Determination of survival, identity and stress resistance of probiotic bifidobacteria in bio-yoghurts
Article first published online: 8 FEB 2006
Letters in Applied Microbiology
Volume 42, Issue 3, pages 189–194, March 2006
How to Cite
Jayamanne, V.S. and Adams, M.R. (2006), Determination of survival, identity and stress resistance of probiotic bifidobacteria in bio-yoghurts. Letters in Applied Microbiology, 42: 189–194. doi: 10.1111/j.1472-765X.2006.01843.x
- Issue published online: 8 FEB 2006
- Article first published online: 8 FEB 2006
- 2005/0468: received 30 April 2005, revised 27 July 2005 and accepted 8 November 2005
- acid tolerance;
- oxidative stress resistance;
Aims: To determine the level of bifidobacteria in bio-yoghurts in the UK, identify the species, and compare the resistance of common Bifidobacterium spp. to acidity and oxidative stress.
Methods and Results: A storage trial of bio-yoghurts was carried out to determine the level and survival of bifidobacteria. The 16S rRNA gene targeted PCR was used to identify the species. Acid tolerance was determined by introducing the organisms to pH-adjusted skimmed milk and enumerating during storage at 4°C. Oxidative stress resistance was determined using the H2O2 disc diffusion assay technique. Nine of 10 bio-yoghurts contained bifidobacteria at levels >106 CFU g−1 at the time of purchase. The viability of the organism decreased during storage and on expiry only five products retained viability >106 CFU g−1 while two others were very close to the target population. Bifidobacterium animalis ssp. lactis showed superior survival abilities and stress tolerance compared with Bifidobacterium longum, Bifidobacterium breve, Bifidobacterium bifidum, Bifidobacterium adolescentis and Bifidobacterium longum biotype infantis.
Conclusions: Bifidobacterium animalis ssp. lactis, the only Bifidobacterium spp. found in bio-yoghurts, had the greatest resistance to acidity and oxidative stress.
Significance and Impact of the Study: The technological properties of B. animalis ssp. lactis make it suitable for inclusion in bio-yoghurts although its putative health benefits need further investigation.