Biosynthesis of α-Acetolactate in a Lactococcus lactis ssp. lactis biovar diacetylactis VKPM B2103 Natural Mutant Devoid of α-Acetolactate Decarboxylase depending on Medium Composition

Автор: V.M. Serebrennikov, L.N. Kotova, and A.V. Glazunov

Страница: 20-31

Biosynthesis of α-Acetolactate in a Lactococcus lactis ssp. lactis biovar diacetylactis VKPM B2103 Natural Mutant Devoid of α-Acetolactate Decarboxylase depending on Medium Composition

Biotekhnologiya, 2012, N 3, P. 20-31

UDC 577.151.52.547.442

Section:  “Producers, Biology, Selection, and Gene Engineering”

V.M. Serebrennikov ^*,  L.N. Kotova,  and  A.V. Glazunov ^*

The State Research Institute for Genetics and Selection of Industrial Microorganisms (GosNIIgenetika),  117545, Moscow Russia

e-mail:  glasunov@genetika.ru

The effect of yeast extract and peptones of different natures on the α-acetolactate and other final products of the pyruvate metabolism under the controlled conditions (pH and pO₂) of moderate aeration (K_La = 25 h^–1) by a Lactococcus lactis ssp. lactis biovar diacetylactis B2103 culture devoid of α-acetolactate decarboxylase has been investigated. Regardless of rather intense aeration, pO₂ rapidly decreased up to zero and a low residual O₂ concentration was maintained in the culture which corresponded to microaeration conditions. The latter were retained for some time in the culture even after the glucose exhaustion owing to the secondary metabolic pathways, and the biochemistry of these processes depended on the peptone nature. According to the obtained data, NADH-oxydase activity was the main factor through which yeast extract and peptones controlled the share of lactate in the final metabolites (homolact es cense) and their  accumulation. NADH-oxydase competed with lactate dehydrogenase for NADH, their common substrate, and therefore, restricting to some extent the pool of pyruvate as a substrate for lactate dehydrogenase, it redirected pyruvate through the other pathways including the α-acetolactate-synthase way. The elimination of yeast extract affected the pyruvate-dehydrogenase and pyruvate-formate-lyase pathways; as a result, the index of homolactes cense grew and the α-acetolactate synthesis was stimulated. Tryptone proved to be the most productive in respect of α-acetolactate accumulation (9—10 mM) among all the tested peptones which is probably first of all due to its capacity of inducing the highest NADH-oxydase activity.

Key words:  acetoin,  α-acetolactate,  citrate,  diacetyl,  lacticacid bacteria,  NADH-oxydase.

The full English version of the article was published in “Biotechnology in Russia”, 2012, Issue 3, pp. 20-31 as V. M. Serebrennikov, L. N. Kotova, A. V. Glazunov “Biosynthesis of α-Acetolactate in a Lactococcus lactis ssp. lactis biovar diacetylactis VKPM B2103 Natural Mutant Devoid of α-Acetolactate Decarboxylase depending on Medium Composition”.

It is contained at the Russian Scientific Electron Library website:  http://elibrary.ru/item.asp?id=21490723

25.05.2015, 1827 просмотров.