Exopolysaccharides producing lactic acid bacteria in wine and other fermented beverages: For better or for worse?

Lactic acid bacteria (LAB) from fermented beverages such as wine, cider and beer produce a wide range of exopolysaccharides (EPS) through multiple biosynthetic pathways. These extracellular polysaccharides constitute key elements for bacterial species adaptation to such anthropic processes. In the food industry, LAB polysaccharides have been widely studied for their rheological, functional and nutritional properties; however, these have been poorly studied in wine, beer and cider until recently. In this review, we have gathered the information available on these specific polysaccharide structure and, biosynthetic pathways, as well as the physiology of their production. The genes associated with EPS synthesis are also presented and compared. Finally, the possible role of EPS for bacterial survival and spread, as well as the risks or possible benefits for the winemaker and the wine lover, are discussed

Studies on <i>gtf</i>, a glucosyltransferase gene in the genome of <i>Pediococcus parvulus</i> and <i>Oenococcus oeni</i>, two bacterial species commonly found in wine

International audienc

Evidence for exopolysaccharide production by <i>Oenococcus oeni</i> strains isolated from non-ropy wines

International audienc

Changes in red wine soluble polysaccharide composition induced by malolactic fermentation

International audienc

Mol Biotechnol

Oenococcus oeni is the main bacterial species that drives malolactic fermentation in wine. Most O. oeni strains produce capsular exopolysaccharides (EPS) that may contribute to protect them in the wine hostile environment. In O. oeni genome sequences, several genes are predicted to encode priming glycosyltransferases (pGTs). These enzymes are essential for EPS formation as they catalyze the first biosynthetic step through the formation of a phosphoanhydride bond between a hexose-1-phosphate and a lipid carrier undecaprenyl phosphate. In many microorganisms, mutations abolishing the pGT activity also abolish the EPS formation. We first made an in silico analysis of all the genes encoding putative pGT over 50 distinct O. oeni genome sequences. Two polyisoprenyl-phosphate-hexose-1-phosphate transferases, WoaA and WobA, and a glycosyltransferase (It3) were particularly examined for their topology and amino acid sequence. Several isoforms of these enzymes were then expressed in E. coli, and their substrate specificity was examined in vitro. The substrate specificity varied depending on the protein isoform examined, and several mutations were shown to abolish WobA activity but not EPS synthesis. Further analysis of woaA and wobA gene expression levels suggests that WoaA could replace the deficient WobA and maintain EPS formation

Phylogenomic Analysis of Oenococcus oeni Reveals Specific Domestication of Strains to Cider and Wines.

International audienceOenococcus oeni is a lactic acid bacteria species encountered particularly in wine, where it achieves the malolactic fermentation. Molecular typing methods have previously revealed that the species is made of several genetic groups of strains, some being specific to certain types of wines, ciders or regions. Here, we describe 36 recently released O. oeni genomes and the phylogenomic analysis of these 36 plus 14 previously reported genomes. We also report three genome sequences of the sister species Oenococcus kitaharae that were used for phylogenomic reconstructions. Phylogenomic and population structure analyses performed revealed that the 50 O. oeni genomes delineate two major groups of 12 and 37 strains, respectively, named A and B, plus a putative group C, consisting of a single strain. A study on the orthologs and single nucleotide polymorphism contents of the genetic groups revealed that the domestication of some strains to products such as cider, wine, or champagne, is reflected at the genetic level. While group A strains proved to be predominant in wine and to form subgroups adapted to specific types of wine such as champagne, group B strains were found in wine and cider. The strain from putative group C was isolated from cider and genetically closer to group B strains. The results suggest that ancestral O. oeni strains were adapted to low-ethanol containing environments such as overripe fruits, and that they were domesticated to cider and wine, with group A strains being naturally selected in a process of further domestication to specific wines such as champagne

Researh on the origin and the side effects of chitosan stabilizing properties in wine

International audienc

Carbohydrate metabolism in Oenococcus oeni: a genomic insight

Abstract Background Oenococcus oeni is the bacterial species that drives malolactic fermentation in most wines. Several studies have described a high intraspecific diversity regarding carbohydrate degradation abilities but the link between the phenotypes and the genes and metabolic pathways has been poorly described. Results A collection of 41 strains whose genomic sequences were available and representative of the species genomic diversity was analyzed for growth on 18 carbohydrates relevant in wine. The most frequently used substrates (more than 75% of the strains) were glucose, trehalose, ribose, cellobiose, mannose and melibiose. Fructose and L-arabinose were used by about half the strains studied, sucrose, maltose, xylose, galactose and raffinose were used by less than 25% of the strains and lactose, L-sorbose, L-rhamnose, sorbitol and mannitol were not used by any of the studied strains. To identify genes and pathways associated with carbohydrate catabolic abilities, gene-trait matching and a careful analysis of gene mutations and putative complementation phenomena were performed. Conclusions For most consumed sugars, we were able to propose putatively associated metabolic pathways. Most associated genes belong to the core genome. O. oeni appears as a highly specialized species, ideally suited to fermented fruit juice and more specifically to wine for a subgroup of strains