Optimization, characterization and partial purification of bacteriocin produced by Staphylococcus haemolyticus MSM an isolate from seaweed

There is an urgent need for the development of more effective and safe drug to curb the proliferation of aquaculture pathogens. Therefore, the present study was aimed to evaluate the antimicrobial potential of bacteriocin produced by seaweed associated bacterium and the potential strain was identified as Staphylococcus haemolyticus MSM by 16S rRNA sequencing. The optimum culture conditions for maximum bacteriocin production were detected at pH 9 and 30 °C. Subsequently, the cell density and bacteriocin production kinetics were also studied in Zobell marine (ZM) broth and it was inferred that the maximum cell growth and bacteriocin production were observed at 48 h and 2500 AU/ml respectively. The inhibitory property of the bacteriocin was analyzed by double layer and agar well diffusion assay. The activity of bacteriocin against Staphylococcus aureus was 23.6±0.63 mm, for Vibrio harveyi 22.6±0.42 mm whereas the positive control chloromphenical had 24.3±0.52 mm against V. harveyi. In contrast the antimicrobial activity of bacteriocin produced by S. haemolyticus MSM was inactivated by the addition of proteinase K, thus confirming the proteinaceous nature of the inhibition. Bacteriocin was heat tolerant and remained active after 1 h at 100 °C. Activity of bacteriocin was not affected by treatment with 1% Triton X-100, Tween 40, Tween 80, SDS, and EDTA. According to SDS-PAGE, the size of bacteriocin was approximately 8 kDa. This study clearly indicates that seaweed associated bacterium S. haemolyticus MSM and its bacteriocin could be effectively used in disease prevalence in the aquaculture industry.