Probiotics shown to change bacterial community structure in the avian gastrointestinal tract.

Culturing and molecular techniques were used to monitor changes in the bacterial flora of the avian gastrointestinal (GI) tract following introduction of genetically modified (GM) and unmodified probiotics. Community hybridization of amplified 16S ribosomal DNA demonstrated that the bacterial flora of the GI tract changed significantly in response to the probiotic treatments. The changes were not detected by culturing. Although both GM and non-GM strains of Enterococcus faecium NCIMB 11508 changed the bacterial flora of the chicken GI tract, they did so differently. Probing the community DNA with an Enterococcus faecalis-specific probe showed that the relative amount of E. faecalis in the total eubacterial population increased in the presence of the non-GM strain and decreased in the presence of the GM probiotic compared with the results obtained with an untreated control group.