Abstract: Objective: The bacteriocin-producing strain QF01, isolated from water kefir grains, was identified and the antibacterial activity of bacteriocin from the isolate was evaluated. The gene sequences encoding bacteriocin were analyzed as well. Methods: The antibacterial activity of bacteriocin was determined by the Oxford cup method. The bacteriocin-related genes were amplified by PCR, 16S rDNA analysis was used for bacterial identification and bacteriocin gene analysis was carried out by using online software (ProParam tool, TMHMM 2.0, InterProScan, SOPM and SWISS-MODEL). Results: Bacteriocin produced by strain QF01 demonstrated a strong inhibitory activity against Escherichia coli JM109. This strain was identified as Lactobacillus plantarum based on its 16S rDNA sequence. The four bacteriocin-encoding genes plnD, plnEF, plnV and plnR were found in Lactobacillus plantarum QF01. The plnV gene encoding product had a helical transmembrane structure with signal peptide characteristics at its N-terminal. In addition, each of the four gene encoding products contained α-helix, β-turn, extended chain and random coil structures, as predicted from the tertiary structure model. Conclusion: L. plantarum QF01 contains the bacteriocin-encoding genes plnD, plnEF, plnV and plnR, and has a strong inhibitory activity against E. coli.

Key words: Lactobacillus plantarum, bacteriocin, antibacterial activity, gene cloning, bioinformatics