Purification and characterization of plantaricin K-2 from Lactiplantibacillus plantarum K-2 isolated from locally fermented cabbage

Bacteriocins are considered to be safe food preservatives, which have great potential to replace antibiotics due to their high efficacy against multidrug-resistant pathogens. In this work, the bacteriocin plantaricin K-2 was purified by three-stage purification – cation exchange chromatography, hydrophobic chromatography, and reversed-phase high-performance liquid chromatography with the purpose of establishing its practical value. The molecular weight of the peptide was 3937.05 Da by mass spectrometric analysis (Quadrupole Time-of-Flight mass spectrometry). The bacteriocin plantaricin K-2 was identified to belong to Class IIa and its physico-biochemical parameters were determined, and the 16S ribosomal DNA sequence analysis confirmed that the strain synthesizing it was Lactiplantibacillus plantarum. Plantaricin K-2 did not show antimicrobial activity when treated with proteases, but showed high thermal stability at high temperatures (121°C, 30 min). Production of plantaricin K-2 reached 6400 AU/mL during the stationary growth phase of L. plantarum K-2 cultivated in MRS at 37°C for 48 h. Although plantaricin K-2 is usually classified as a narrow-spectrum Class IIa bacteriocin, it showed relatively broad activity against food microbes and pathogenic microorganisms. The results of the study show that plantaricin K-2, belonging to a Class IIa bacteriocin, is a promising natural and safe biological object that could be used for preserving food as an antibiotic-resistant means in clinical applications.

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