Utilization of Cyclic Amides and Formation of ω-Amino Acids by Microorganisms

Abstract

In investigations on the utilization of cyclic amides by microorganisms, Noe and Nickerson (J. Bacteriol. 75:674, 1958) studied the metabolism of y-butyrolactam by Pseudomonas aeru-ginosa, and Kato and Fukumura (Chem. Ind. [London], p. 1146, 1962) reported on the bacterial breakdown of E-caprolactam. But the formation of w-amino acids, hydrolytic products of these cyclic amides, was not detected in either case. To determine the occurrence of "cyclic amide hydrolase," we screened a number of microorganisms utilizing the cyclic amides (y-butyro-lactam, 6-valerolactam, E-caprolactam, and pyroglutamic acid) for the production of co-amino acids. The media contained 0.1% glucose, 0.05% sodium citrate, 0.7% K2HPO4, 0.2% KH2PO4, 0.01% MgSO4-7H20, and the cyclic amide as the sole source of nitrogen. The utilization of cyclic amides was measured by growth of the microorganism , and the formation of w-amino acids was detected by paper chromatography of the broth. In the medium containing 0.2% L-pyroglutamic acid, 46 strains of bacteria (Pseudomonas, Achro-mobacter, Serratia, and Proteus species), 13 strains of streptomyces, 27 strains of molds, and 4 strains of yeasts, such as Hansenula, Pichia, Saccharomyces and Torula, utilized the acid for their growth. However, accumulation of glutamic acid in the culture broth was not observed. In the medium containing y-butyrolactam, 6-valerolactam, and E-caprolactam at a final concentration of 0.1 %, 32 strains of bacteria, 3 strains of streptomyces, 28 strains of molds, and 2 strains of yeast grew satisfactorily. Among these microorganisms, 7 strains of Pseudomonas, Mycobacterium smegmatis, and Nocardia asteroides accumulated w-amino acids in the broth. To determine which lactam was most readily utilized for growth, experiments were carried out with media S-5, S-6, and S-7, containing 'y-butyrolactam, 6-valerolactam, and E-caprolactam,