Bacteriocin-like inhibitory Substance (BLIS) Produced by Lactococcus lactis strain FA4 with Potential for Use in Aquaculture

Abstract

Lactococcus lactis is a lactic acid bacteria isolated from dairy environment which is considered as generally regarded as safe (GRAS). A L. lactis strain FA4 was previously isolated from Black tip shark have shown antagonistic properties against Vibrio parahaemolyticus, a shrimp and fish pathogen. In this study, cell free supernatant (CFS) from L. lactis FA4 has shown active antagonism against the growth of indicator strain V. parahaemolyticus, but not against V. alginolyticus. With V. parahaemolyticus, the minimum inhibitory concentration (MIC) recorded around 0.125AU/ml. The CFS component was found to be rather stable during brief heat treatment, retaining ~86% of residual activity, and alkaline treatment had retained ~60.8% of residual activity. SDS page analysis and zymogram studies revealed that the CFS contains proteinaceous substance that have molecular weight of approximately ~3-5kDa. Based on several previous studies, L. lactis strain FA4 produces a bacteriocin like substance (BLIS) that highly resembles to that of nisin. Therefore, the BLIS has future potential to be utilized as antimicrobial agent suitable to be used in aquaculture treatment.