Purification and characterization of plantaricin SLG1, a novel bacteriocin produced by Lb. plantarum isolated from yak cheese

Abstract

Yak milk cheese is one of the most important foods for the Tibetan people. Lactobacillus plantarum SLG1 isolated from yak cheese was shown to produce a novel bacteriocin, plantaricin SLG1. Production of plantaricin SLG1 in MRS medium was maximized after 24 h incubation at 37 °C (the stationary phase of growth). An innovative method, namely magnetic liposome adsorption combined with reversed-phase high performance liquid chromatography (RP-HPLC), was developed to screen for and efficiently purify bacteriocin compounds from the cell free supernatants from Lb. plantarum SLG1. The molecular mass of plantaricin SLG1 is 1083.25 Da and its amino acid sequence Tyr-Gly-Asn-Gly-Val-Phe-Ser-Val-Ile-Lys was determined by N-sequencing. Analyses by Circular dichroism (CD) spectra and predicted 3D structure suggested that the peptide maintains a well-defined conformation. Plantaricin SLG1 exhibited a wide range of antimicrobial activity against many food-borne spoilage and pathogenic bacteria, as well as some fungi. Results using scanning electron microscopy indicated that the mode of action was bactericidal and plantaricin SLG1 was able to damage the cell membrane integrity ultimately causing pathogen lethality.