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Appl Environ Microbiol, January 1998, p. 178-184, Vol. 64, No. 1
Department of Biochemistry,
Received 5 August 1997/Accepted 31 October 1997
Pseudomonas sp. strain ADP contains the genes,
atzA, -B, and -C, that encode three
enzymes which metabolize atrazine to cyanuric acid.
Atrazine-catabolizing pure cultures isolated from around the world
contain genes homologous to atzA, -B, and
-C. The present study was conducted to determine whether
the same genes are present in an atrazine-catabolizing bacterial
consortium and how the genes and metabolism are subdivided among member
species. The consortium contained four or more bacterial species, but
two members, Clavibacter michiganese ATZ1 and
Pseudomonas sp. strain CN1, collectively mineralized
atrazine. C. michiganese ATZ1 released chloride from atrazine, produced hydroxyatrazine, and contained a homolog to the
atzA gene that encoded atrazine chlorohydrolase. C. michiganese ATZ1 stoichiometrically metabolized hydroxyatrazine
to N-ethylammelide and contained genes homologous to
atzB and atzC, suggesting that either a
functional AtzB or -C catalyzed N-isopropylamine release from hydroxyatrazine. C. michiganese ATZ1 grew on
isopropylamine as its sole carbon and nitrogen source, explaining the
ability of the consortium to use atrazine as the sole carbon and
nitrogen source. A second consortium member, Pseudomonas
sp. strain CN1, metabolized the N-ethylammelide produced by
C. michiganese ATZ1 to transiently form cyanuric acid, a
reaction catalyzed by AtzC. A gene homologous to the atzC
gene of Pseudomonas sp. strain ADP was present, as
demonstrated by Southern hybridization and PCR. Pseudomonas
sp. strain CN1, but not C. michiganese, metabolized cyanuric acid. The consortium metabolized atrazine faster than did
C. michiganese individually. Additionally, the consortium metabolized a much broader set of triazine ring compounds than did
previously described pure cultures in which the atzABC
genes had been identified. These data begin to elucidate the genetic and metabolic bases of catabolism by multimember consortia.
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Molecular Basis of a Bacterial Consortium:
Interspecies Catabolism of Atrazine
*
Corresponding author. Mailing address: Department of
Biochemistry, Biological Processes Technology Institute, Center for
Biodegradation Research & Informatics, 240 Gortner Laboratories,
University of Minnesota, 1479 Gortner Ave., St. Paul, MN 55108-6106. Phone: (612) 625-3785. Fax: (612) 625-1700. E-mail:
wackett{at}biosci.cbs.umn.edu.
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