Penicillin/Streptomycin (Pen/Strep) is a penicillin and streptomycin antibiotic combination that is ready to use. It may be included in cell culture medium and is frequently used in cell culture.
Gram-positive and gram-negative bacterial contamination can be successfully treated with penicillin/streptomycin. It comes in the form of a 100x concentration. Penicillins, which are members of the -lactam family, work by blocking an enzyme necessary for the creation of new membrane components (D-Alanin-Transpeptidase).
Therefore, penicillin only works on cells that are actively dividing. Streptomycin, on the other hand, works by attaching to the bacterial ribosome’s 30S subunit. Whether or not the cell is actively dividing, this process prevents the bacteria from producing proteins.