Novel insights into microbial community dynamics during the fermentation of Central European ice wine

Culture-dependent and culture-independent strategies were applied to investigate the microbiota of autumn undamaged and damaged berries, winter berries and ice wine must samples of Gruner Veltliner (Veltlinske zelene) from Small Carpathian wine-producing region. One hundred twenty-six yeasts and 242 bacterial strains isolated from several microbiological media (YPD, PDA, R2A, GYC, MRS and MRS-T) were clustered by ITS-PCR and subsequent Qiaxcel electrophoresis. Representatives of each cluster were identified by sequencing. The extracellular hydrolytic properties and intracellular activities of esterase and beta-glucosidase of isolates were assayed. The culture-independent approach permitted the analysis of extracted DNA and RNA coupling DGGE fingerprinting with construction of clone libraries (bacterial and fungal; DGGE-cloning). The combination of the two approaches provided comprehensive data that evidenced the presence of a complex microbiota in each analyzed sample. RNA and DNA analyses facilitated differentiation of living microorganisms from the entire microbiota. Diverse microbial communities colonized the autumn and winter berries. Generally, the combination of results obtained by the methods suggested that the must samples contained mainly Saccharomyces cerevisiae, Metschnikowia spp., Hanseniaspora uvarum, Lactococcus lactis and Leuconostoc spp. The strains exhibited interesting esterase and beta-glucosidase properties, which are important for aroma formation in wine. Fermentation strategies utilising these microorganisms, could be attempted in the future in order to modulate the ice wine characteristics.