Studies in Valine Biosynthesis VIII. Dihydroxyacid Dehydratase Activity in Microorganisms with Diverse Fermentation Patterns

Amino Acid Metabolism in the Genus Propionibacterium

“…Since Propionibacterium shermanii, Propionibacterium arabinosum, and Propionibacterium pentosaceum possessed a reductoisomerase and a dihydroxyacid dehydratase, it was concluded that the parallel pathway of biosynthesis of these two amino acids from pyruvate and a-ketobutyrate, re-1 P a r t of the data in this paper is from the thesis submitted to the Graduate School, University of spectively, was present here as in Escherichia roli ( 6 ) . During this investigation, the paucity of information on the amino acid metabolism of these bacteria became apparent and required ascertaining their simplest defined medium.…”

“…Knowledge of these distinctive characteristics led to our earlier experimental inquiry on the identity of the pathway of valine-isoleucine biosynthesis in the genus Propionibacterium (6). Since Propionibacterium shermanii, Propionibacterium arabinosum, and Propionibacterium pentosaceum possessed a reductoisomerase and a dihydroxyacid dehydratase, it was concluded that the parallel pathway of biosynthesis of these two amino acids from pyruvate and a-ketobutyrate, re-1 P a r t of the data in this paper is from the thesis submitted to the Graduate School, University of spectively, was present here as in Escherichia roli ( 6 ) .…”

“…For larger scale growth, the propionic acid bacteria were incubated at 30" semiaerobically in 1 liter of medium in a plugged 2-liter Erlenmeyer flask. After 24 to 48 hr incubation at SO0, the log phase cells were harvested by centrifugation at 3,500g for 15 min at The time for maximum release (i.e., highest specific activity) for another enzyme from P. pentosaceum, P. sherrnanii, and P. arabinosum was 10, 5 and 5 min, respectively ( 6 ) ; these sonicatioii times were used in the present study. The ruptured cell suspension was centrifuged at 18,OOOg or 39,OOOg for 20 min at 3" as specified below.…”