Distribution of beta-lactam and beta-lactone producing bacteria in nature.

Over one million bacteria were isolated from a large variety of soil, plant and water samples collected from different environments and examined in an extremely sensitive and highly specific screen for beta-lactam production. A group of seven related monocyclic beta-lactams (monobactams) were isolated from strains representing four genera-Agrobacterium, Chromobacterium, Gluconobacter and Pseudomonas. Monobactam-producing strains of Agrobacterium and Pseudomonas were isolated only rarely. Producing strains of Chromobacterium were isolated from a relatively limited number of habitats while the Gluconobacter strains appeared to be widespread in nature. In addition, three closely related beta-lactone-containing molecules were isolated from strains representing three genera-Arthrobacter, Bacillus and Pseudomonas. The Bacillus and Pseudomonas strains were isolated infrequently but from a variety of samples. The producing strain of Arthrobacter was isolated only once.