FIG. 4.

Spectra of in-situ kinetics of [2-¹³C]pyruvate and [1-¹³C]lactate cometabolism by resting cells of P. freudenreichii subsp. shermanii CIP 103027. Na [2-¹³C]pyruvate (194 μmol, corresponding to a final concentration of 67 mM in the NMR tube) and Na l-[1-¹³C]lactate (270 μmol, corresponding to a final concentration of 95 mM in the NMR tube) were added at time zero to a cell suspension (1 g [wet weight] in 2 ml of sterile saline water) at 24°C (297 K), and proton-decoupled ¹³C NMR spectra were collected every 104 s (64 scans). Chemical shifts were referred to an HMPA capillary. Only eight spectra, selected from 40 experiments, are presented. Abbreviations: Pyr C1, pyruvate C-1; Pyr C2 imp, C-2 of pyruvate hydrate; lact C2; lactate C-2. HMPA, hexamethylphosphoramide.