Isolation,Identification and Antibacterial Properties of Antimicrobial Lipopeptide from Bacillus coagulans XZQ-16

The aim of the study was to purify and identify antibacterial lipopeptide produced by Bacillus coagulans XZQ-16 and to explore the functional characteristics in anti-spoilage bacteria. The antibacterial lipopeptide was isolated and purified by acid precipitation,column chromatography on silica gel and Sephadex LH-20. Lipopeptide compounds were identified by using Fourier infrared spectroscopy(FT-IR)and reversed phase high performance liquid chromatography(RP-HPLC)techniques. The results showed that three flow fractions obtained by silica gel column chromatography had significant antibacterial activity. Four elution peaks were isolated by Sephadex LH-20 chromatography,among which,elution peak Ⅲ had significant antibacterial activity. FT-IR analysis confirmed that the purified antibacterial substance contained lipopeptide compounds. RP-HPLC further identified the presence of three components in the isolated antimicrobial substances,and identified the two groups as homologues of iturin and surfactin compared with the standard sample. The purified antimicrobial lipopeptide was stable over a broad pH range(4.0~12.0)and at temperatures up to 120 ℃ for 30 min. Antibacterial lipopeptide could inhibit the growth of a broad range of foodborne Gram-positive bacteria,including Bacillus cereus,Staphylococcus aureus,Listeria monocytogenes,Micrococcus luteus and Gram-negative bacteria such as E. Coli,Salmonella,Shigella and Pseudomonas aeruginosa. Moreover,unlike commercially available nisin and polymyxin B,which only worked on bacteria,the lipopeptide produced by strain XZQ-16 also inhibited fungi such as Candida albicans,Pichia pastoris and Aspergillus niger.Lipopeptide produced by Bacillus pumilus XZQ-16 showed high stability and broad antibacterial activity.This paper lays a theoretical foundation for its application in the fields of food,animal husbandry,medicine,cosmetics and plant protection.