FIG. 2.

NMR spectra of end products formed from the cometabolism of [2-¹³C]glucose and [2-¹³C]acetate (40 mM each) by cell suspensions of l-LDH-deficient L. lactis at pH 5.5. (A) ¹³C NMR spectrum, acquired on a Bruker DRX500 spectrometer at 125.77 MHz with a quadruple nucleus probe head (spectral width, 30 kHz; pulse width, 13 μs; data points, 32K; repetition delay, 61.5 s; number of transients, 1,000). (B) ¹H NMR spectrum of the same sample analyzed after a 30-fold dilution in ²H₂O. Isotopomers of acetate and ethanol are indicated. The spectrum was acquired at 500.13 MHz with a 5-mm inverse detection probe head (spectral width, 8 kHz; pulse width, 6 μs; data points, 32K; repetition delay, 45 s). 2,3-BD, 2,3-butanediol.