PenStrep

Penicillin-streptomycin, or Pen/Strep, is a combination of penicillin G and streptomycin. This solution is widely used in the culture medium for mammalian cells to prevent bacterial contamination.

The solution contains 10,000 units of penicillin G (sodium salt) and 10,000 micrograms of streptomycin (sulfate) per milliliter. These antibiotics act synergistically to inhibit bacterial growth and maintain a sterile environment during cell culture. However, the common practice is to use Pen/Strep for initial cultures or to protect valuable cell stocks.

Researchers typically add 0.5 to 1 milliliter of Pen/Strep solution to 100 milliliters of cell culture medium, resulting in a final concentration of 50 to 100 international units per milliliter of penicillin and 50 to 100 micrograms per milliliter of streptomycin.