The screening of beta-lactamase inhibitors: inhibition by fatty acids produced by bacteria.

An active principle inhibiting beta-lactamases, which was found in the culture of a bacillus strain was a mixture of known C14-C17 fatty acids. The mixture was separated into five components by high-performance liquid chromatography. Among these components, 12-methyltetradecanoic acid showed the strongest activity (I50: 20-146 microM). The anteiso fatty acids having the 1-methylpropyl group exhibited an interesting activity inhibiting beta-lactamases.