Purification, Identification, and Characterization of Surfactin from Bacillus velezensis 1-3

The antimicrobial substances produced by Bacillus velezensis 1-3, a strain with antibacterial activity isolated from oral samples, were separated and purified by ammonium sulfate precipitation, gel filtration chromatography and thin-layer chromatography and were analyzed by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS). These substances were identified as surfactin consisting of three cyclic lipopeptides with 14‒16 carbon atoms, whose molecular masses were 1030.642, 1044.660 and 1058.677 Da, respectively. Surfactin could function as a surfactant and exhibited good antimicrobial activity against common pathogenic bacteria in the food, medical and livestock industries. Meanwhile, the minimal inhibitory concentration (MIC) of surfactin against Listeria monocytogenes ATCC 19115 was 4 μg/mL. Surfactin did not show hemolytic activity against mouse red blood cells within the effective antibacterial concentration range. It could endure temperatures at 20‒100 ℃ and withstand a wide pH range of 2.0‒10.0. Hence, surfactin produced by B. velezensis 1-3 has great potential for applications in the food, medical, and livestock fields.