title: Combined bioaugmentation and biostimulation to cleanup soil contaminated with high concentrations of atrazine.
abstract: We developed a joint bioaugmentation and biostimulation approach for the clean up of soil contaminated with high (168.7 and 337.4 microg g(-1)) concentrations of the herbicide atrazine (2-chloro-4-(ethylamino)-6-isopropylamino-s-triazine). Pseudomonas sp. strain ADP (P. ADP) was used for bioaugmentation (approximately 10(7) cells g(-1) soil), and citrate (concentration range 5.8-40 mg g(-1) soil) and succinate (6.2-30.8 mg g(-1)) were used for biostimulation. The study soil had indigenous potential for atrazine mineralization (54.4 +/- 2% of 168.7 microg g(-1) mineralized after 67 day), but rapid mineralization only took place after a prolonged acclimation phase (approximately 28 days). Inoculation with P. ADP alone resulted in a limited improvement in mineralization (e.g., 30.6 +/- 1% mineralization of 168.7 microg g(-1) of atrazine in inoculated soil cf. < 0.5% in noninoculated in 7 days). Quantification of surviving numbers of P. ADP revealed a 10-fold decline from initial levels. However, bioaugmentation together with citrate or succinate biostimulation markedly increased P. ADP cell survival and atrazine mineralization (e.g., addition of 11.6 mg g(-1) of citrate increased mineralization of 337.4 microg g(-1) of atrazine from < 2 to 79.9 +/- 1% in 13 days). A critical parameter in determining the extent of atrazine mineralization by P. ADP was C(s):N(atz) (soluble carbon to atrazine nitrogen ratio): C(s):N(atz) > 40 was required for maximal atrazine mineralization. We suggest our observations may be used as a framework for rational bioremediation of field soils contaminated with atrazine.
authors.affiliation: Biological Sciences Research Group, Centre for Biological and Chemical Engineering, Instituto Superior Técnico, Lisbon, Portugal.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Silva
authors.forename: Arsénio M
authors.initials: AM
authors.lastname: Fialho
authors.forename: Isabel
authors.initials: I
authors.lastname: Sá-Correia
authors.forename: Richard G
authors.initials: RG
authors.lastname: Burns
authors.forename: Liz J
authors.initials: LJ
authors.lastname: Shaw
mesh_terms: D001280:Atrazine / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019343:Citric Acid / Q000378:metabolism; D006540:Herbicides / Q000378:metabolism*; D011549:Pseudomonas; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D006540:Herbicides; D012989:Soil Pollutants; D019343:Citric Acid; D001280:Atrazine