Amino Acid Metabolism in the Genus Propionibacterium 1

Abstract

Summary

Propionibacterium shermanii, P. arabinosum, and P. pentosaceum can synthesize many amino acids as determined by growth in the absence of a single amino acid or a group of biosynthetically related amino acids. P. shermanii and P. arabinosum were distinctive in their limited ability to synthesize glutamate and aspartate. When examining amino acids and (NH₄)₂SO₄ as possible single nitrogen sources, P. shermanii had the most limited capacity and grew only on glutamate. P. arabinosum was able to utilize several amino acids, but not (NH₄)₂SO₄, as the main nitrogen source. For P. pentosaceum, glutamate dehydrogenase was demonstrated for the function of ammonia assimilation, l-serine dehydratase for l-serine degradation, and an AMP- or ADP-dependent l-threonine dehyratase for threonine catabolism. A biosynthetic, l-isoleucine-inhibited, l-threonine dehydratase was observed in P. pentosaceum.