Detection and partial characterization of a broad-range bacteriocin produced by Lactobacillus plantarum (ATCC 8014)

Lactobacillus plantarum (ATCC 8014) was tested for production of antimicrobial compounds. This study demonstrates that the cell-free supernatant of L. plantarum is effective in inhibiting the growth of a wide range of Gram-positive and Gram-negative bacteria including, Staphylococcus aureus, Escherichia coli, Listeria innocua, and Pseudomonas aeruginosa. The inhibitory compound lost activity when heated to temperatures greater than 30°C and when subjected to pH changes that lowered the pH below 4 or above 5. In addition, the inhibitory protein was susceptible to digestion by various proteases. The apparent molecular weight based on SDS-PAGE analysis is 122 KDa. These findings support the idea that the inhibitory compound is a protein and can be considered a bacteriocin secreted from the Gram-positive bacterium L. plantarum.