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…

FACTORS AFFECTING QUERCETIN SOLUBILITY IN SANGIOVESE RED WINE: FIRST RESULTS

Quercetin (Q) is present in grape in form of glycosides and as aglycone. These compounds are extracted from grape skins during winemaking. In wines, following the hydrolysis reactions, the amount of quercetin aglycon can exceed its solubility value. Unfortunately, a threshold solubility concentration for quercetin in wine is not easy to determine because it depends on wine matrix (Gambuti et al., 2020).

Read More

Managing changes in taste: lessons from champagne in britain 1800-1914

This paper focuses on how taste in wine (and other foods) changes and the implications of this process
for producers and merchants.
It draws primarily on the changing taste of and taste for champagne in Britain in the 19th century. Between 1850 and 1880 champagne went from a dosage level of around 20% (20 grams sugar / litre) to 0%. Champagne became the ‘dinner wine of the elite – drunk with roast meat and savoury dishes.
Contemporaries accepted that while most people could distinguish the taste of good champagne from that of bad, very few could distinguish very good from good.

Read More

THE EFFECT OF COPPER ON THE PRODUCTION OF VARIETAL THIOLS DURING THE ALCOHOLIC FERMENTATION OF COLOMBARD AND GROS MANSENG GRAPE JUICES

Nowadays, the rapid growth of vineyards with organic practices and the use of copper as the only fun-gicide against downy mildew raises again the question of the effect of copper on varietal thiols in wine, especially 3-sulfanylhexan-1-ol (3SH) and its acetate (3SHA). A few decades ago, several works indicated that the use of copper in the vineyard had a negative effect on the content of varietal thiols in Sauvignon blanc wines [1, 2]. However, these studies only considered the concentration of the reduced form (RSH) of varietal thiols, without quantifying the oxidised ones. For this purpose, we proposed to monitor both reduced and oxidised forms of varietal thiols in wine under copper stress during alcoholic fermentation to have a more complete picture of the biological and chemical mechanisms.

Read More

WINE RACKING IN THE WINERY AND THE USE OF INERT GASES: CONTROL AND OPTIMIZATION OF THE PROCESS

Atmospheric oxygen (O₂) generates oxidation in wines that affect their physicochemical and sensory evolution. The O₂ uptake in the different winemaking processes is generally considered to be negative for the sensory characteristics of white and rosé wines. Wine racking is a critical point of O₂ uptake, as the large surface area of the wine exposed during this operation and the inability to maintain an effective inert gas blanket over it.
The aim was to study the uptake of O₂ during the racking of a model wine as a reference and to compare with purging the destination tank with different inert gases.

Read More

ENRICHMENT OF THE OENOLOGICAL MALDI-TOF/MS PROTEIN SPECTRA DATABASE FOR RELIABLE OENOLOGICAL YEAST AND BACTERIA IDENTIFICATION

The Matrix Assisted Laser Desorption/Ionization–Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) technology is commonly used in food and medical sector to identify yeast or bacteria species isolated from a nutritive culture media. Since a decade, brewery and oenology industries have been attracted to this method which combines fast analysis times, reliability and low cost of analysis. Briefly, this method is based on the comparison of the MALDI-TOF/MS protein spectra of an isolated colony of yeast or bacteria with those contain in a manufacturer’s reference protein spectra database. Initiated in 2015, the creation of the first oenological mass spectra database has proved to be essential for increase quality of species identification.

Read More