The aim of this study was to investigate the antimicrobial potential of 52 natural isolates of Lactobacillus casei/paracasei. The incidence of relevant genes encoding BacSJ (bacSJ2-8/bacSJ2-8i gene cluster), acidocin 8912 (acdT), ABC-transporter (abcT) and accessory protein (acc) was also studied. These genes were found to be widespread amongst the analyzed L. casei/paracasei strains. The bacSJ2-8/bacSJ2-8i gene cluster was present in 49 (94.23%) and acdT in 41 (78.85%) of the 52 tested

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... Forty of these strains (76.92%) harbored both analyzed genes. Interestingly, only 17 strains (32.69%) with the bacSJ2-8/bacSJ2-8i gene cluster and/or the acdT GENETIKA, Vol. 44, No.3, 661 -677, 2012 gene showed bacteriocin production. Strain L. paracasei BGNK1-62 contained the bacSJ2-8/bacSJ2-8i gene cluster, but did not produce bacteriocin BacSJ possibly due to absence of the abcT and acc genes. Hence, these genes were introduced into BGNK1-62 by transformation with constructed plasmid pA2A, after which BacSJ was produced. In addition, it was found that L. paracasei BGGR2-66 produced new bacteriocin designated as BacGR that was biochemically characterized and its Nterminal sequence was determined.