Metal-β-lactamase is a zinc-dependent enzyme produced by certain bacteria, such as Pseudomonas aeruginosa and Acinetobacter baumannii, that hydrolyzes β-lactam antibiotics, including penicillins, cephalosporins, and carbapenems, thereby conferring antibiotic resistance. This reagent, typically supplied as a freeze-dried powder, is used in microbiological research to study resistance mechanisms, screen for novel β-lactamase inhibitors, and develop strategies to combat multidrug-resistant infections. It is essential in assays evaluating antibiotic efficacy and in the discovery of new antimicrobial agents to address emerging resistance challenges in clinical settings.