Ultrasonic disintegration of bacteria may lead to irreversible inactivation of beta-lactamase.

When ultrasonic disintegration of bacteria was employed to liberate intracellular beta-lactamases there was rapid and irreversible inactivation of the type-Id beta-lactamase from Pseudomonas aeruginosa. Various type-V beta-lactamases (PSE-2, 3 and 4) from P. aeruginosa, as well as Enterobacter cloacae type-Ia beta-lactamase were much less affected by sonication. None of the beta-lactamases was inactivated by French Press disruption. We suggest that French Press disruption should be the method of choice for the release of beta-lactamases, unless the enzyme in question is known to be unaffected by ultrasonic treatment.