NMR scans of the E. coli RR1 pta ldhA double mutant (A) and the recombinant strain harboring plasmid pLS65 (l-LDH) (B). Cultures were incubated anaerobically in minimal medium supplemented with glucose and auxotrophic amino acids, including proline and leucine. Abbreviations: A, acetate; E, ethanol; L, lactate; P, pyruvate; S, succinate.