IN-VIVO NUCLEAR-MAGNETIC-RESONANCE STUDY OF CITRATE METABOLISM IN PROPIONIBACTERIUM-FREUDENREICHII SUBSP SHERMANII

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