Carbenicillin is a semi-synthetic carboxypenicillin that is effective mostly against Gram-negative bacteria. Carbenicillin is very similar to ampicillin, however the breakdown byproducts of beta-lactamase enzymatic reaction are typically less toxic than ampicillin. It is more stable and resistant to beta-lactamase than ampicillin. It is widely used for plant cell culture selection due to economic reasons.  Carbenicillin can be used with Vancomycin Hydrochloride to maintance the plant cell culture after selection due to its low toxicity to the plant cells.