Separation and identification of bacteriocin-producing Bifidobacterium from breast-fed infants faeces

Objective: Good bacteriocin- producing Bifidobacterium were obtained from 44 strains from breast- fed babies faeces. Method: These strains were primarily screened by agar diffusion test and screened again by eliminating the disturbances of the organic acids, hydrogen peroxides and strain cells and proteinase assay.Good strains obtained were identified.Results: The antimicrobial activity of the fermentation broth of good strains of BB04and BL-8 remained strong after eliminating the disturbances of the organic acids, hydrogen peroxides and strain cells.In addition, the activity was significantly enhanced after ammonium sulphate precipitation and dialysis and the bacteriocin lost activities after treated with proteinase K, pepsin and trypsin. The results indicated that the bacteriocin produced by strain BB04 and BL-8 worked as antibacterial substance whose nature was protein.What's more, the bacteriocin produced from strain BB04 and BL-8 had a broad inhibitory spectrum.They could both inhibit Listeria monocytogenes, Staphylococcusaereu, Bacillu coagulans and Escherichia coli. Finally, based on morphological, physiological and biochemical characteristics of API 20A anaerobic appraisal system and 16S rDNA gene sequence, strain BB04 was identified as Bifidobacterium animalis and BL-8 was identified as Bifidobacterium adolescentis.Conclusion: Good Bifidobacterium strains BB04 and BL- 8 producing broad spectrum bacteriocin were separated from breast- fed infants faeces and identified as Bifidobacterium animalis and Bifidobacterium adolescentis.