Stability of the bacterial communities supported by a seven-stage biological process treating pharmaceutical wastewater as revealed by PCR-DGGE.

The stabilities of the bacterial community structures supported by seven full-scale biological reactors treating pharmaceutical wastewater were investigated by denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) amplified 16S rRNA gene fragments. Effluent quality from this treatment process was consistently high with respect to BOD5 (<30 mgl(-1)), soluble COD (<500 mgl(-1)), and total ammonia (< 5 mgl(-1) as N) concentrations. Long-term community structure stability was studied by comparing the similarity of PCR-DGGE fingerprints from samples collected 87 days apart between which the influent wastewater characteristics were relatively stable.