Isolation and identification of Komagataeibacter xylinus from Iranian traditional vinegars and molecular analyses

Acetic acid bacteria (AAB) are one of the major interests of researchers. Traditional vinegars are suitable sources of AAB because they are not undergone industrial process like filtering and adding preservatives. Komagataeibacter xylinus as a member of AAB is known as the main cellulose producer among other bacteria. The purpose of the current study was to isolate the bacteria from traditional vinegars and its molecular analyses.
Vinegar samples were collected. Well-organized bacteriological tests were carried out to differentiate isolated bacteria from other cellulose producers and to identify K. xylinus. NaOH treatment and Calcofluor white staining were used for detecting cellulose. Chromosomal DNA of each strain was extracted via three methods of boiling, phenol-chloroform and sonication. Molecular analyses were performed on the basis of 16S rRNA sequences and cellulose synthase catalytic subunit gene (bcsA) for further confirmation. Phylogenetic tree was constructed for more characterization. Two housekeeping genes were studied including phenylalanyl-tRNA synthase alpha subunit (pheS) and RNA polymerase alpha subunit (rpoA).
Of the 97 samples, 43 K. xylinus strains were isolated. They were identified via bacteriological and molecular techniques. 16S rDNA sequence showed 99% similarity with registered sequences of the bacteria. Biodiversity of the genome confirmed by analyzing bcsA, pheS and rpoA genes.
K. xylinus can be isolated from traditional vinegars. Screening tests ought to include the classical methods and molecular techniques. Different molecular techniques and more genomic research should be developed to expand our knowledge for distinguishing isolated bacteria especially in the fields of AAB.