Diacetyl production mechanism by a strain of Lactococcus lactis spp. lactis bv. diacetylactis. Study of alpha-acetolactic acid extracellular accumulation under anaerobiosis.
Diacetyl production via alpha-acetolactic acid (ALA) extracellular decarboxylation in Lactococcus lactis spp. lactis bv. diacetylactis SD 933 cultures has been assessed under anaerobiosis both in batch and continuous fermentations at pH 5.5 and 8.0 by studying the effects of alpha-acetolactate decarboxylase (ADC) addition in the culture broth. This enzyme, favoring the formation of acetoin instead of diacetyl, was added extracellularly and did not disturb diacetyl production. Moreover, oxidation experiments on extracellular culture media did not reveal any increase in diacetyl amount caused by extracellular ALA oxidative decarboxylation. These observations confirm previous assertions concerning the mechanism and localization of diacetyl synthesis by the SD 933 strain.
Laboratoire des Sciences du Génie Chimique/C.N.R.S., U.P.R. 6811, P. R. A. B. I. L., 13 rue de Bois de la Champelle, F-54500, Vandoeuvre-lès-Nancy, France.
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Rondags
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Halliday
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Marc