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Keywords:

  • ammonium sulphate fractionation;
  • Bacillus licheniformis ;
  • bacteriocin;
  • electroelution;
  • Gram positive;
  • mass spectrometry;
  • thermostable

Abstract

Aim

To isolate and characterize bacteriocin, BL8, from the bacteria identified as Bacillus licheniformis from marine environment.

Methods and Results

One-hundred and twelve bacterial isolates from sediment and water samples collected off the coast of Cochin, India, were screened for antibacterial activity. Strain BTHT8, identified as Bacillus licheniformis, inhibited the growth of Gram-positive test organisms. The active component labelled as bacteriocin BL8 was partially purified by ammonium sulphate fractionation and was subjected to glycine SDS-PAGE. The band exhibiting antimicrobial activity was electroeluted and analysed using MALDI-TOF mass spectrometry, and the molecular mass was determined as 1·4 kDa. N-terminal amino acid sequencing of BL8 gave a 13 amino acid sequence stretch. Bacteriocin BL8 was stable even after boiling at 100°C for 30 min and over a wide pH range of 1–12.

Conclusion

A novel, pH-tolerant and thermostable bacteriocin BL8, active against the tested Gram-positive bacteria, was isolated from Bacillus licheniformis.

Significance and Impact of the Study

This study reports a stable, low molecular weight bacteriocin from Bacillus licheniformis. This bacteriocin can be used to address two important applications: as a therapeutic agent and as a biopreservative in food processing industry.