Pseudomonas spp. was isolated from activated-sludge and found to be able to mineralize 3-chloroaniline (3-CA). This strain was tested for its ability to clean wastewater containing 3-CA upon inoculation in activated-sludge. To monitor its survival, the strain was chromosomally marked with the gfp gene and designated Agfp. After inoculation into a lab-scale semi continuous activated-sludge (SCAS) system, the inoculated strain maintained itself in the sludge at least 45 days and was present in the sludge flocs. After an initial adaptation period of 6 days, complete degradation of 3-CA was obtained during two weeks, while no degradation at all occurred in the non-inoculated control reactors. Upon further operation of the SCAS system, only 50 % 3-CA removal was observed. Denaturing Gradient Gel Electrophoresis (DGGE) of 16S rRNA genes revealed a dynamic change in the microbial community structure of the activated-sludge. The DGGE patterns of the non inoculated and the inoculated reactors evolved after 7 days to different clusters, which suggests an effect of strain inoculation on the microbial community structure. The results indicate that bioaugmentation, even with a strain originating from that ecosystem and able to effectively grow on a selective substrate, is not permanent and will probably require regular resupplementation.

Pseudomonas, gfp, chloroaniline, DGGE