Novel bacteriocin produced by Lactobacillus alimentarius FM-MM4 from a traditional Chinese fermented meat Nanx Wudl: Purification,identification and antimicrobial characteristics

The present study aims to purify and characterize a novel bacteriocin (designated as lactocin MM₄) produced by Lactobacillus alimentarius FM-MM₄, which was isolated from Nanx Wudl, a traditional Chinese fermented meat. Lactocin MM₄ was extracted by ethyl acetate and purified through cation exchange chromatography and semi-preparative high-performance liquid chromatography (RP-HPLC). As revealed by LC-MS/MS, lactocin MM₄ has a molecular mass of 1104.58 Da with the N-terminal sequence QGVGPLGQGHR, demonstrating low homology with previously reported class II bacteriocins. Lactocin MM₄ exhibited broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative food-borne pathogens, as well as several yeasts. It was considerably thermo-stable with 84.7% residual antimicrobial activity after exposure to121 °C for 15 min, and it was highly stable at acidic pH (2–5). Proteases, such as trypsin, protease K, papain and pepsin, could completely inactivate the bacteriocin, while other enzymes, such as lipase and amylase, had no effect on its antimicrobial activity. These results indicate the potential of lactocin MM₄ for application in food preservation.