Project description:The correct development of malolactic fermentation depends on the capacity of Oenococcus oeni to survive under harsh wine conditions. In this study it was characterized the transcriptomic response of O. oeni PSU-1 during the adaptation to wine-like medium (WLM). The period evaluated was from the inoculation into WLM (12% v/v pH 3.4) until the beginning of malolactic fermentation (8h after inoculation).
Project description:Malolactic fermentation (MLF) positively influences the quality of the wine, and it occurs as a result of a lactic acid bacteria’s metabolism, mainly of the Oenococcus oeni species. However, delays and halting of MLF are frequent problems in the wine industry. This is mainly because O. oeni’s development is inhibited by different kinds of stress. Even though the sequencing of the genome of the PSU-1 strain of O. oeni, as well as other strains, has made it possible to identify genes involved in the resistance to some types of stress, all of the factors that could be involved are still unknown. With the aim of contributing to this knowledge, the random mutagenesis technique was used in this study as a strategy for genetic improvement of strains of the O. oeni species. The technique proved to be capable of generating a different and improved strain when compared to the PSU1 strain (the parent from which it descends). Then, we evaluated the metabolic behavior of both strains in three different wines. We used synthetic MaxOeno wine (pH 3.5; 15% v/v ethanol), red wine (Cabernet Sauvignon) and white wine (Chardonnay). Furthermore, we compared the transcriptome of both strains, grown in MaxOeno synthetic wine. The specific growth rate of the E1 strain was on average 39% higher in comparison to the PSU1 strain. Interestingly, E1 strain showed an overexpression of the OEOE_1794 gene, which encodes a UspA-like protein, which has been described as promoting growth. We observed that the E1 strain was able to convert, on average, 34% more malic acid into lactate than the PSU1 strain, regardless of the wine being used. On the other hand, the E1 strain showed a flux rate of fructose-6-phosphate production that was 86% higher than the mannitol production rate, and the internal flux rates increase in the direction of pyruvate production. This coincides with the higher number of OEOE_1708 gene transcripts observed in the E1 strain grown in MaxOeno. This gene encodes for an enzyme fructokinase (EC 2.7.1.4) involved in the transformation of fructose to fructose-6-phosphate. It is necessary to continue studying these genes in order to verify their biological function in O. oeni and their impact on MLF.
Project description:The yeast Saccharomyces cerevisiae is an important component of the wine fermentation process and determines various attributes of the final product. However, lactic acid bacteria (LAB) are also an integral part of the microflora of any fermenting must. Various wine microorganism engineering projects have been endeavoured in the past in order to change certain wine characteristics, namely aroma compound composition, ethanol concentration, levels of toxic/ allergenic compounds etc. Most of these projects focus on a specific gene or pathway, whereas our approach aims to understand the genetically complex traits responsible for these phenotypes in a systematic manner by implementing a transcriptomic analysis of yeast in mixed fermentations with the LAB O. oeni. Our aim is to investigate interactions between yeast and LAB on a gene expression level to identify targets for modification of yeast and O. oeni in a directed manner. Our goal was to identify the impact that the common wine microorganism O. oeni (malolactic bacteria) has on fermenting yeast cells on a gene expression level. To this end we co-inoculated the yeast and bacteria at the start of fermentation in a synthetic wine must, using yeast-only fermentations witout O. oeni as a control. Fermentations were carried out in synthetic wine must in triplicate for both the control S. cerevisiae VIN13 strain and the mixed fermentation of VIN13 and O. oeni (strain S5). Sampling of yeast for RNA extractions were performed at day 3 of fermentation, during the exponential growth phase of the yeast cells, and again at day 7 of fermentation, during the early stationary growth phase.
Project description:The yeast Saccharomyces cerevisiae is an important component of the wine fermentation process and determines various attributes of the final product. However, lactic acid bacteria (LAB) are also an integral part of the microflora of any fermenting must. Various wine microorganism engineering projects have been endeavoured in the past in order to change certain wine characteristics, namely aroma compound composition, ethanol concentration, levels of toxic/ allergenic compounds etc. Most of these projects focus on a specific gene or pathway, whereas our approach aims to understand the genetically complex traits responsible for these phenotypes in a systematic manner by implementing a transcriptomic analysis of yeast in mixed fermentations with the LAB O. oeni. Our aim is to investigate interactions between yeast and LAB on a gene expression level to identify targets for modification of yeast and O. oeni in a directed manner. Our goal was to identify the impact that the common wine microorganism O. oeni (malolactic bacteria) has on fermenting yeast cells on a gene expression level. To this end we co-inoculated the yeast and bacteria at the start of fermentation in a synthetic wine must, using yeast-only fermentations witout O. oeni as a control.
Project description:Oenococcus oeni is the main lactic acid bacterium that carries out the malolactic fermentation in virtually all red wines and in some white and sparkling wines. O. oeni possesses an array of metabolic activities which can modify the taste and aromatic properties of wine. There is therefore industrial interest in the proteins involved in these metabolic pathways and related transport systems of this bacterium. In this work, we report the characterization of the O. oeni ATCC BAA-1163 proteome. Total and membrane protein preparations from O. oeni were standardized and analyzed by two-dimensional gel electrophoresis. Using tandem mass spectrometry we identified 226 different polypeptides corresponding to 155 unique proteins, which have been classified by their putative function and subjected to bioinformatics analysis.
Project description:In this work, three O.oeni strians were inoculated, two of them were of our own collection (3P2 and 2T2) and the other one is the type strain 217T (=ATCC 23279) in WLM-12 to develop MLF in these conditions (Bordas et al, 2015). Basic fermentation characteristics were monitored, such as growth rate and biomass yield, as well as the respective transcriptome. This approach allowed a better understanding of metabolic adaptation and its association with specific genes expression profiles, likewise we were able to identify some biological process directly involved in the fermentation conditions such as pH or ethanol content.