METABOLIC BEHAVIOR OF LACTOCOCCUS-LACTIS IN RESPONSE TO ENVIRONMENTAL-CONDITIONS

Growth and metabolism of the lactic acid bacteria are closely dependen t on the nutritional environment. Major environmental constraints, whe n they are not directly related to the bacterial growth, are the natur e and the availability of the nitrogen and carbon sources. In this pap er, 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 devel oped and was successively tested in other nutritional environments. Th is model differs from that generally assumed for lactic acid bacteria and can be applied to other lactococci. Fructose-1,6-bisphosphate play s 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 t he role of serine utilization on the metabolism of L. lactis NCDO 2118 was investigated in more detail. (C) Inra/Elsevier, Paris.