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.Winemaking involves a mixed culture of numerous microorganisms including fungal, yeast, and bacteria species (6). The principal bacteria present in wine are members of the lactic acid bacteria (LAB), acetic acid bacteria (AAB), and to a lesser extent species of bacilli (13). LAB and AAB are often present on the surface of the grape and can represent significant populations in musts (17). LAB play dual roles in wine fermentations: as agents of wine spoilage and as the main effector of secondary, or malolactic, fermentation. Most LAB found in wine, including members of Oenococcus, Lactobacillus, Pediococcus, and Leuconostoc, are microaerophilic and able to grow in the anaerobic environment of fermenting wine (24). In contrast, wine-related AAB, such as members of Gluconobacter or Gluconacetobacter, are obligately aerobic and loosely categorized as vinegar bacteria (7,24). Both AAB and LAB can produce acetic acid, a potential inhibitor of growth and alcohol production by Saccharomyces cerevisiae (18).Most bacterial species present in wine fermentations have been identified by traditional microbiological techniques involving cultivation. However, as observed with microbial ecological studies of other environments, cultivation-dependent methods often exhibit biases resulting in an incomplete representation of the true bacterial diversity present (1, 16). Applications of culture-independent molecular techniques to monitor the microbial successions of various food and beverage fermentations have revealed microbial constituents and microbial interactions not witnessed by previous plating analyses (14). One example of this is the recent use of epifluorescence microscopy to identify populations of viable but not culturable bacteria (both LAB and AAB) in aging wine (20).Denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis ...

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 ‡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.

No abstract

No abstract

Lysozyme and the reduction of metabisulfite addition to red wine were evaluated during a winemaking process and after malolactic fermentation (MLF). Treatment, with lysozyme, of the must from Tempranillo grapes and at the end of alcoholic fermentation (AF) caused the 100% implantation of the inoculated bacterial strain and shortened the duration of MLF by 7 days. At the end of the MLF, wines treated with lysozyme showed lower volatile acidity, color intensity, and biogenic amine content. The differences in color intensity disappeared during wine stabilization. The lysozyme addition after MLF led to lower histamine concentrations in wines. These phenomena occurred irrespective of the lactic acid bacteria (LAB) proliferation control and of the Oenococcus oeni dominant strain identified at this period. The results of this study show the significance of preventive use of lysozyme in vinification of red wine to maintain low histamine levels and ensure a successful implantation of inoculated O. oeni starters.