Identification of Key Parameters Inducing Microbial Modulation during Backslopped Kombucha Fermentation.

The aim of this study was to assess the impact of production parameters on the reproducibility of kombucha fermentation over several production cycles based on backslopping. Six conditions with varying oxygen accessibility (specific interface surface) and initial acidity (through the inoculation rate) of the cultures were carried out and compared to an original kombucha consortium and a synthetic consortium assembled from yeasts and bacteria isolated from the original culture. Output parameters monitored were microbial populations, biofilm weight, key physico-chemical parameters and metabolites.

Competition for Nitrogen Resources: An Explanation of the Effects of a Bioprotective Strain on the Growth of Genus in Oenology.

As a biological alternative to the antimicrobial action of SO, bioprotection has been proposed to winemakers as a means to limit or prevent grape musts microbial alteration. Competition for nitrogenous nutrients and for oxygen are often cited as potential explanations for the effectiveness of bioprotection. This study analyses the effect of a bioprotective strain on the growth of one strain and one strain.

Influence of pH on Oenococcus oeni metabolism: Can the slowdown of citrate consumption improve its acid tolerance?

Oenococcus oeni is the lactic acid bacteria most suited to carry out malolactic fermentation in wine, converting L-malic acid into L-lactic acid and carbon dioxide, thereby deacidifying wines. Indeed, wine is a harsh environment for microbial growth, partly because of its low pH. By metabolizing citrate, O.

Citrate metabolism in lactic acid bacteria: is there a beneficial effect for in wine?

Lactic acid bacteria (LAB) are Gram positive bacteria frequently used in the food industry for fermentation, mainly transformation of carbohydrates into lactic acid. In addition, these bacteria also have the capacity to metabolize citrate, an organic acid commonly found in food products. Its fermentation leads to the production of 4-carbon compounds such as diacetyl, resulting in a buttery flavor desired in dairy products.

Bioprotection Efficiency of Strains in Synthetic Must: Comparative Study and Metabolomic Investigation of the Mechanisms Involved.

Three strains marketed as bioprotection yeasts were studied to compare their antimicrobial effect on a mixture of two yeast strains in synthetic must at 12 °C, mimicking pre-fermentative maceration by combining different approaches. The growth of the different strains was monitored, their nitrogen and oxygen requirements were characterised, and their metabolomic footprint in single and co-cultures studied. Only the strain and one strains colonised the must and induced the rapid decline of .

Mixed biofilm formation by Oenococcus oeni and Saccharomyces cerevisiae: A new strategy for the wine fermentation process.

Bacterial biofilms have attracted much attention in the food industry since this phenotype increases microbial resistance to environmental stresses. In wine-making, the biofilm produced by Oenococcus oeni is able to persist in this harsh environment and perform malolactic fermentations. Certain viticultural practices are interested in the simultaneous triggering of alcoholic fermentation by yeasts of the species Saccharomyces cerevisiae and malolactic fermentation by lactic acid bacteria.

Must protection, sulfites versus bioprotection: A metabolomic study.

The reduction of chemical inputs in wine has become one of the main challenges of the wine industry. One of the alternatives to sulfites developed is bioprotection, which consists in using non-Saccharomyces strains to prevent microbial deviation. However, the impact of substituting sulfites by bioprotection on the final wine remains poorly studied.

Bio-protection in oenology by : from field results to scientific inquiry.

Finding alternatives to the use of chemical inputs to preserve the sanitary and organoleptic quality of food and beverages is essential to meet public health requirements and consumer preferences. In oenology, numerous manufacturers already offer a diverse range of bio-protection yeasts to protect must against microbiological alterations and therefore limit or eliminate sulphites during winemaking. Bio-protection involves selecting non- yeasts belonging to different genera and species to induce negative interactions with indigenous microorganisms, thereby limiting their development and their impact on the matrix.

To each their own: Delving into the vitaminic preferences of non-Saccharomyces wine yeasts.

Considering the growing interest in non-Saccharomyces wine yeasts, and notably in the context of mixed fermentations with S. cerevisiae, understanding their nutritional behaviors is essential to ensure better management of these fermentations. The vitaminic consumption of three non-Saccharomyces yeasts (Starmerella bacillaris, Metschnikowia pulcherrima and Torulaspora delbrueckii) was investigated during their growth in wine-like conditions, providing initial evidence that they consume different vitamers.

To be or not to be required: Yeast vitaminic requirements in winemaking.

Although vitamins are prime actors in yeast metabolism, the nature and the extent of their requirement in Saccharomyces cerevisiae in winemaking remains little understood. To fill this gap, the evolution of 8 water-soluble vitamins and their diverse vitamers during its alcoholic fermentation in a synthetic must medium was monitored, providing the first evidence of the consumption of vitamers by five commercial S. cerevisiae strains, and highlighting the existence of preferential vitameric sources for its nutrition.

Thiamine and Biotin: Relevance in the Production of Volatile and Non-Volatile Compounds during Alcoholic Fermentation in Synthetic Grape Must.

Vitamins are major cofactors to numerous key metabolic pathways in enological yeasts, and both thiamine and biotin, notably, are believed to be essential to yeast fermentation and growth, respectively. In order to further assess and clarify their role in winemaking, and in the resulting wine, alcoholic fermentations of a commercial active dried yeast were conducted in synthetic media containing various concentrations of both vitamins. Growth and fermentation kinetics were monitored and proved the essential character of biotin in yeast growth, and of thiamine in fermentation.

Experimental evolution forcing Oenococcus oeni acid tolerance highlights critical role of the citrate locus.

Oenococcus oeni is the main lactic acid bacterium associated with malolactic fermentation (MLF) of wines. MLF plays an important role in determining the final quality of wines. Nevertheless, due to the stressful conditions inherent to wine and especially acidity, MLF may be delayed.

Expanding the diversity of Chardonnay aroma through the metabolic interactions of cocultures.

Yeast co-inoculations in winemaking are often studied in the framework of modulating the aromatic profiles of wines. Our study aimed to investigate the impact of three cocultures and corresponding pure cultures of on the chemical composition and the sensory profile of Chardonnay wine. Coculture makes it possible to obtain completely new aromatic expressions that do not exist in the original pure cultures attributed to yeast interactions.

Use of Oenological Tannins to Protect the Colour of Rosé Wine in a Bioprotection Strategy with .

Although bioprotection is now recognised as an alternative to SO for limiting microbial spoilage, it does not guarantee protection against oxidation. This limits its application, more specifically for rosé winemaking. Oenological tannins present antioxidant properties, which could represent an interesting alternative to SO to protect must and wines against oxidation.

Exploring the unexplored: A characterization of vitamins and vitamers in white grape musts by high-performance liquid chromatography.

Although prime compounds in yeast metabolism, vitamins in oenology have remained mostly unexplored for decades. Here, a premier characterization of the vitamers in white grape musts has been drawn. A RP-HPLC method has therefore been developed for their direct analysis in musts, allowing for the determination of 19 different vitamers from 8 water-soluble vitaminic groups, including thiamine forms T, TMP and TPP, with LODs between 0.

Systematic and quantitative view of the antiviral arsenal of prokaryotes.

Bacteria and archaea have developed multiple antiviral mechanisms, and genomic evidence indicates that several of these antiviral systems co-occur in the same strain. Here, we introduce DefenseFinder, a tool that automatically detects known antiviral systems in prokaryotic genomes. We use DefenseFinder to analyse 21000 fully sequenced prokaryotic genomes, and find that antiviral strategies vary drastically between phyla, species and strains.

Oxygen management during kombucha production: Roles of the matrix, microbial activity, and process parameters.

Oxygen plays a key role in kombucha production, since the production of main organic acids, acetic and gluconic acids, is performed through acetic acid bacteria's oxidative metabolism. Oxygen consumption during traditional kombucha production was investigated by comparing kombucha to mono and cocultures in sugared tea of microorganisms isolated from kombucha. Two yeasts, Brettanomyces bruxellensis and Hanseniaspora valbyensis and one acetic acid bacterium Acetobacter indonesiensis were used.

Use of a Minimal Microbial Consortium to Determine the Origin of Kombucha Flavor.

Microbiological, chemical, and sensory analyses were coupled to understand the origins of kombucha organoleptic compounds and their implication in the flavor of the kombucha beverage. By isolating microorganisms from an original kombucha and comparing it to monocultures and cocultures of two yeasts ( and ) and an acetic acid bacterium (), interaction effects were investigated during the two phases of production. 32 volatile compounds identified and quantified by Headspace-Solid Phase-MicroExtraction-Gas Chromatography/Mass Spectrometry (HS-SPME-GC/MS) were classified according to their origin from tea or microorganisms.

Microbial Interactions in Kombucha through the Lens of Metabolomics.

Kombucha is a fermented beverage obtained through the activity of a complex microbial community of yeasts and bacteria. Exo-metabolomes of kombucha microorganisms were analyzed using FT-ICR-MS to investigate their interactions. A simplified set of microorganisms including two yeasts ( and ) and one acetic acid bacterium () was used to investigate yeast-yeast and yeast-acetic acid bacterium interactions.

Non-Targeted Metabolomic Analysis of the Kombucha Production Process.

Kombucha is a traditional fermented beverage obtained from the transformation of sugared black tea by a community of yeasts and bacteria. Kombucha production recently became industrialized, but its quality standards remain poorly defined. Metabolomic analyses were applied using FT-ICR-MS to characterize the impacts of production phases and the type of tea on the non-volatile chemical composition of kombucha.

Evolution in Composition of Kombucha Consortia over Three Consecutive Years in Production Context.

Kombucha is a traditional drink obtained from sugared tea that is transformed by a community of yeasts and bacteria. Its production has become industrialized, and the study of the microbial community's evolution is needed to improve control over the process. This study followed the microbial composition of black and green kombucha tea over three consecutive years in a production facility using a culture-dependent method.

Different Wines from Different Yeasts? " Intraspecies Differentiation by Metabolomic Signature and Sensory Patterns in Wine".

Alcoholic fermentation is known to be a key stage in the winemaking process that directly impacts the composition and quality of the final product. Twelve wines were obtained from fermentations of Chardonnay must made with twelve different commercial wine yeast strains of . In our study, FT-ICR-MS, GC-MS, and sensory analysis were combined with multivariate analysis.