Environmental impact of synthetic and natural ß-triketone herbicides: detection, microbial adaptation, biodegradation and toxicity.

Most agricultural production relies on the use of chemicals to maintain high crop yields. The use of these chemicals in farming practices is viewed as an integral part of the success of the intensive farming. However, most of the pesticides applied to agricultural lands may affect non-target organisms and contaminate soil and water media. Increasing public concern about the impact of pesticides on the environment, and European legislation has led to develop some strategies to evaluate and to prevent the potential impacts of different land management practices.
In this context, new generations of less environmentally dangerous molecules, such as lower impact pesticides, biopesticides and natural product-based pesticides have been introduced. Despite this, a lot of work has to be carried out concerning several aspects of the development of these news substances and particularly to evaluate the possible risks and adverse effects of such compounds on environment and humans.
The TRICETOX project focuses on studying the ß-triketone herbicide family, a post-emergence maize selective herbicides belonging to this new generation of molecules which have been introduced on the market, in replacement of atrazine, banned in several European countries in 2003. Inside this family, four compounds will be studied in detail, two synthetic ones, i.e. sulcotrione and mesotrione and two natural ones i.e. leptospermome and myrigalone.
The TRICETOX project aims precisely to answer the following questions:
(1) How to develop analytical tools suitable for a high capacity monitoring of the ß-triketone herbicides in the framework of environmental risk assessment?
(2) What are the microbial genes coding for the catabolic enzymes involved in the bacterial biodegradation of ß-triketone herbicides? Are these genes regulated and how?
(3) Is ß-triketone biodegradation enough for their dissipation in the environment? Are those microorganisms and/or enzymes suitable for a potential bioremediation solution?
(4) Are the natural ß-triketone herbicides a safe alternative to synthetic ones?
The objectives of this project are: (i) to develop bioassays and biosensors as innovative and low cost analytical tools for the detection of the ß-triketone herbicides. (ii) to characterize the genetic system involved in the synthetic ß-triketone herbicide degradation pathways of the sulcotrione degrading strain Pseudomonas putida 1OP, and the mesotrione degrading strain Bacillus sp. 3B6. (iii) to focus on the natural ?-triketone herbicides by addressing their soil behaviour, by studying their impact on soil microbial communities with microcosm studies, by studying their biodegradation pathways and by testing the toxicity of these compounds and their degradation products. (iv) to communicate to scientific and general public, to contribute to higher education program, and to promote results towards industrial partners.
This innovating project will search for gaining new insights about the global environmental impact of the triketone herbicides, towards multidisciplinary scientific approaches, bringing together specialists from complementary disciplinary areas (microbial ecologists, biochemists, analytical chemists, and molecular biologists).
From an academic point of view, the expected results of this study will help in a better understanding of the fate and behaviour of those pesticides, and on the relevance of the natural triketone herbicides compared to their synthetic counterparts. The obtained results will undoubtedly lead to improving current knowledge and state-of-the-art in genetic characterisation of bacterial adaptation mechanisms, and to develop analytical innovative and competitive tools, suitable for environmental risk assessment.

ANR Programme: Contaminants et Environnements : Santé, Adaptabilité, Comportements et Usages (CESA) 2013

Project ID: ANR-13-CESA-0002

Project coordinator:
Lise BARTHELMEBS (Institut de Modélisation et d'Analyses en Environnement et Santé)
barthelm@univ-perp.fr

Scientific Manager UMR Agroécologie : Fabrice MARTIN-LAURENT