Comportement métabolique de Lactococcus lactis en réponse à l'environnement

Metabolic behavlour of Lactococcus lactis in response to environmental conditions. Growth and metabolism of the lactic acid bacteria are closely dependent on the nutritional environment. Major environ mental constraints, when they are not directly related to the bacterial growth, are the nature and the availability of the nitrogen and carbon sources. ln this paper, the influence of the carbon substrate (sugar) on the metabolism of Lactococcus lactis NCDO 2118 was studied from a kinetic and enzymatic point of view. An original model of metabolism control has been developed and was successively tesied in other nutritional environments. This model differs from that generally assumed for lactic acid bacteria and can be applied to other lactococci. Fructose-J.o-bisphosphate plays only a minor role in controlling the further metabolism of pyruvate and NADH/NAD ratio exerts the major control over glycolytic flux. The metabolic consequences of co-substrate utilization were analyzed and the role of serine utilization on the metabolism of L. lactis NCDO 2118 was investigated in more detail. © Inra/Elsevier, Paris. Lactococcus lactis / growth / homolactic and mixed metabolism / co-substrate