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Applied and Environmental Microbiology, September 1998, p. 3368-3375, Vol. 64, No. 9
Departments of
Microbiology1 and
Agronomy,
Received 9 March 1998/Accepted 1 July 1998
We examined the ability of a soil bacterium, Agrobacterium
radiobacter J14a, to degrade the herbicide atrazine under a
variety of cultural conditions, and we used this bacterium to increase the biodegradation of atrazine in soils from agricultural chemical distribution sites. J14a cells grown in nitrogen-free medium with citrate and sucrose as carbon sources mineralized 94% of 50 µg of
[14C-U-ring]atrazine ml
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Biodegradation of Atrazine by Agrobacterium
radiobacter J14a and Use of This Strain in Bioremediation of
Contaminated Soil

and
1 in
72 h with a concurrent increase in the population size from 7.9 × 105 to 5.0 × 107 cells
ml
1. Under these conditions cells mineralized the
[ethyl-14C]atrazine and incorporated approximately 30%
of the 14C into the J14a biomass. Cells grown in medium
without additional carbon and nitrogen sources degraded atrazine, but
the cell numbers did not increase. Metabolites produced by J14a
during atrazine degradation include hydroxyatrazine, deethylatrazine,
and deethyl-hydroxyatrazine. The addition of 105 J14a cells
g
1 into soil with a low indigenous population of atrazine
degraders treated with 50 and 200 µg of atrazine g
1
soil resulted in two to five times higher mineralization than in
the noninoculated soil. Sucrose addition did not result in significantly faster mineralization rates or shorten degradation lag
times. However, J14a introduction (105 cells
g
1) into another soil with a larger indigenous
atrazine-mineralizing population reduced the atrazine degradation lag
times below those in noninoculated treatments but did not generally
increase total atrazine mineralization.
*
Corresponding author. Mailing address: USDA-ARS,
National Soil Tilth Laboratory, 2150 Pammel Dr., Ames, IA 50011-4420. Phone: (515) 294-2308. Fax: (515) 294-8125. E-mail:
moorman{at}nstl.gov.
Present address: Betz-Dearborn, Inc., Woodlands, TX 77380.
Present address: Department of Environmental Studies, Florida
International University, University Park, Miami, FL 33199.
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