Polymerase chain reaction and denaturing gradient gel electrophoresis monitoring of fecal <i>Bifidobacterium</i> populations in a prebiotic and probiotic feeding trial

A culture-independent approach based on genus-specific PCR and denaturing gradient gel electrophoresis (DGGE) was used to monitor qualitative changes in fecal bifidobacterial communities in a human feeding trial. DNA was extracted directly from feces and bifidobacterial 16S rDNA sequences were amplified using genus-specific PCR. The PCR fragments were subsequently separated in a sequence-specific manner by DGGE in order to obtain a profile of bifidobacterial fragments. The DGGE profiles revealed that in general, administration for two weeks of galactooligosaccharide and/or Bifidobacterium lactis Bb-12 (8 g and 3 × 1010 cfu per day, respectively) did not affect the qualitative composition of the indigenous Bifidobacterium population, while B. lactis Bb-12 transiently colonised the gut