The solution contains 10000 units/mL of penicillin and 10000 µ g/mL of streptomycin. Antibiotics - penicillin and streptomycin have effective combined antibacterial effects on Gram positive and Gram negative bacteria, which can be used to prevent bacterial contamination in cell culture. Penicillin was initially purified from the fungus Penicillium, and its mechanism of action was to directly interfere with the synthesis of bacterial cell walls and indirectly alter cell walls by triggering enzyme release. Streptomycin was initially purified from Streptomyces griseus. Its mechanism of action is to bind to the 30S subunit of bacterial ribosomes, thereby inhibiting protein synthesis and leading to the death of sensitive bacteria.