FIG. 2.

DGGE profiles generated from gradient fractions (6-9) derived from RNA from activated sludge without amendment with ¹³C-labeled E. coli (A) and with amendment with ¹³C-labeled E. coli (B). Fractions 6 have the highest buoyant density, while fractions 9 have the lowest. Although the entire protozoan community appears to have acquired carbon from E. coli, the bands annotated 1 (Epicarchesium abrae, Ciliophora, Peritrichia, 97%), 2 (Spumella sp., Heterokontophyta, Ochromonadales, 98%), and 3 (Zoothamnium duplicatum, Ciliophora, Peritrichia, 96%) represent protozoa that have dominated the acquisition of carbon from E. coli. Band 4 (Hartmannella sp., Amoebozoa, Lobosea, 92%) represents an abundant community member that was not labeled.