Diacetyl and alpha-acetolactate overproduction by Lactococcus lactis subsp. lactis biovar diacetylactis mutants that are deficient in alpha-acetolactate decarboxylase and have a low lactate dehydrogenase activity.

C Monnet, F Aymes, G Corrieu

Index: Appl. Environ. Microbiol. 66(12) , 5518-20, (2000)

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Abstract

Lactococcus lactis subsp. lactis biovar diacetylactis strains are utilized in several industrial processes for producing the flavoring compound diacetyl or its precursor alpha-acetolactate. Using random mutagenesis with nitrosoguanidine, we selected mutants that were deficient in alpha-acetolactate decarboxylase and had low lactate dehydrogenase activity. The mutants produced large amounts of alpha-acetolactate in anaerobic milk cultures but not in aerobic cultures, except when the medium was supplemented with catalase, yeast extract, or hemoglobin.