Novel antilisterial bacteriocin licheniocin 50.2 from Bacillus licheniformis VPS50.2 isolated from soil sample

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.

Keywords: Bacillus licheniformis; bacteriocin; licheniocin 50.2; subclass II.3.