A partial proteome reference map of the wine lactic acid bacterium Oenococcus oeni ATCC BAA-1163

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. Oenococcus oeni possesses an array of metabolic activities that 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 analysed by two-dimensional gel electrophoresis. Using tandem mass spectrometry, we identified 224 different spots corresponding to 152 unique proteins, which have been classified by their putative function and subjected to bioinformatics analysis

Enhancement of 2-methylbutanal formation in cheese by using a fluorescently tagged Lacticin 3147 producing Lactococcus lactis strain

30 p.-6 fig.The amino acid conversion to volatile compounds by lactic acid bacteria is important for aroma formation in cheese. In this work, we analyzed the effect of the lytic bacteriocin Lacticin 3147 on transamination of isoleucine and further formation of the volatile compound 2-methylbutanal in cheese. The Lacticin 3147 producing strain Lactococcus lactis IFPL3593 was fluorescently tagged (IFPL3593-GFP) by conjugative transfer of the plasmid pMV158GFP from Streptococcus pneumoniae, and used as starter in cheese manufacture. Starter adjuncts were the bacteriocin-sensitive strains L. lactis T1 and L. lactis IFPL730, showing branched chain amino acid aminotransferase and α-keto acid decarboxylase activity, respectively. Adjunct strains were selected to complete the isoleucine conversion pathway and, hence, increase formation of 2-methylbutanal conferring aroma to the cheese. The non-bacteriocin-producing strain L. lactis IFPL359-GFP was included as starter in the control batch. Fluorescent tagging of the starter strains allowed their tracing in cheese during ripening by fluorescence microscopy and confocal scanning laser microscopy. The bacteriocin produced by L. lactis IFPL3593-GFP enhanced lysis of the adjuncts with a concomitant increase in isoleucine transamination and about a two-fold increase of the derived volatile compound 2-methylbutanal. This led to an enhancement of the cheese aroma detected by a sensory panel. The improvement of cheese flavour and aroma may be of significant importance for the dairy industry. © 2003 Elsevier B.V. All rights reserved.The research was supported by the NRI Competitive Grants Program of the United States Department of Agriculture (Grant no. 2002-35204-11662) and Schering-Plough Animal Health CorpPeer Reviewe

Comparative Proteomic Analysis of <em>Lactobacillus</em> <em>plantarum</em> WCFS1 and Δ<em>ctsR</em> Mutant Strains Under Physiological and Heat Stress Conditions

Among Gram-positive bacteria, CtsR (Class Three Stress gene Repressor) mainly regulates the expression of genes encoding the Clp ATPases and the ClpP protease. To gain a better understanding of the biological significance of the CtsR regulon in response to heat-shock conditions, we performed a global proteomic analysis of <em>Lactobacillus</em> <em>plantarum</em> WCFS1 and ∆<em>ctsR</em> mutant strains under optimal or heat stress temperatures. Total protein extracts from bacterial cells were analyzed by two-dimensional gel fractionation. By comparing maps from different culture conditions and different <em>L.</em> <em>plantarum</em> strains, image analysis revealed 23 spots with altered levels of expression. The proteomic analysis of <em>L.</em> <em>plantarum</em> WCFS1 and <em>ctsR</em> mutant strains confirms at the translational level the CtsR-mediated regulation of some members of the Clp family, as well as the heat induction of typical stress response genes. Heat activation of the putative CtsR regulon genes at transcriptional and translational levels, in the <em>∆ctsR</em> mutant, suggests additional regulative mechanisms, as is the case of <em>hsp1</em>. Furthermore, isoforms of ClpE with different molecular mass were found, which might contribute to CtsR quality control. Our results could add new outlooks in order to determine the complex biological role of CtsR-mediated stress response in lactic acid bacteria