Abstract: Bifidocin A is a novel bacteriocin produced by Bifidobacterium animalis BB04 with antimicrobial activity against a wide range of foodborne bacteria. The objective of this study was to investigate the quorum-sensing regulation behavior of bifidocin A production in B. animalis BB04. The correlation between cell density and bacteriocin production was analyzed by monitoring the cell growth and bacteriocin antimicrobial activity during the fermentation process. Using a low bacteriocin culture model system, the presence of auto-inducing peptide and quorum-sensing system related to bacteriocin production were analyzed. The auto-inducing peptide was purified by ultrafiltration, Sephadex G25 chromatography and HPLC, and its molecular mass was determined by matrix-assisted laser desorption/ionization time of flight-mass spectrometry (MALDI-TOF-MS). Results showed that bifidocin A began to be synthesized when the cell density reached 7.31 (lg (CFU/mL)), and the bacteriocin production depended on cell density. In the low bacteriocin culture model system, the culture temperature was 37 ℃, the initial pH value of culture medium was 5, the concentration of culture medium was 1/10 modified MRS, the inoculum quantity was 1%, and the incubation time was 24 h. The auto-inducing peptide was detected in the fermentation supernatant and it mediated the regulation of bacteriocin production by the quorum-sensing system. The molecular mass of the purified auto-inducing peptide was 3 587.253 Da.

Key words: bacteriocin, Bifidobacterium spp., quorum-sensing, auto-inducing peptide, production, regulation