Purification and characterization of a novel bacteriocin produced by Lactobacillus crustorum MN047 isolated from koumiss from Xinjiang, China.

The growing emergence of antibiotic-resistant bacteria in the food industry needs to be controlled with effective antimicrobials. In this study, bacteriocin MN047 A (BMA) was found to have antibacterial activity against multidrug-resistant bacteria. It was produced by Lactobacillus crustorum MN047, which was first isolated from koumiss, a traditional fermented dairy product from Xinjiang Autonomous Region, China. It was purified by ammonium sulfate precipitation, ion-exchange chromatography, and reversed-phase chromatography. It had a low molecular mass of 1,770.89 Da according to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and the sequence was identified as QLPWQILGIVAGMFQA by liquid chromatography-tandem mass spectrometry analysis and MASCOT searching. It was proteinaceous in nature: the bacteriocin was digested by protease but not by α-amylase or lipase. It showed broad pH toleration (pH 2-11), good thermostability, and good storage stability. It had a broad inhibitory spectrum, including both gram-positive and gram-negative bacteria. Growth curve and time-kill kinetics indicated that it was bactericidal to the indicator strains, and this finding was verified by scanning electron microscope and transmission electron microscope after treatment with BMA. As well, BMA halted the growth of Staphylococcus aureus and Escherichia coli in the G1 and G2/M phases according to cell-cycle analysis by flow cytometry, indicating that BMA had comprehensive inhibitory effects against foodborne pathogens.