A total of 76 Lactobacillus plantarum and Oenococcus oeni wild strains were recovered from traditionally elaborated Spanish red wines and were investigated with respect to their response to acid pH, lyophilisation, temperature and ethanol concentrations which are normally lethal to lactic acid bacteria. Both L. plantarum and O. oeni strains were able to grow at pH 3.2, were highly resistant to lyophilisation treatment and proliferated in the presence of up to 13% ethanol at 18 degrees C. Therefore, it is shown that both species are highly tolerant to stress conditions and that similarly to O. oeni strains, L. plantarum strains are of interest in beverage biotechnology.

Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified ribosomal DNA (rDNA) is routinely used to compare levels of diversity of microbial communities and to monitor population dynamics. While using PCR-DGGE to examine the bacteria in wine fermentations, we noted that several commonly used PCR primers for amplifying bacterial 16S rDNA also coamplified yeast, fungal, or plant DNA present in samples. Unfortunately, amplification of nonbacterial DNA can result in a masking of bacterial populations in DGGE profiles. To surmount this problem, we developed two new primer sets for specific amplification of bacterial 16S rDNA in wine fermentation samples without amplification of eukaryotic DNA. One primer set, termed WLAB1 and WLAB2, amplified lactic acid bacteria, while another, termed WBAC1 and WBAC2, amplified both lactic acid bacterial and acetic acid bacterial populations found in wine. Primer specificity and efficacy were examined with DNA isolated from numerous bacterial, yeast, and fungal species commonly found in wine and must samples. Importantly, both primer sets effectively distinguished bacterial species in wine containing mixtures of yeast and bacteria.

© 2014 Elsevier Ltd. In this work the influence of the foliar application of proline, phenylalanine, urea and two commercial nitrogen fertilizers, with and without amino acids, on grape aroma composition was studied. The treatments were applied in a Tempranillo vineyard, at a dose of total N of 900g/ha, at veraison and a week later. Enological parameters and volatile compound content were determined in grapes. The results showed that terpenoids synthesis decreased with all treatments carried out in the vineyard, and there were not significant differences either in the amount of C13 norisoprenoids or in esters between treated and control samples. The treatment with phenylalanine increased the presence of benzenoid compounds and decreased C6 compounds. Therefore, this treatment could be considered the best from the point of view of grape aroma composition. The treatments with the commercial nitrogen fertilizers did not affect the total compound content present in the samples.Many thanks for the financial support given by the Gobierno de La Rioja to project R-11-12. T. G.-C., L. G.-A., and I. L.-A. also wish to thank the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)-Gobierno de La Rioja and FEDER of the European Community for the doctoral and predoctoral contracts.Peer Reviewe