COMETABOLISM SUGAR-AMINO ACIDS IN LACTOCO CCUS-LACTIS

The growth of Lactococcus lactis subsp. lactis NCDO 2118 was directly related to the medium composition as regards both the growth yield and the growth rate. The growth yield relative to the catabolic substrate , glucose, and the maximun specific growth rate increased with the med ium complexity. Growth was limited by the cells' capacity to feed the anabolic pathways, while the catabolic rate was always proportional to the anabolic rate thereby avoiding energy spoilage. The conversion yi eld of glucose to fermentation products was constant whatever the medi um composition. Approximately 88% of the glucose was recovered as clas sical fermentation products and, in a minimal medium containing 6 amin o acids, a further 5% in biomass accounting for 60% of the total bioma ss. Inversely, some of the amino acids were converted to fermentation products. (C) Inra/Elsevier, Paris.