CHARACTERIZATION OF AN ANTIMICROBIAL PEPTIDE PRODUCED BY LACTOBACILLUS CRISPATUS KLB46

초록

Human vagina harbors lactobacilli as normal flora which have been considered to play important roles in the health of vagina. They are known to secrete inhibitory substances to prevent vaginal infection by pathogenic organisms. In a previous study, we isolated a number of lactobacilli from Korean women and one of them (KLB46) was identified as Latobacillus crispatus by 16S rDNA sequencing. In this study, we found that L. crispatus KLB46 produced an antimicrobial peptide which was highly heat resistant. The maximum production of the peptide was found to occur during the stationary phase of the growth. From plasmid curing experiment we found that plasmid was not involved in the peptide production. In order to characterize the peptide, we carried out a series of purifications. L. crispatus KLB46 was grown for 15 h and removed by centrifugation and the peptide present in the supernatant fraction was concentrated by adding 80% ammonium sulfate. The precipitate pelleted by centrifugation was dissolved in 20mM sodium phosphate buffer, dialyzed against same buffer, and ultra-filtered. The concentrated sample was applied to a CM cation-exchange column before being eluted in 20mM sodium phosphate buffer with 1M NaCl. Fractions showing antimicrobial activity were collected and applied to an SDS-PAGE to estimate molecular mass. Further studies are underway to characterize the peptide.