Effects of orally administeredLactobacillus caseiDN-114 001 on the composition or activities of the dominant faecal microbiota in healthy humans

Abstract

The composition and activities of the faecal microbiota in twelve healthy subjects analysed in a single open study were monitored before (1-week baseline step), during (10d supplementation step) and after (10d follow-up step) the ingestion of a fermented milk containingLactobacillus caseiDN-114001. Fluorescentin situhybridisation with group-specific DNA probes, real-time PCR usingL. paracaseigroup-specific primers and temporal temperature gradient gel electrophoresis (TTGE) using group-specific primers were carried out, together with bacterial enzyme activity and metabolite analyses to monitor the structure and activities of the faecal microbiota.L. caseiDNA was detected in the faeces of all of the subjects by TTGE after 10d supplementation. Its quantification by real-time PCR showed a 1000-fold increase during the test step compared with initial levels. No major modification in either the dominant members of the faecal microbiota or their activities was observed during the trial. In conclusion, the short-term consumption of a milk product containingL. caseiDN-114001 was accompanied by a high, transient increase in the quantity of this strain in the faeces of all of the subjects without markedly affecting biochemical or bacteriological factors.