- Streptomycin is an aminoglycoside antibiotic widely used in cell culture to prevent bacterial contamination, especially from Gram-negative organisms. It is frequently combined with penicillin to create a broad-spectrum antimicrobial cocktail known as Pen-Strep, which is included in many commercially available culture media. Streptomycin exerts its antibacterial effect by binding to the 30S subunit of the bacterial ribosome, thereby inhibiting protein synthesis. This leads to misreading of mRNA and production of nonfunctional or toxic proteins, ultimately resulting in bacterial cell death.
- Unlike penicillin, which is effective primarily against Gram-positive bacteria, streptomycin is particularly potent against aerobic Gram-negative bacteria, making the two drugs highly complementary in mixed-use. It is especially useful during the establishment of primary cell cultures from tissues that may harbor a wide range of microbial contaminants. The typical working concentration of streptomycin in cell culture is 50–100 µg/mL.
- Streptomycin is generally well tolerated by mammalian cells, but prolonged or excessive use can pose risks. Overuse may select for resistant bacterial strains or mask inadequate aseptic practices in the laboratory. Additionally, while streptomycin targets bacterial ribosomes, it shares some structural similarity with mitochondrial ribosomes in eukaryotic cells, raising concerns—especially at high concentrations—about potential off-target effects on mitochondrial protein synthesis. However, under normal culture conditions and concentrations, such effects are minimal or negligible.
- Streptomycin is stable in aqueous solutions when stored appropriately, usually at 4°C for short-term use or –20°C for long-term storage. As with all antibiotics in culture, its inclusion should be based on necessity and proper risk assessment rather than routine use. It is most valuable during initial cell isolation, recovery from contamination, or when working in environments with high risk of exposure to bacterial pathogens.
