Purification and characterization of antimicrobial substances from Bacillus licheniformis BFP011

Bacillus licheniformis BFP011 isolated from papaya (Thailand) could produce extracellular antimicrobial substances which were active against some important phytopathogens, pathogenics and spoilage microorganisms such as Colletotrichum capsici, Escherichia coli O157: H7 and Salmonella typhi ATCC 5784. The antimicrobial substances of this bacterium showed resistance to pronase enzyme and high temperature at 100 and 121°C for 15 min. They were purified by TLC on silica gel plates F254 using the different solvent mixtures. The best solvent mixture was revealed as n-butanol: ethanol: acetic acid: water (30: 60: 5: 30, v/v). The spots F4, F5 and F6 from TLC were able to inhibit growth of S. typhi ATCC 5784 assayed in vitro by the disc diffusion method. The characterization of the active fractions F4, F5 and F6 from TLC and reversedphase HPLC indicated that the antimicrobial substances of B. licheniformis BFP011 contain peptides and unsaturated fatty acids.