Bioactivity Auantification of A Novel Antimicrobial Peptide by Agar Diffusion Bioassay

摘要

Recently, antimicrobial peptides (AMP) produced by bacteria, called bacteriocins, have attracted a great deal of attention as biopreservatives in the application of agri-food industry. Extensive industrial uses and research studies require an accurate and precise method for the quantification of novel AMP in food samples, fermentation broth-and other media. In this work, an agar diffusion bioassay was developed for the rapid, accurate and precise quantification of a novel AMP produced'by Brevibacillus laterosporus. The pre-diffusion step resulted in larger inhibition zones and more precise results, and the best combination was the method using Staphyloccocus aureus as an indicator strain with pre-diffusion at 4 ℃ for 12 h. To determine the activity units per millilitre of unknown bacteriocin (AU/ml), serial dilutions of the filter-sterilized supernatant were performed. The relationship between the bacteriocin concentration and the resulting zone of inhibition was demostrated and a high correlation coefficient (R2=0.9886) was obtained. This method may be also applied for the quantification of unknown bacteriocin.