The V7–V8 region of the 16S rDNA was amplified by using DNA isolated from each vinegar and mother of vinegar sample. The primers WBAC1 (5′-GTC GTC AGC TCG TGT CGT GAG A-3′) and WBAC2 (5′-CCC GGG AAC GTA TTC ACC GCG-3′) were used to amplify an approximately 328 bp fragment of the target region (Lopez et al., 2003). A GC clamp (5′-CGC CCG CCG CGC CCC GCG CCC GGC CCG CCG CCC CCG CCC C-3′) was attached to the WBAC1 primer, according to Lopez et al.(2003). All of the PCR amplifications were performed in a final volume of 50 μl, containing 25 μl of commercial PCR master mix (Dream Taq , Fermentas , USA), 40 pmol of forward primer with a GC clamp, 20 pmol of reverse primer and 100 ng sample DNA. The thermal cycler (TC-5000 gradient thermal cycler, Techne, UK) conditions were programmed in accordance with De Vero et al. (2006). The amplification products were checked by electrophoresis in 2% (w/v) agarose gel containing ethidium bromide and visualized under UV light. The sequence specific separation of the PCR products was performed on the Dcode TM Universal Mutation