In vivo nuclear magnetic resonance study of citrate metabolism in Propionibacterium freudenreichii subsp. shermanii

Citrate metabolism by resting cells of Propionibacterium freudenreichii subsp, shermanii was investigated. ln vivo C-13 nuclear magnetic resonance spectroscopy was used to study the pathway of citrate breakdown and to probe its utilization, non-invasively, in living cell suspensions, [2,4-C-13]citrate was metabolized by resting cells to glutamate labelled in positions 2 and 4. In the presence of lactate or pyruvate, its rate of consumption was faster, but it was still converted to glutamate. No catabolic pathway other than the first third of a turn of the tricarboxylic acid cycle was used by Prop. freudenreichii subsp. shermanii to degrade citrate.