Izučavanje antimikrobnog potencijala prirodnih izolata Lactobacillus casei/paracasei grupe

Abstract

Cilj ove studije je izučavanje antimikrobnog potencijala 52 prirodna izolata vrste L. casei/paracasei. Učestalost gena koji kodiraju BacSJ (bacSJ2-8/bacSJ2-8i genski klaster), acidocin 8912 (acdT), ABC-transporter (abcT) i pomoćni protein (acc) su takođe izučavani. Genski klaster bacSJ2-8/bacSJ2-8i prisutan je kod 49 (94.23%), a acdT kod 41 (78.85%) od 52 testirana soja. Četrdeset sojeva (76.92%) poseduje oba analizirana gena. Interesantno je da samo 17 sojeva (32.69%) koji poseduju bacSJ2-8/bacSJ2-8i genski klaster i/ili acdT gen proizvode bakteriocine. Soj L. paracasei BGNK1-62 poseduje bacSJ2-8/bacSJ2-8i genski klaster, ali ne proizvodi bakteriocin BacSJ što je verovatno posledica nedostatka abcT i acc gena. Nakon transformacije soja BGNK1-62 konstruktom pA2A koji poseduje abcT i acc gene ostvarena je proizvodnja bakteriocina BacSJ. Osim toga, utvrđeno je da soj L. paracasei BGGR2-66 proizvodi nov bakteriocin označen kao BacGR, koji je biohemijski okarakterisan, a određena je i njegova N-terminalna sekvenca.

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 strains. 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 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 N- terminal sequence was determined.