Bacteriocin activity of various iranian honey-associated bacteria and development of a simple medium for enhanced bacteriocin activity

Purpose Honey is a promising source of bacterial strains producing metabolites with antimicrobial activity. There is a great variety in the antimicrobial activity of honey from different areas of nature. Therefore, the aim of present study was to investigate the antibacterial activity of Iranian honey from different regions and to optimize the culture condition for the highly potent bacterial isolate. Methods Honey samples were collected from ten different regions of Iran and were screened for bacteriocin-producing bacteria. The best bacteriocin-producing strain was characterized and identified by 16S rDNA analysis. One-factor-at-a-time method was used for optimization of culture medium and the yield and time-course of bacteriocin production were compared in both shake flask and bio-reactor. Results The Bacillus subtilis SB1 that was isolated from Sabalan honey showed potent antibacterial activity with prominent thermal stability. The optimum medium for the bacteiocin production was a yeast extract-based medium. The optimum incubation temperature for bacteriocin production was 34 degrees C. Bacteriocin production was higher near neutral pH conditions than that produced at acidic or alkaline environment. The results of cell growth and bacteriocin assays revealed that the exponential phase of growth and antibacterial compounds production was started rapidly in bioreactor than flask. Conclusions Findings of this study supported the folkloric application of honey against some infectious diseases. B.subtilis SB1 that isolated from Sabalan honey was a potential source for bacteriocins-like compounds. Our studies suggested a simple buffered nitrogen-based medium for SB1 growth and bacteriocin activity in both shake flask and bioreactor.

Automated summary

This study investigated the antibacterial activity of Iranian honey from different regions, identifying Bacillus subtilis SB1 from Sabalan honey as a potent source of antibacterial compounds. Optimal conditions for bacteriocin production were found to be a yeast extract-based medium at 34 degrees C with near neutral pH. Production of antibacterial compounds in bioreactor was found to be more rapid than in shake flask.