Licheniocin 50.2 and Bacteriocins from Lactococcus lactis subsp. lactis biovar. diacetylactis BGBU1-4 Inhibit Biofilms of Coagulase Negative Staphylococci and Listeria monocytogenes Clinical Isolates

BACKGROUND Coagulase negative staphylococci (CoNS) and Listeria monocytogenes have important roles in pathogenesis of various genital tract infections and fatal foetomaternal infections, respectively. The aim of our study was to investigate the inhibitory effects of two novel bacteriocins on biofilms of CoNS and L. monocytogenes genital isolates. METHODS The effects of licheniocin 50.2 from Bacillus licheniformis VPS50.2 and crude extract of bacteriocins produced by Lactococcus lactis subsp. lactis biovar. diacetylactis BGBU1-4 (BGBU1-4 crude extract) were evaluated on biofilm formation and formed biofilms of eight CoNS (four S. epidermidis, two S. hominis, one S. lugdunensis and one S. haemolyticus) and 12 L. monocytogenes genital isolates. RESULTS Licheniocin 50.2 and BGBU1-4 crude extract inhibited the growth of both CoNS and L. monocytogenes isolates, with MIC values in the range between 200-400 AU/ml for licheniocin 50.2 and 400-3200 AU/ml for BGBU1-4 crude extract. Subinhibitory concentrations (1/2 × and 1/4 × MIC) of licheniocin 50.2 inhibited biofilm formation by all CoNS isolates (p < 0.05, respectively), while BGBU1-4 crude extract inhibited biofilm formation by all L. monocytogenes isolates (p < 0.01 and p < 0.05, respectively). Both bacteriocins in concentrations of 100 AU/mL and 200 AU/mL reduced the amount of 24 h old CoNS and L. monocytogenes biofilms (p < 0.05, p < 0.01, p < 0.001). CONCLUSIONS This study suggests that novel bacteriocins have potential to be used for genital application, to prevent biofilm formation and/or to eradicate formed biofilms, and consequently reduce genital and neonatal infections by CoNS and L. monocytogenes.