terclim by ICS banner
IVES 9 IVES Conference Series 9 CHANGES IN METABOLIC FLUXES UNDER LOW PH GROWTH CONDITIONS: CAN THE SLOWDOWN OF CITRATE CONSUMPTION IMPROVE OENOCOCCUS OENI ACID-TOLERANCE?

CHANGES IN METABOLIC FLUXES UNDER LOW PH GROWTH CONDITIONS: CAN THE SLOWDOWN OF CITRATE CONSUMPTION IMPROVE OENOCOCCUS OENI ACID-TOLERANCE?

Abstract

Oenococcus oeni is the main Lactic Acid Bacteria responsible for malolactic fermentation, converting malic acid into lactic acid and carbon dioxide in wines. Following the alcoholic fermentation, this second fermentation ensures a deacidification and remains essential for the release of aromatic notes and the improvement of microbial stability in many wines. Nevertheless, wine is a harsh environment for microbial growth, especially because of its low pH (between 2.9 and 3.6 depending on the type of wine) and nutrient deficiency. In order to maintain homeostasis and ensure viability, O. oeni possesses different cellular mechanisms including organic acid metabolisms which represent also the major pathway to synthetize energy in wine. Indeed, uptake and consumption of malate and citrate by this bacteria enables to activate a proton motive force (PMF) hence maintaining an intracellular pH by proton consumption1,2.

Citrate is found in wine at small concentrations (0.13 to 0.90 g/L). It can be metabolized by O. oeni into acetate, pyruvate and then aromatic compounds such as diacetyl, acetoin and 2,3-butanediol. The ability of citrate metabolism to activate the PMF could play a central role in the acid-tolerance of this bacterium. Nevertheless, a previous study has described an inhibition of O. oeni growth at low pH in presence of high amounts of citrate3. This toxic effect could come from the synthesis of one of the citrate metabolites as acetate.

In order to understand how citrate metabolism can be linked to acid tolerance of this bacterium, consumption of citrate was investigated in a great diversity of O. oeni strains. In addition, malate and sugar consumptions were also followed, as they can be impacted by citrate metabolism. These experiments enabled to draw metabolic fluxes in O. oeni according to the pH of the medium. In most cases, ma- late is first metabolized, then citrate and sugars, sequentially, proving that the priority is given to organic acid consumption at the expense of sugars in this bacterium. However, this experiment revealed different citrate consumption profiles which may be correlated to a greater or lesser acid tolerance according to the strain. Furthermore, a genomic comparison demonstrated the presence of mutations in the citrate operon of acid-tolerant industrial strains. Hence, acid tolerance could be linked to a change in the rate of citrate consumption in O. oeni.

 

1. Ramos, A., Poolman, B., Santos, H., Lolkema, J.S., Konings, W.N., 1994. Uniport of anionic citrate and proton consumption in ci-trate metabolism generates a proton motive force in Leuconostoc oenos. J. Bacteriol. 176, 4899–4905. https://doi.org/10.1128/jb.176.16.4899-4905.1994
2. Salema, M., Lolkema, J.S., Romão, M.V.S., Dias, M.C.L., 1996. The proton motive force generated in Leuconostoc oenos by L-malate fermentation. J. Bacteriol. 178, 3127–3132. https://doi.org/10.1128/jb.178.11.3127-3132.1996
3. Augagneur, Y., Ritt, J.-F., Linares, D.M., Remize, F., Tourdot-Maréchal, R., Garmyn, D., Guzzo, J., 2007. Dual effect of organic acids as a function of external pH in Oenococcus oeni. Arch. Microbiol. 188, 147–157. https://doi.org/10.1007/s00203-007-0230-0

DOI:

Publication date: February 9, 2024

Issue: OENO Macrowine 2023

Type: Article

Authors

Camille Eicher1, Joana Coulon2, Marion Favier2, Edouard Munier1, Thierry Tran1, Hervé Alexandre1, Cristina Reguant Miran-da3, Cosette Grandvalet1

1. UMR A. 02.102 Procédés Alimentaires et Microbiologiques, L’institut Agro Dijon, Université de Bourgogne Franche-Comté, Dijon, France
2. BioLaffort, Floirac, France
3. Departament de Bioquímica i Biotecnologia, Facultat d’Enologia, Universitat Rovira i Virgili, Tarragona, Spain

Contact the author*

Keywords

Oenococcus oeni, Citrate, Metabolic fluxes, Acid-tolerance

Tags

IVES Conference Series | oeno macrowine 2023 | oeno-macrowine

Citation

Related articles…

MONOSACCHARIDE COMPOSITION AND POLYSACCHARIDE FAMILIES OF LYOPHILISED EXTRACTS OBTAINED FROM POMACES OF DIFFERENT WHITE GRAPE VARIETIES

The recovery of bioactive compounds from grape and wine by-products is currently an important and necessary objective for sustainability. Grape pomace is one of the main by-products and is a rich source of some bioactive compounds such as polyphenols, polysaccharides, fatty acids, minerals and seed oil. Polysaccharides contained in the grape cell wall can be rhamnogalacturonans type II (RG-II), polysaccharides rich in arabinose and galactose (PRAG), mannoproteins (MP), homogalacturonans (HG) and non pectic polysaccharides (NPP).

Read More

OPTIMIZATION, VALIDATION AND APPLICATION OF THE EPR SPIN-TRAPPING TECHNIQUE TO THE DETECTION OF FREE RADICALS IN CHARDONNAY WINES

The aging potential of Burgundy chardonnay wines is considered as quality indicator. However, some of them exhibit higher oxidative sensitivity and premature oxidative aging symptoms, which are potentially induced by no-enzymatic oxidation such as Fenton-type reaction (Danilewicz, 2003). This chemical mechanism involves the action of transition metal, native phenolic compounds and oxygen which promote the generation of highly reactive oxygen species (ROS) such as hydroxyl radicals (OH) or 1-hydroxyethyl radicals (1-HER) from oxidation of ethanol. Such mechanism is involved in the radical oxidation occurring during bottle aging. According to Elias et al.,(2009a), the 1-HER is the most abundant radical in forced oxidation treated wines. Consequently, understanding its evolution kinetic in dry white wines is of great importance.

Read More

IMPACT OF MUST NITROGEN DEFICIENCY ON WHITE WINE COMPOSITION DEPENDING ON GRAPE VARIETY

Nitrogen (N) nutrition of the vineyard strongly influences the must and the wine compositions. Several chemical markers present in wine (i.e., proline, succinic acid, higher alcohols and phenolic compounds) have been proposed for the cultivar Chasselas, as indicators of N deficiency in the grape must at harvest [1]. Grape genetics potentially influences the impact of N deficiency on grape composition, as well as on the concentration of potential indicators in the wine. The goal of this study was to evaluate if the che- mical markers found in Chasselas wine can be extended for other white wines to indicate N deficiency in the grape must.

Read More

IMPACT OF METSCHNIKOWIA PULCHERRIMA DURING FERMENTATION ON AROMATIC PROFILE OF VIDAL BLANC ICEWINE

Non-Saccharomyces yeasts not only increase microbial diversity during wine fermentation, but also have a positive effect on improving wine aroma. Among these non-Saccharomyces yeast species, Metschnikowia pulcherrima is often studied and used in winemaking in recent years, but its application in icewine has been rarely reported. In this study, indigenous M. pulcherrima strains and Saccharomyces cerevisiae strains (commercial and indigenous strains) were sequentially inoculated for icewine fermentations; meanwhile, pure S. cerevisiae fermentations were used as the control; indigenous strains used above were screened from spontaneous fermentations of Vidal blanc icewine.

Read More

INFLUENCE OF THE THICKNESS OF OAK ALTERNATIVES ON THE COMPOSITION AND QUALITY OF RED WINES

Aging red wines in oak barrels is an expensive and laborious process that can only be applied to wines with a certain added value. For this reason, the use of oak alternatives coupled with micro-oxygenation has progressively increased over recent years, because it can reproduce the processes taking place in the barrels more economically and quickly [1]. Several studies have explored how oak alternatives [2-5] can contribute to wine composition and quality but little is known about the influence of their thickness.

Read More