Inhibitor of bacterial cell wall synthesis resulting in lysis or deformation of the bacterium. Inhibits crosslinking of peptidoglycan by binding and inactivating transpeptidases. Highly active against gram negative bacteria. B-Lactamase sensitive. Plant cell culture tested. Widely used as a selective agent for transformation of plasmid encoding for b-Lactamase production such as pBR322 or pUC (Ampr).