C-13 NUCLEAR-MAGNETIC-RESONANCE STUDIES OF GLUCOSE-METABOLISM IN L-GLUTAMIC ACID AND L-LYSINE FERMENTATION BY CORYNEBACTERIUM-GLUTAMICUM

Glucose metabolism in Corynebacterium glutamicum was investigated using C-13 nuclear magnetic resonance (C-13 NMR) spectroscopy. L-Glutamic acid and L-lysine producers were cultivated in medium containing [1-C-13]- or [6-C-13]glucose, and the C-13 NMR spectrum of the culture filtrate was measured. In each fermentation, the ratio of the contributions of the Embden-Meyerhof pathway (EMP) and the hexosemonophosphate pathway (HMP) (EMP/HMP) was calculated on the basis of the C-13 population at each carbon in the products. The EMP/HMP was estimated as 80/20 in glutamic acid fermentation; in contrast, it was 30-40/60-70 in lysine fermentation. These results indicate that HMP contributes much more in lysine fermentation, probably because of the greater requirement of NADPH in lysine formation from glucose.