Acid-dependent beta-lactam resistance in <i>Klebsiella pneumoniae</i> is mediated by paralogous class B PBPs and the class A PBP, PBP1b

susceptibility to beta-lactams at low pH. Altogether, these data emphasize the importance of functional redundancy among cell wall synthesis enzymes, which allows for specialization and ensures robust cell wall synthesis across a range of environmental conditions. IMPORTANCE: has a different repertoire of cell wall synthesis genes available than during growth at neutral pH due to the presence of acid-inducible paralogous copies of essential cell wall synthesis enzymes, PBP2 and PBP3. An additional functionally redundant enzyme, PBP1b, also contributes to acid-dependent beta-lactam resistance. Together, these findings expand our understanding of how bacteria maintain cell wall synthesis across diverse physicochemical environments and highlight potential new therapeutic targets.