The chemolithotroph, Hydrogenomonas eutropha, was tested for its ability to utilize a variety of single nitrogen sources during growth in an atmosphere of Hz-Oz-C02.
The present data show that H . eutropha can utilize the nitrogen from many, but not all, amino acids, several sulfur-containing amino acids, glucosamine, and two aliphatic amides. The nitrogen concentration that supported maximum growth for NH,Cl, L-glutamate, L-glutamine, urea, and glycine was in the 0.010-0.019M range. H . eutropha failed to remove the nitrogen from primary and secondary amines, cycloleucine, tert-DL-leucine, DL-p-fluorophenylalanine, ~~-5-methyltryptophan, creatine, and creatinine. This microorganism was able to partially degrade at least six substituted indoles and/or tryptophan catabolites and six substituted imidazoles and/or histidine catabolites. All of a series of 17 dipeptides were able to serve as a nitrogen source for growth in the absence of NHaC1. Extracts of H . eutropha were able to catalyze the hydrolysis of 16 a-dipeptides, 2 tripetides, a tetrapeptide, a polypeptide, a p-aspartyl peptide, 2 7-glutamyl peptides, a N-acetyl amino acid, and 4 amino acid amides. These results emphasize the effectiveness of H . eutropha in utilizing a wide diversity of organic nitrogenous compounds containing amino and amide groups, heterocyclic rings, and peptide bonds.