GLUCOSE-METABOLISM AND INTERNAL PH OF LACTOCOCCUS-LACTIS SUBSP LACTISCELLS UTILIZING NMR-SPECTROSCOPY

The metabolism of glucose was studied in Lactococcus lactis subsp. lac tis CNRZ 125 by C-13 NMR. The initial rate of glucose utilization was higher for exponential phase cells than for stationary phase cells [15 0 vs 85 nmol g (dry wt)(-1) s(-1)]. P-31 NMR was used to determine cha nges in glycolytic phosphorylated intermediates (fructose-1,6-diphosph ate, dihydroxyacetone phosphate and phosphoglycerate). The internal pH s of L. lactis subsp. lactis CNRZ 141 and CNRZ 125 were also measured by P-31 NMR as a function of the external pH during growth. When the e xternal pH was 6.8, the internal pHs of strain CNRZ 141 and CNRZ 125 w ere similar, 7.4. After the external pH had decreased to 5.5, the inte rnal pH of strain CNRZ 141 had declined by 0.6 unit, whereas that of s train CNRZ 125 had decreased by only 0.2 unit of pH.