlights EPS from Streptomyces geysiriensis as a promising natural compound for biomedical applications.
Area of Science:
- Marine microbiology
- Biochemistry
- Pharmacology
Background:
- Marine environments are rich sources of bioactive natural products.
- Extracellular polysaccharides (EPS) from marine bacteria show potential for biomedical applications.
- Streptomyces species are known producers of diverse bioactive compounds.
Purpose of the Study:
- To isolate and characterize a marine Streptomyces sp. strain.
- To evaluate the antibacterial, antibiofilm, and anticancer activities of the isolated EPS.
- To optimize EPS production and elucidate its structural properties.
Main Methods:
- Isolation and identification of marine Streptomyces sp. strain KAR3 using biochemical tests and 16S rRNA gene sequencing.
- Optimization of EPS production and structural characterization using UV spectroscopy, FTIR, NMR, and GC-MS.
- In vitro evaluation of antibacterial activity against Gram-positive and Gram-negative bacteria, antibiofilm activity, and cytotoxicity against MDA-MB-231 cancer cells.
Main Results:
- Strain KAR3 identified as Streptomyces geysiriensis, producing 4.4 g/L EPS.
- FTIR, NMR, and GC-MS analyses confirmed the EPS as a complex polysaccharide primarily composed of glucose.
- The EPS demonstrated dose-dependent antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, and Enterococcus faecalis, with MIC at 100 µg/mL.
- Significant antibiofilm activity was observed.
- The EPS exhibited strong cytotoxicity against MDA-MB-231 cancer cells with an IC50 value of 25.44 µg/mL.
Conclusions:
- Marine Streptomyces geysiriensis strain KAR3 produces a complex EPS with broad-spectrum antibacterial and antibiofilm activities.
- The marine EPS shows significant potential as a cytotoxic agent against breast cancer cells (MDA-MB-231).
- This study underscores the potential of marine-derived EPS as a valuable source for developing new antimicrobial and anticancer therapeutics.
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