J. Basic Microbiol. 44 (2004) 1, 10 – 16 DOI: 10.1002/jobm.200310281 © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 0233-111X/04/0102-0010 (Department of Food Science, University of Foggia, via Napoli, 25, 71100 Foggia, Italy Molecular characterization of lactic acid populations associated with wine spoilage L. BENEDUCE, G. SPANO*, A. VERNILE, D. TARANTINO and S. MASSA (Received 04 April 2003/Accepted 01 July 2003) We have investigated the prevalence of spoilage lactic acid bacteria (LAB) in table wines produced in the Apulia region. The occurrence of LAB was evaluated in wines produced with low sulphur dioxide doses and not supplemented with selected malolactic starters such as Oenococcus oeni. About 150 strains were isolated from wine must and a molecular characterization was performed using PCR- based techniques. Most of the strains analysed belonged to Lactobacillus plantarum species. However, some of the strains were identified as Pediococcus damnosus and Leuconostoc sp. The amplified fragments of Pediococcus damnosus were cloned and sequenced. The coding sequence was highly homologous to that of the ropy plasmid confirming that the isolated strain was a ropy + Pediococcus damnosus. In all the samples analysed, the final must pH value reached was relatively high (from 3.78 to 3.90). The high pH values had probably negatively influenced (counteracted) the activity of sulphur dioxide added, allowing proliferation of spoilage wine microorganisms. During malolactic fermentation (MLF), lactic acid bacteria (LAB) lead to a biological deacidification of wine, due to the conversion of bicarboxylic malic acid into monocarb- oxylic lactic acid and a broad range of secondary compositional modifications of great im- portance for taste and flavour improvement of wine (LIU 2002). When all the malic acid is degraded, wines are usually stabilized by sulfiting. Sulphur dioxide is at this stage of wine- making the only authorized and efficient agent for the stabilization of wine (LONVAUD- FUNEL 1999). Most of the bacteria and possibly the remaining yeasts are sensitive to sulfur dioxide. However, for health reasons, high doses of sulphur dioxide are not recommended (DELFINI et al. 1992). Furthermore, the activity of sulphur dioxide is related to pH. In wines with high pH, the ineffectiveness of sulphur dioxide may enhance survival of spoilage bac- teria. In these conditions, Lactobacillus and Pediococcus are frequently predominant and can induce spoilage. Only physical treatments such as heat treatment or filtration can even- tually eliminate all the viable bacteria (LONVAUD-FUNEL 1999). In some areas, especially in south of Italy, although the majority of wine makers still prefer to produce homemade wines, some of them has begun to build up small commercial wineries. In either case, however, no selected malolactic starters are used and the table wines produced sometimes have, a low quality and bitter taste. Furthermore, low doses of sulphur dioxide are usually added during or at the end of MLF. Understanding the importance of using selected starters during MLF and identifying the predominant LAB population during MLF should be of great value in order to predict either the frequency of spoilage microorganisms or to improve wine quality produced by small wineries. The improvement of molecular tools, usually based on PCR techniques, has al- lowed a fast and sensitive characterization of the majority of wine LAB. However, the same tools should be available and easily understandable even for small winery that might use them to improve their wine quality. * Corresponding author: Dr. G. SPANO; e-mail: g.spano@unifg.it