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Field‐scale remediation of atrazine‐contaminated soil using recombinant Escherichia coli expressing atrazine chlorohydrolase
Author(s) -
Strong Lisa C.,
McTavish Hugh,
Sadowsky Michael J.,
Wackett Lawrence P.
Publication year - 2000
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1046/j.1462-2920.2000.00079.x
Subject(s) - atrazine , biostimulation , bioaugmentation , environmental remediation , bioremediation , biodegradation , escherichia coli , microbiology and biotechnology , biology , microorganism , environmental chemistry , contamination , bacteria , pesticide , chemistry , agronomy , ecology , biochemistry , genetics , gene
We performed the first field‐scale atrazine remediation study in the United States using chemically killed, recombinant organisms. This field study compared biostimulation methods for enhancing atrazine degradation with a novel bioaugmentation protocol using a killed and stabilized whole‐cell suspension of recombinant Escherichia coli engineered to overproduce atrazine chlorohyrolase, AtzA. AtzA dechlorinates atrazine, producing non‐toxic and non‐phytotoxic hydroxyatrazine. Soil contaminated by an accidental spill of atrazine (up to 29 000 p.p.m.) supported significant populations of indigenous microorganisms capable of atrazine catabolism. Laboratory experiments indicated that supplementing soil with carbon inhibited atrazine biodegradation, but inorganic phosphate stimulated atrazine biodegradation. A subsequent field‐scale study consisting of nine (0.75 m 3 ) treatment plots was designed to test four treatment protocols in triplicate. Control plots contained moistened soil; biostimulation plots received 300 p.p.m. phosphate; bioaugmentation plots received 0.5% (w/w) killed, recombinant E. coli cells encapsulating AtzA; and combination plots received phosphate plus the enzyme‐containing cells. After 8 weeks, atrazine levels declined 52% in plots containing killed recombinant E. coli cells, and 77% in combination plots. In contrast, atrazine levels in control and biostimulation plots did not decline significantly. These data indicate that genetically engineered bacteria overexpressing catabolic genes significantly increased degradation in this soil heavily contaminated with atrazine.