Biodiversity of Dekkera/Brettanomyces in Apulian wines: isolation, characterization of representative biotypes and assessment of control strategies based on biotechnological resources management

ABSTRACT BACKGROUND Among all the possible microbial contaminations of wine, development of Brettanomyces bruxellensis yeast is the most dreaded by winemakers. Indeed, growth of yeasts belonging to Dekkera/Brettanomyces during wine manufacturing, can seriously affect the quality of the final product, especially during aging. Spoilage yeasts of the genus Brettanomyces or its teleomorph Dekkera are well adapted to survive during the winemaking process, due to their ethanol tolerance and relative resistance to the normal concentrations of sulphur dioxide found in wine. To prevent the development of this yeast in wine, it is important to know the biodiversity of Brettanomyces bruxellensis. A more detailed study of these aspects could help winemakers to learn more about this yeast and to implement preventive and fighting measures to try to reduce the economic losses caused by B. bruxellensis. AIM OF THE STUDY The specific objectives of this work were to isolate Brettanomyces strains from several wineries located in Puglia and to characterize representative biotypes, in order to evaluate control strategies based on biotechnological resources management. MATERIAL and METHODS Yeasts of the genus Brettanomyces were selected in tank, barrel and fermenting must of several Apulian wines. The yeast strains were identified and genetically characterized using restriction pattern analysis of the internal transcribed spacer region (5.8S-ITS), species-specific primers and restriction analysis. Biodiversity of selected B. bruxellensis strains was studied with Sau-PCR. Potential spoilage and VBNC behavior of different biotype were studied with gas chromatograph and flow cytometry. The cells of Brettanomyces were quantified in wine with Real Time PCR. To reduce the volatile phenols in wine and the growth of Brettanomyces bruxellensis different preparations of yeast cell wall and chitosan, respectively, were used.