Search results for "ATRAZINE"

Microbial aspects of atrazine biodegradation in relation to history of soil treatment

1999

Among 15 soils with different cropping practices, seven which had an history of repeated atrazine applications showed accelerated degradation of this herbicide. By contrast, grassland or agricultural soils with no recorded atrazine application, at least for the last three years, had a low degradation potential. No direct relation was found between the rate of atrazine mineralisation and the size of the microbial biomass. In adapted soils, the amounts of extractable residues were lowered and the very high percentages of radioactivity from [ring-14C]atrazine recovered as [14C]carbon dioxide demonstrated that N-dealkylation and deamidation were the only processes for micro-organisms to derive …

Monitoring of atrazine treatment on soil bacterial, fungal and atrazine-degrading communities by quantitative competitive PCR

2003

We report the development of quantitative competitive (QC) PCR assays for quantifying the 16S, 18S ribosomal and atzC genes in nucleic acids directly extracted from soil. QC-PCR assays were standardised, calibrated and evaluated with an experimental study aiming to evaluate the impact of atrazine application on soil microflora. Comparison of QC-PCR 16S and 18S results with those of soil microbial biomass showed that, following atrazine application, the microbial biomass was not affected and that the amount of 16S rDNA gene representing 'bacteria' increased transitorily, while the amount of 18S rDNA gene representing fungi decreased in soil. In addition, comparison of atzC QC-PCR results wit…

Alachlor and Bentazone Losses from Subsurface Drainage of Two Soils

2004

International audience; Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) is frequently detected at high concentrations in ground water. Bentazone [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] plus alachlor (2-chloro-2',6'-diethyl-N-methoxymethylacetanilide) is a potential herbicide combination used as a substitute for atrazine. Thus, the objective of this study was to assess the environmental risk of this blend. Drainage water contamination by bentazone and alachlor was assessed in silty clay (Vertic Eutrochrept) and silt loam (Aquic Hapludalf) soils under the same management and climatic conditions. Drainage volumes and concentrations of alachlor and bent…

[div]Long-term dynamics of the atrazine mineralization potential in surface and subsurface soil in an agricultural field as a response to atrazine ap…

2012

Abstract The dynamics of the atrazine mineralization potential in agricultural soil was studied in two soil layers (topsoil and at 35–45 cm depth) in a 3 years field trial to examine the long term response of atrazine mineralizing soil populations to atrazine application and intermittent periods without atrazine and the effect of manure treatment on those processes. In topsoil samples, 14 C-atrazine mineralization lag times decreased after atrazine application and increased with increasing time after atrazine application, suggesting that atrazine application resulted into the proliferation of atrazine mineralizing microbial populations which decayed when atrazine application stopped. Decay …

Mécanismes d'évolution de pseudomonas sp. adp sous pression de sélection exercée par l'atrazine

2010

L’atrazine est un pesticide qui est largement utilisé dans le monde depuis une quarantaine d’années. Son application répétée aaboutit non seulement à la contamination des eaux mais également à l’apparition de bactéries telluriques capables d’utiliserce xénobiotique comme source d’azote pour leur croissance. La caractérisation des gènes atz responsables de la dégradationde cette molécule a révélé qu’ils étaient largement dispersés et très conservés au sein du monde bactérien traduisant ainsid’une évolution et d’une dispersion récente de ces gènes, probablement concomitantes avec l’application d’atrazine dansl’environnement

Importance of genetic plasticity for microbial adaptation to pesticide biodegradation: in vitro evolution of Pseudomonas sp. ADP under atrazine or cy…

2011

International audience

Etude des mécanismes à l'origine de la dispersion des gènes codant les enzymes responsables de la minéralisation de l'atrazine au sein de la microflo…

2006

Le partage des tâches favorise la coexistence dans les communautés bactériennes dégradant l’atrazine

2019

National audience; Les communautés microbiennes exercent un rôle primordial dans la dégradation des xénobiotiques1, et en particulier des pesticides. Dans le cas de l’herbicide atrazine, plusieurs études ont démontré que sa dégradation faisait intervenir un consortium, plutôt qu’une espèce isolée2,3,4. Cependant, on ne sait pas comment la mise en place de ces consortiums dégradants se fait dans la nature. La théorie de la Reine Noire formalise les conditions nécessaires pour le mise en place de dépendance entre espèces5 : un membre de la communauté, appelé « helper », fournit un bien commun à la communauté par la dégradation d’un composé complexe, alors que les autres, appelés « beneficiari…

Evidence of atrazine mineralization in a soil from the Nile Delta: Isolation of Arthrobacter sp. TES6, an atrazine-degrading strain

2011

International audience; The s-triazine herbicide atrazine was rapidly mineralized (i.e., about 60% of C-14-ring-labelled atrazine released as (CO2)-C-14 within 21 days) by an agricultural soil from the Nile Delta (Egypt) that had been cropped with corn and periodically treated with this herbicide. Seven strains able to degrade atrazine were isolated by enrichment cultures of this soil. DNA fingerprint and phylogenetic studies based on 165 rRNA analysis showed that the seven strains were identical and belonged to the phylogeny of the genus Arthrobacter (99% similarity with Arthrobacter sp. AD38, EU710554). One strain, designated Arthrobacter sp. strain TES6, degraded atrazine and mineralized…

Atrazine uptake, elimination, and bioconcentration by periphyton communities and Daphnia magna: effects of dissolved organic carbon.

2001

The bioconcentration and toxicokinetics of atrazine in three different periphyton communities and in laboratory reared Daphnia magna were studied in natural and artificial waters with different dissolved organic carbon (DOC) concentrations and qualities. The exposure concentrations were similar to those short-lived peak concentrations found in contaminated waters. Atrazine uptake and elimination were very fast, and the bioconcentration was low both in periphyton and D. magna. The bioconcentration factors in D. magna were approx. 16% of those in periphyton. The uptake and elimination rates were also higher in periphyton than in Daphnia. The periphyton properties affected the bioconcentration…