Partial vinylphenol reductase purification and characterization from Brettanomyces bruxellensis
International audience; Brettanomyces is the major microbial cause for wine spoilage worldwide and causes significant economic losses. The reasons are the production of ethylphenols that lead to an unpleasant taint described as 'phenolic odour'. Despite its economic importance, Brettanomyces has remained poorly studied at the metabolic level. The origin of the ethylphenol results from the conversion of vinylphenols in ethylphenol by Brettanomyces hydroxycinnamate decarboxylase. However, no information is available on the vinylphenol reductase responsible for the conversion of vinylphenols in ethylphenols. In this study, a vinylphenol reductase was partially purified from Brettanomyces bruxe…
Advances in plant materials, food by-products, and algae conversion into biofuels: use of environmentally friendly technologies
Green technologies have emerged as useful tools for the generation of clean fuels with the potential to minimize the effect of human activity on the environment. Currently, these fuels are mainly composed of hydrocarbons obtained from crude oil. Over the past two decades, biomass has gained significant attention as a renewable feedstock for more sustainable biofuel production and has been a great candidate to replace fossil fuels. The principal components of most of the available biomass are cellulose, hemi-cellulose, and lignin. Although the available green technologies for biofuel production are progressing rapidly, productivity and chemical yield from these techniques are still below the…
Obtaining antioxidants and natural preservatives from food by-products through fermentation: A review
Industrial food waste has potential for generating income from high-added-value compounds through fermentation. Solid-state fermentation is promising to obtain a high yield of bioactive compounds while requiring less water for the microorganism’s growth. A number of scientific studies evinced an increase in flavonoids or phenolics from fruit or vegetable waste and bioactive peptides from cereal processing residues and whey, a major waste of the dairy industry. Livestock, fish, or shellfish processing by-products (skin, viscera, fish scales, seabass colon, shrimp waste) also has the possibility of generating antioxidant peptides, hydrolysates, or compounds through fermentation. These bioacti…
Modes d’invasion et d’expression de Botrytis cinerea, champignon pathogène de la Vigne
Introduction : Le champignon phytopathogene Botrytis cinerea est un polyphage qui cause d'enormes degâts en agriculture. La culture de la vigne represente en France des enjeux economiques importants. La vigne est touchee par la maladie de la pourriture grise due a B. cinerea, conduisant a des pertes de rendement importantes. L'objectif de cette etude est, compte tenu des effets sur le developpement fongique de facteurs environnementaux (Sautour et al., 2001a, b), la caracterisation du caractere pathogene et la comparaison des structures de populations de B. cinerea isolees de differentes regions de France : Bourgogne, Languedoc et Champagne. Materiel et methodes : Les suspensions de conidie…
Nutritional and microbiological quality of tiger nut tubers (Cyperus esculentus), derived plant-based and lactic fermented beverages
International audience; Tiger nut (Cyperus esculentus) is a tuber that can be consumed raw or processed into beverages. Its nutritional composition shows a high content of lipid and dietary fiber, close to those of nuts, and a high content of starch, like in other tubers. Tiger nuts also contain high levels of phosphorus, calcium, and phenolic compounds, which contribute to their antioxidant activity. From those characteristics, tiger nuts and derived beverages are particularly relevant to limit food insecurity in regions where the plant can grow. In Europe and United States, the tiger nut derived beverages are of high interest as alternatives to milk and for gluten-free diets. Fermentation…
A microbiological, physicochemical, and texture study during storage of yoghurt produced under isostatic pressure
Abstract This work aimed to study refrigeration storage (4 °C for 23 days) of yoghurt produced at 43 °C under sub-lethal high pressure, at 10, 20, 30 and 40 MPa, in comparison with the fermentation process at atmospheric pressure (0.1 MPa). Lactic acid bacteria (S. thermophilus and L. bulgaricus, LAB) and quality parameters like pH, titratable acidity, syneresis and colour were evaluated, along with textural analyses to infer how pressure would impact the obtained yoghurt along storage. Higher fermentation pressures resulted in slightly lower LAB loads (a maximum of 1.01 Log (CFU/mL)) and increased the fermentation time (a maximum of 3 h 25 min), syneresis (a maximum of 44%), all for 40 MPa…
Insights into genome plasticity of the wine-making bacterium Oenococcus oeni strain ATCC BAA-1163 by decryption of its whole genome.
International audience; Studying genomes of O. oeni strains having opposite oenological aptitudes is important for understanding why this lactic acid bacterium involved in malolactic fermentation is so well adapted to wine. Here, the genome of a strain ATCC BAA-1163, is described and compared with the recently reported genome of the better wine-adapted strain PSU-1. The BAA-1163 genome (8X) was obtained by shotgun sequencing and Phrap assembling. Compact and 62% AT-rich, it consists of a circular 1,792,103-bp chromosome and a 3,948-bp plasmid. It was analysed through a CAAT-Box annotation platform and manually inspected. A total of 51 RNA genes were detected, including two rRNA operons (the…
The impact of fermentation processes on the production, retention and bioavailability of carotenoids: An overview
Abstract Background Carotenoids are isoprenoids compounds widely distributed in foods. A difference of carotenoids relative to other food bioactives is that some can be converted into compounds exhibiting vitamin A activity, which is essential for humans. Besides, they are more versatile as they are also natural pigments, antioxidants and can be involved in health-promoting actions. Lately, they are also attracting interest in relation to skin beauty. Their importance for different industry sector (foods, feeds, pharmaceutical, cosmetics) is therefore indisputable. Carotenoids can be obtained by different approaches including extraction from appropriate sources or synthesis. Scope and appro…
Oligopeptide assimilation and transport by Oenococcus oeni
International audience; Aims: Oenococcus oeni is a slow-growing wine bacterium with a low growth yield. It thrives better on complex nitrogen sources than on free amino-acid medium. We aimed to characterize the oligopeptide use of this micro-organism. Methods and Results: Several peptides of two to eight amino-acid residues were able to provide essential amino acids. The disappearance of various peptides from extracellular medium was assessed with whole cells. Initial rates of utilization varied with the peptide, and free amino acids were released into the medium. Conclusions: Oenococcus oeni was able to transport the oligopeptides with two to five amino-acid residues tested and to hydrolys…
Characterization of EprA, a major extracellular protein of Oenococcus oeni with protease activity
International audience; Extracellular proteins from Oenococcus oeni. a wine-making bacterium, were isolated during growth on media differing by their nitrogen content. Analysis by two-dimensional electrophoresis revealed a low number of protein signals. Among the main spots, one signal corresponded to a single protein, which contained a lysine repeat domain characteristic of cell-wall hydrolases. We demonstrated that this major protein, named EprA, was able to hydrolyse several proteins. The heterologous production of this protein in Escherichia coli confirmed the protease activity of EprA. With a MW of 21.3 kDa and a pl of 5.3, EprA presents optimal activity at pH 7.0 and 45 degrees C. Thi…
Fermentation in fish and by-products processing: an overview of current research and future prospects
Fish industry has been growing continuously over the last decades and generates huge amounts of by-products. These by-products come from fish head, skin, bones, thorns, and viscera. Part of them are processed for feed, collagen and oil production, and to a lesser extent to produce biofuels and fertilizers, but many other high-value bioactive compounds can be recovered. Fish fermentation, which is traditionally used to increase fish shelf-life, results into the formation of bacteria metabolites of interest. Applied to by-products, fermentation increases the quality of protein hydrolysates, oil and produces antioxidant compounds. This technology, which is safe, environmental-friendly and poor…
Nutritional, chemical, syneresis, sensory properties, and shelf life of Iranian traditional yoghurts during storage
Tuluq and Torba yoghurts are traditional concentrates from Iran. Physicochemical, nutritional, and sensory properties of these yoghurts were studied along 60 days of storage. Results showed that, both pH and percentage of free whey decreased significantly (P < 0.05), while titratable acidity, total solid, salt, protein and fat content increased (P < 0.05) during storage. The yoghurt lipolysis decreased during the first 30 days and then increased during the storage. The indexes pH 4.6-soluble nitrogen/total nitrogen and non-protein nitrogen/total nitrogen in yoghurt samples decreased during first 30 days, possibly due to removing of low molecular weight nitrogenous compounds of Tuluq and Tor…
Application of Fermentation to Recover High‐Added Value Compounds from Food By‐Products
Effect of nitrogen limitation and nature of the feed upon Oenococcus oeni metabolism and extracellular protein production
Aims: The aim of the study was to characterize the effect of various nitrogen sources on Oenococcus oeni growth, carbon source utilization, extracellular protease activity and extracellular proteins. More generally, the goal is to understand how nitrogen-based additives might act to enhance malolactic fermentation in wine. Methods and Results: Five yeast extracts were used. As the amino acid and nitrogen analyses revealed, they were similar in global amino acid composition, except for arginine level. Nevertheless the ratio of amino acids between free/bound, and low/high molecular weight fractions were highly different. One of the yeast extracts led to a significant protease activity in th…
Characterization of the "viable but nonculturable" (VBNC) state in the wine spoilage yeast Brettanomyces.
Although the viable but not culturable (VBNC) state has been studied in detail in bacteria, it has been suggested that maintenance of viability with loss of culturability also exists in eukaryotic cells, such as in the wine spoilage yeast Brettanomyces. To provide conclusive evidence for the existence of a VBNC state in this yeast, we investigated its capacity to become viable and nonculturable after sulfite stress, and its ability to recover culturability after stressor removal. Sulfite addition induced loss of culturability but maintenance of viability. Increasing the medium pH to decrease the concentration of toxic SO(2) allowed yeast cells to become culturable again, thus demonstrating …
Design and performance testing of a real-time PCR assay for sensitive and reliable direct quantification of Brettanomyces in wine
International audience; Because the yeast Brettanomyces produces volatile phenols and acetic acid, it is responsible for wine spoilage. The uncontrolled accumulation of these molecules in wine leads to sensorial defects that compromise wine quality, The need for a rapid, specific, sensitive and reliable method to detect this spoilage yeast has increased over the last decade. All these requirements are met by real-time PCR. We here propose improvements of existing methods to enhance the robustness of the assay. Six different protocols to isolate DNA from a wine and three PCR mix compositions were tested, and the best method was selected. Insoluble PVPP addition during DNA extraction by a cla…
When yeast-bacterial interactions depend on the quality of wines
International audience; no abstract
Influence of different sources of vegetable, whey and microalgae proteins on the physicochemical properties and amino acid profile of fresh pork sausages
Abstract The purpose of this study was to evaluate changes in the physicochemical properties and amino acid profiles of pork sausages prepared by including vegetable protein sources (beans, peas, and lentils), microalgae (Chlorella and Spirulina) or whey, as compared with a control (soy protein). Significant differences were found for all the studied parameters. The protein content was significantly lower in sausages made with pea protein compared with the control. Colour parameters changed significantly after the incorporation of microalgae proteins. Moreover, significant differences among treatments were observed in the amino acid profile. The inclusion of Spirulina proteins resulted in a…
Peptidases specific for proline-containing peptides and their unusual peptide-dependent regulation in Oenococcus oeni
International audience; Growth of the lactic acid bacterium (LAB) Oenococcus oeni, which is involved in malolactic fermentation during the winemaking process, is stimulated by peptides originating from yeast. In this study, we investigated the impact of peptides on O. oeni growth, peptidase activity and the expression of genes encoding the studied peptidases. Low levels of PepN activity and very high levels of PepI activity were observed in O. oeni, whereas levels of PepX activity were intermediate. The level of biosynthesis of these O. oeni peptidases was shown to depend on peptides present in the culture medium. These results were confirmed by transcriptional analyses of putative pep gene…
Influence of Temperature, Solvent and pH on the Selective Extraction of Phenolic Compounds from Tiger Nuts by-Products: Triple-TOF-LC-MS-MS Characterization
The aim of this study was to assess the effect of temperature, solvent (hydroethanolic mixtures) and pH on the recovery of individual phenolic compounds from &ldquo
Role of biological control agents and physical treatments in maintaining the quality of fresh and minimally-processed fruit and vegetables
International audience; Fruit and vegetables are an important part of human diets and provide multiple health benefits. However, due to the short shelf-life of fresh and minimally-processed fruit and vegetables, significant losses occur throughout the food distribution chain. Shelf-life extension requires preserving both the quality and safety of food products. The quality of fruit and vegetables, either fresh or fresh-cut, depends on many factors and can be determined by analytical or sensory evaluation methods. Among the various technologies used to maintain the quality and increase shelf-life of fresh and minimally-processed fruit and vegetables, biological control is a promising approac…
Effects of yeast proteolytic activity on Oenococcus oeni and malolactic fermentation
International audience; Alcoholic fermentation of synthetic must was performed using either Saccharomyces cerevisiae or a mutant Delta pep4, which is deleted for the proteinase A gene. Fermentation with the mutant Delta pep4 resulted in 61% lower levels of free amino acids, and in 62% lower peptide concentrations at the end of alcoholic fermentation than in the control. Qualitative differences in amino acid composition were observed. Changes observed in amino acids in peptides were mainly quantitative. After alcoholic fermentation each medium was inoculated with Oenococcus oeni. Malolactic fermentation in the medium with the Delta pep4 strain took 10 days longer than the control. This diffe…
Opuntia Ficus Indica Edible Parts: A Food and Nutritional Security Perspective
Cactus Opuntia ficus indica is widely distributed in (semi-) arid regions. Fruit and cladodes are processed into many food products. Cladodes are used as vegetables, but their main use is flour, wh...
Specific Identification and Quantification of the Spoilage Microorganism Brettanomyces in Wine by Flow Cytometry: A Useful Tool for Winemakers
International audience; no abstract
Saccharomyces cerevisiae-Oenococcus oeni interactions in wine: current knowledge and perspectives.
Winemaking can be summarized as the biotransformation of must into wine, which is performed principally by Saccharomyces cerevisiae strains during the primary or alcoholic fermentation. A secondary fermentation, the so-called malolactic fermentation (MLF) is a biodeacidification that is often encouraged, since it improves wine stability and quality. Malolactic fermentation usually occurs either spontaneously or after inoculation with selected bacteria after alcoholic fermentation. The main organism responsible for MLF, the lactic acid bacterium Oenococcus oeni, develops in physicochemically harsh conditions, which may lead to MLF failure. Furthermore, yeast that ferment must before or toget…