Two microbial communities were tested, one from the rhizosphere of potatoes, and the other from an activated sludge reactor fed with glucose and peptone. The DGGE/TGGE results showed the enrichment of specific bacterial populations in
the inocula of both communities. Enriched strains from the rhizosphere sample could not be found in the banding
pattern of the original inoculum, whereas the enriched strains from the activated sludge sample could be found in
its inoculum. Hybridization analysis of the DGGE / TGGE patterns indicated the enrichment of strains affiliated to
the y-subclass of the Proteobacteria that were dominant community members in the activated sludge reactor, but
only minor constituents of the rhizosphere microbial community.