Identification of AAB based only on morphological, biochemical, and physiological characteristics is not reliable and, therefore, is insufficient because of the poor reproducibility and discriminatory power of these phenotypic tests . For this reason, nucleic acid-based molecular methods are now used to characterize and identify isolates of AAB from wine and vinegar ecosystems .These have included Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR), Repetitive Extragenic Palindromic-PCR (REP-PCR) (González et al.,, (GTG) 5 -rep-PCR fingerprinting and RAPD-PCR A reliable taxonomic identification is obtained when these techniques are combined with the sequencing of 16S rDNA genes and internal transcribed spacer sequences(ITS) of the 16S–23S rDNA genes. Restriction fragment length polymorphism (RFLP) analysis of the ribosomal genes or their spacer regions has also been used for the identification of AAB present in food-related ecosystems
The combination of culture-independent methods with culture-dependent methods in a polyphasic system is recommended as an effective approach to overcome the difficulties regarding the isolation and cultivation of AAB strains . In the last decade, several studies using the culture-independent DGGE and Temporal Tempera-ture Gradient Gel Electrophoresis (TTGE) techniques were reported for the characterization of the microbial community in vinegar and the determination of population dynamics of AAB during fermentation In addition, the real-time PCR technique has also been proposed for culture-independent detection of different genera, or species, of AAB. Recently,the intercalating dye-based real-time PCR analysis involved in specific melting temperature (Tm) and high-resolution melting analysis were applied as a highly promising new approach for confirming the identification and grouping of the culturable strains belonging to different bacterial species,but not yet to AAB. These new approaches provide a rapid and reliable tool for the detection of small differences in the target DNA sequences of closely related species.
The identification of indigenous AAB has critical importance to improve the process control, overcome unpredictable fermentation problems and select the most suitable strains as the potential starter culture. Therefore, in this study, we aimed to detect and compare AAB populations in grape and apple vinegar and in mother of vinegar samples obtained from different regions of Turkey. Thus the culture-independent PCR-DGGE technique was combined with culture-dependent molecular techniques, including (GTG) 5 -rep-PCR and sequence analysis of the 16S rRNA gene, 16S–23S rRNA internal transcribed sequences (ITS) region and tuf gene for identification and characterization of AAB isolated from analyzed samples. Furthermore, real-time PCR intercalating dye-based analysis was applied to AAB isolates to obtain species-level discrimination.