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

Article Abstract:

Researchers have succeeded in creating a mutant of Lactococcus lactis subsp. lactis biovar diacetylactis that can produce excess quantities of alpha-acetolactate, which is an industrial flavoring compound. The mutants lack alpha-acetolactate dehydrogenase and also have low lactate dehydrogenase activity.

Flavoring essences, Flavorings, Industrial microorganisms

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Effect of initial oxygen concentration on diacetyl and acetoin production by Lactococcus lactis subsp. lactis biovar diacetylactis

Article Abstract:

Aroma compounds (acetoin and diacetyl) are produced by Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 in fresh unripened cheese at different initial oxygen concentrations (0, 21, 50 and 100% of the medium saturation by oxygen). These compounds are produced in maximum number only after all the citrate is consumed. The quantity of diacetyl and acetoin produced by L. lactis increases in the presence of oxygen.

Oxygen, Distribution, Aromatic compounds

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Isolation and properties of Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 mutants producing diacetyl and acetoin from glucose

Article Abstract:

Three mutants of Lactococcus lactis subsp. lactis biovar diacetylactis CNRZ 483 that produced diacetyl and acetoin from glucose were isolated after treatment with the mutagen N-methyl-N'-nitro-N-nitrosoguanidine. The lactate dehydrogenase activity of these mutants were substantially reduced and the mutants produced less lactate than the parental strain. The kinetic characteristics of lactate dehydrogenase of strain CNRZ 483 and the mutants indicated differences in the affinity of the enzyme for pyruvate, NADH and fructose-1,6-diphosphate.

Milk, Dairy bacteriology

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