Russian Journal of Biotechnology Articles archive Archive 2013 N 4 α-Acetolactate Oversynthesis from Glucose in a Diacetyl Producer Lactococcus lactis ssp. lactis bv. diacetylactis B2103, a Natural Mutant Deprived of α-Acetolactate Decarboxylase

α-Acetolactate Oversynthesis from Glucose in a Diacetyl Producer Lactococcus lactis ssp. lactis bv. diacetylactis B2103, a Natural Mutant Deprived of α-Acetolactate Decarboxylase

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

Страница: 24-38

 

α-Acetolactate Oversynthesis from Glucose in a Diacetyl Producer Lactococcus lactis ssp. lactis bv. diacetylactis B2103, a Natural Mutant Deprived of α-Acetolactate Decarboxylase

Biotekhnologiya, 2013, N 4, P. 24-38

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,  117545, Moscow Russia

e-mail:  glasunov@genetika.ru

 

The effect of oxygen supply rate on the activity of pyruvate metabolic pathways and their end products (lactate-dehydrogenase (LDH), pyruvate-formate-lyase (PFL), pyruvate-dehydrogenase (PDH) and acetolactate-synthase (ALS) pathways) in Lactococcus lactis ssp. lactis bv. diacetylactis B2103/74 strain has been investigated. In was found out that this culture, apart from inactivated α-acetolactate decarboxylase, possesses a unique natural capacity of oversynthesizing α-acetolactate (AL) up to 25—28 mM. The search for analogous strains in the diacetilicus bv. showed that this evidence is relatively infrequent; only one culture (VKPM 7590) was shown to have the same capacity. However, unlike the B2103/74 strain, the 7590 culture has an active α-acetolactate decarboxylase, and therefore, it is only able to produce acetoin. The oversynthesis of AL was observed at intense aeration (KLa ≥90—120 h–1); medium composition played a decisive role in the process. It was shown that a powerful shift of a part of the pyruvate flow from the LDH- to PDH- and ALS-pathway underlies the evidence of LA oversynthesis, and due a restricted throughout capacity of the PDH-pathway, all the metabolism of the additional pyruvate supplied from the LDH-pathway proceeded exclusively through the ALS- avoiding the PDH-pathway. The shift of the pyruvate metabolism from the LDH- to PDH- and ALS-pathways  in the B2103/74 culture is associated with the initiation of the oxidase reaction that reduces oxygen to H2O and therefore overshoots for this purpose NADH from LDH. The specific manifestation of this reaction in the B2103/74 and 7590 cultures that resulted in a deep rearrangement of all pyruvate metabolism for the production of α-acetolactate is owing to the occurrence of a superactive oxidase system that shifts 75—80% of the NADH flow from LDH to the oxidase pathway for NAD+ regeneration. The origin of this superoxidase system is unknown. It is suggested that it can be close in structure to a simplest membrane-built electron-transport chain.

 

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

 

The full English version of the article was published in “Applied Biochemistry and Microbiology”, 2014, Vol.50, Issue 7, pp. 689-700 as V. M. Serebrennikov, L. N. Kotova, A. V. Glazunov “α-Acetolactate overexpression from glucose in the diacetyl producer Lactococcus lactis ssp. lactis bv. diacetylactis B2103, a natural mutant lacking α-acetolactate decarboxylase”.

It is contained at the SpringerLink website:  http://link.springer.com/article/10.1134/S0003683814070059

DOI: 10.1134/S0003683814070059

 

02.04.2015, 1651 просмотр .

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