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Applied and Environmental Microbiology, July 2000, p. 2906-2913, Vol. 66, No. 7
Laboratory of Microbial Ecology and
Technology1 and Laboratory of
Microbiology,2 Ghent University, B-9000
Ghent, Belgium
Received 10 December 1999/Accepted 17 April 2000
A strain identified as Comamonas testosteroni I2 was
isolated from activated sludge and found to be able to mineralize
3-chloroaniline (3-CA). During the mineralization, a yellow
intermediate accumulated temporarily, due to the distal
meta-cleavage of chlorocatechol. This strain was tested for
its ability to clean wastewater containing 3-CA upon inoculation into
activated sludge. To monitor its survival, the strain was chromosomally
marked with the gfp gene and designated I2gfp.
After inoculation into a lab-scale semicontinuous activated-sludge (SCAS) system, the inoculated strain maintained itself in the sludge
for 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 2 weeks, while no degradation at all occurred in the
noninoculated control reactor. 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 noninoculated 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.
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Bioaugmentation of Activated Sludge by an
Indigenous 3-Chloroaniline-Degrading Comamonas
testosteroni Strain, I2gfp
*
Corresponding author. Mailing address: Ghent
University, Faculty of Agricultural and Applied Biological Sciences,
Laboratory of Microbial Ecology and Technology, Coupure Links 653, B-9000 Ghent, Belgium. Phone: 32 (0)9 264 59 76. Fax: 32 (0)9 264 62 48. E-mail: Eva.Top{at}rug.ac.be.
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