A DESCRIPTIVE MODEL FOR CITRATE UTILIZATION BY LACTOCOCCUS-LACTIS SSP LACTIS BV DIACETYLACTIS

A model for the use of citrate by Lactococcus lactis ssp lactis bv diacetylactis CNRZ 125 is proposed. Citrate metabolism by this strain leads to the production of acetate, CO2 and C4 compounds (diacetyl, acetoin, 2,3-butylene glycol). The model furnishes correct simulations, consistent with published results on the pathways used and on lactose-citrate co-metabolism. Citric acid is incorporated independently of growth. The production of flavoring compounds is a complex process, depending on the rate of citrate utilization, on the proportion of pyruvate arising from citrate and which condenses to form alpha-acetolactate and CO2, on the rate of transformation of alpha-acetolactate to diacetyl and acetoin, as well as on the rate of reduction of these compounds to 2,3-butylene glycol.