Purification, characterization, and action mechanism of plantaricin DL3, a novel bacteriocin against Pseudomonas aeruginosa produced by Lactobacillus plantarum DL3 from Chinese Suan-Tsai

A novel bacteriocin produced by Lactobacillus plantarum DL3 isolated from Suan-Tsai, a traditional Chinese fermented cabbage, was designated as plantaricin DL3. It was purified by ethyl acetate extraction followed by gel filtration and high-performance liquid chromatography. The molecular weight of plantaricin DL3 was determined as 2149 Da by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis. The amino acid sequence of plantaricin DL3 was predicted to be VGPGAINAGTYLVSRELFER by MALDI-TOF-MS/MS. This bacteriocin exhibited broad-spectrum antibacterial activity against Gram-positive and Gram-negative bacteria, especially Pseudomonas aeruginosa, high thermal stability (15 min, 121 A degrees C) and narrow pH stability (pH 2.5-5.5). The mechanism of action of this bacteriocin was responsible for the disruption of cell wall, accompanied with the leakage of proteins. These results suggested that plantaricin DL3 has potential applications in the control of Pseudomonas spp. in aquatic products.