COMPARISON OF ALPHA-ACETOLACTATE SYNTHASE AND ALPHA-ACETOLACTATE DECARBOXYLASE IN LACTOCOCCUS SPP AND LEUCONOSTOC SPP

Cell-free extracts of Leuconostoc and Lactococcus species were tested for their alpha-acetolactate synthase and alpha-acetolactate decarboxy lase activities. In Leuconostoc mesenteroides subsp. cremoris, Leucono stoc mesenteroides subsp. mesenteroides and Leuconostoc lactis, the Km of alpha-acetolactate synthase for pyruvate was close to 10 mM wherea s it was 30 mM in Lactococcus lactis subsp. lactis biovar. diacetylact is. The Km of alpha-acetolactate decarboxylase for alpha-acetolactic a cid was very low (0.3 mM) in Leuconostoc species in comparison to Lact ococcus lactis subsp. lactis biovar. diacetylactis (60 mM). In the lat ter bacterium, alpha-acetolactate decarboxylase showed a sigmoidal dep endance upon alpha-acetolactic acid and was activated by the three bra nched-chain amino acids: leucine, isoleucine and valine.