beta-lactam biosynthesis cephalosporin biosynthesis pathway UPa:UPA00475 Biosynthesis of cephalosporins, a class of beta-lactam antibiotics. Together with cephamycins they belong to a sub-group called cephems. Cephalosporins are bactericidal and have the same mode of action as other beta-lactam antibiotics (such as penicillins). Cephalosporins disrupt the synthesis of the peptidoglycan layer of bacterial cell walls. The final transpeptidation step in the synthesis of the peptidoglycan is facilitated by transpeptidases known as penicillin binding proteins (PBPs). PMID:15719551 PMID:15719553 GO:0043646