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Brettanomyces bruxellensis is an important wine spoilage agent. In this study a population of Brettanomyces strains isolated from Italian wines was thoroughly investigated to evaluate adaptability to wine conditions and spoilage potential. The presumptive isolates of Brettanomyces were identified at species level with 26S rRNA gene sequencing and species-specific PCR, and subsequently subjected to analysis of intra-species variability through the study of intron splice sites (ISS-PCR). Although, some strains were tracked in wines from different regions, extensive genetic biodiversity was observed within the B . bruxellensis population investigated. All strains were evaluated for their growth ability in the presence of ethanol, high sugar content, low pH, different temperatures and sulphur dioxide, using optical density and flow cytometry measurement. The ability of yeasts to produce ethyl phenols in red wines with different chemical compositions was evaluated by means of high performance liquid chromatography with electrochemical detection (HPLC-ECD). The results highlighted wide variability in B . bruxellensis in response to wine limiting factors and in terms of the accumulation of ethyl phenols. As regards this last aspect, the differences found among strains were closely related to chemical composition of wine and strain resistance to environmental stress factors, making a priori evaluation of risk of wine alteration quite difficult. These results suggest that strategies for the control of Brettanomyces should be tailored on the basis of strain distribution and wine characteristics. [ABSTRACT FROM AUTHOR]

Abstract: Several lactic acid bacteria (LAB) were evaluated in situ for their potential in sourdough fermentation. The strains belonged to Lactobacillus plantarum, Lactobacillus sakei, Lactobacillus sanfranciscensis, Leuconostoc citreum, Leuconostoc mesenteroides, Leuconostoc pseudomesenteroides and Weissella cibaria. LAB were used, in individual inocula, to carry out the fermentation of γ-ray treated (sterile) flour and untreated commercial flour, in order to evaluate their performances both in the absence and presence of the native microbiota of flour. The pH and total titratable acidity (TTA) showed a strong and fast acidification of the experimental sourdough determined by W. cibaria and Ln. citreum strains. All strains were followed during fermentation by plate count. Randomly amplified polymorphic DNA (RAPD)-PCR analysis applied on the colonies isolated from the highest dilution of samples confirmed the dominance of the added strains in all sourdoughs prepared with sterile and non-sterile flour. The analysis of organic acids, performed by high-performance liquid chromatography (HPLC), confirmed that some W. cibaria and Ln. citreum strains showed an optimal fermentation quotient. The volatile organic compound (VOC) composition resulting from the gas chromatography coupled with mass spectrometry (GC/MS) analysis of sourdough headspace recognised 51 chemical compounds including acids, alcohols, aldehydes, esters, ketones, lactones, acetate, alkane, and phenol, most of which are of LAB origin and are relevant for the final bread. After baking, the breads were evaluated for the height of the central slices, colour of crust and crumb, hardness and number and distribution of alveolus. The combination of these results indicated that strains Ln. citreum PON10079 and PON10080 and W. cibaria PON10030 and PON10032 are suitable cultures to use in industrial production. [Copyright &y& Elsevier]