passages.id: split_1_test_500_passage
passages.type: progene_text
passages.text: Furthermore , when both PBPs 2 and 3 were inactivated by the beta-lactams mecillinam and aztreonam , respectively , several mutants did not lyse but continued to grow as enlarged spheres , so that one mutant synthesized osmotically resistant peptidoglycan when only 2 of 12 PBPs ( PBPs 1b and 1c ) remained active .