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Keywords:

  • Bacillus licheniformis ;
  • bacteriocin;
  • licheniocin 50.2;
  • subclass II.3

Abstract

Aim

To isolate and characterize bacteriocin, licheniocin 50.2, from soil bacteria identified as Bacillus licheniformis.

Methods and Results

The strain B. licheniformis VPS50.2 was identified as bacteriocin producer, effective against Gram-positive bacteria, including Listeria monocytogenes, methicillin-resistant Staphylococcus aureus (MRSA) and β-haemolytic streptococci. The start of bacteriocin production coincides with the beginning of sporulation. Ammonium sulfate precipitation, chloroform extraction and ultrafiltration were used for bacteriocin purification. MALDI TOF/TOF mass spectrometry of purified sample detected the protein with molecular mass of 3253·209 Da. N-terminal sequencing recognized first 15 amino acids with the sequence: W E E Y N I I X Q L G N K G Q. We named the newly characterized bacteriocin as subclass II.3 bacteriocin, licheniocin 50·2. The bacteriocin activity was insensitive to lysozyme and proteinase K, heat stable after incubation at 100°C for 30 min and over wide range of pH (2–12). MICs of crude bacteriocin extract were determined for L. monocytogenes and MRSA. Time–kill study showed that licheniocin had bactericidal effect to L. monocytogenes.

Conclusion

A novel, thermostable, pH-tolerant bacteriocin active against Gram-positive bacteria was isolated.

Significance and Impact of the Study

Attributes of new, stable licheniocin 50.2 make it a promising agent for application as biopreservative in food industry.