As a part of the penicillin antibiotic class, carbenicillin is effective against several Gram-negative bacteria, including Escherichia coli and Pseudomonas aeruginosa. Carbenicillin inhibits bacterial cell-wall synthesis by inactivating transpeptidases on the inner surface of the bacterial cell membrane. In molecular biology, it is useful in removing non-transformed cells from cultures, ensuring that only cells that have successfully taken up the desired plasmid vectors are retained.