Characterization, modes of action, and application of a novel broad-spectrum bacteriocin BM1300 produced byLactobacillus crustorumMN047

Bacteriocins are ribosomally synthesized peptides with antibacterial activity against food-borne pathogenic bacteria that cause spoilage, possessing important potential for use as a natural preservative in the food industry. The novel bacteriocin BM1300 produced byLactobacillus crustorumMN047 was identified after purification in this study. It displayed broad-spectrum antibacterial activity against some selected Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) values of BM1300 againstStaphylococcus aureusATCC 25923 andEscherichia coliATCC 25922 were 13.4 mu g/mL and 6.7 mu g/mL, respectively. Moreover, BM1300 showed excellent thermal (between 60 and 120 degrees C), pH (2-11), and chemical (Tween-40, Tween-80, Triton X-100, and EDTA) stabilities. Time-kill curves revealed that BM1300 exhibited bactericidal activity againstS.aureusandE.coli. The scanning and transmission electron microscopy indicated that BM1300 acted by disrupting the cell membrane integrity and increasing cell membrane permeabilization of indicator bacteria. The disruption of cell membrane integrity caused by BM1300 was further demonstrated by the uptake of propidium iodide (PI) and the release of intracellular lactate dehydrogenase (LDH) and nucleic acid and proteins. Moreover, BM1300 affected cell cycle distribution to exert antibacterial activity collaboratively. Meanwhile, BM1300 inhibited the growth ofS.aureusandE.coliof beef meat and improved the microbiological quality of beef meat. These findings place BM1300 as a potential biopreservative in the food industry.