title: Mechanisms of tolerance and high degradation capacity of the herbicide mesotrione by Escherichia coli strain DH5-α.
abstract: The intensive use of agrochemicals has played an important role in increasing agricultural production. One of the impacts of agrochemical use has been changes in population structure of soil microbiota. The aim of this work was to analyze the adaptive strategies that bacteria use to overcome oxidative stress caused by mesotrione, which inhibits 4-hydroxyphenylpyruvate dioxygenase. We also examined antioxidative stress systems, saturation changes of lipid membranes, and the capacity of bacteria to degrade mesotrione. Escherichia coli DH5-á was chosen as a non-environmental strain, which is already a model bacterium for studying metabolism and adaptation. The results showed that this bacterium was able to tolerate high doses of the herbicide (10× field rate), and completely degraded mesotrione after 3 h of exposure, as determined by a High Performance Liquid Chromatography. Growth rates in the presence of mesotrione were lower than in the control, prior to the period of degradation, showing toxic effects of this herbicide on bacterial cells. Changes in the saturation of the membrane lipids reduced the damage caused by reactive oxygen species and possibly hindered the entry of xenobiotics in the cell, while activating glutathione-S-transferase enzyme in the antioxidant system and in the metabolizing process of the herbicide. Considering that E. coli DH5-α is a non-environmental strain and it had no previous contact with mesotrione, the defense system found in this strain could be considered non-specific. This bacterium system response may be a general adaptation mechanism by which bacterial strains resist to damage from the presence of herbicides in agricultural soils.
authors.affiliation: Universidade Estadual de Ponta Grossa, UEPG, Departamento de Biologia Estrutural, Molecular e Genética, Ponta Grossa, PR, Brazil.
authors.forename: Luiz R
authors.initials: LR
authors.lastname: Olchanheski
authors.affiliation: Escola Superior de Agricultura Luiz de Queiroz, ESALQ, Universidade de São Paulo, USP, Piracicaba, SP, Brazil.
authors.forename: Manuella N
authors.initials: MN
authors.lastname: Dourado
authors.affiliation: Universidade Estadual de Ponta Grossa, UEPG, Departamento de Ciências Farmacêuticas, Ponta Grossa, PR, Brazil.
authors.forename: Flávio L
authors.initials: FL
authors.lastname: Beltrame
authors.affiliation: Programa de Pós-Graduação em Engenharia de Alimentos, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors.forename: Acácio A F
authors.initials: AA
authors.lastname: Zielinski
authors.affiliation: Universidade Estadual de Ponta Grossa, UEPG, Departamento de Engenharia de Alimentos, Ponta Grossa, PR, Brazil.
authors.forename: Ivo M
authors.initials: IM
authors.lastname: Demiate
authors.affiliation: Universidade Estadual de Ponta Grossa, UEPG, Departamento de Biologia Estrutural, Molecular e Genética, Ponta Grossa, PR, Brazil.
authors.forename: Sônia A V
authors.initials: SA
authors.lastname: Pileggi
authors.affiliation: Escola Superior de Agricultura Luiz de Queiroz, ESALQ, Universidade de São Paulo, USP, Piracicaba, SP, Brazil.
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Azevedo
authors.affiliation: Department of Soil, Water, and Climate, and BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, United States of America.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sadowsky
authors.affiliation: Universidade Estadual de Ponta Grossa, UEPG, Departamento de Biologia Estrutural, Molecular e Genética, Ponta Grossa, PR, Brazil.
authors.forename: Marcos
authors.initials: M
authors.lastname: Pileggi
mesh_terms: D000975:Antioxidants / Q000502:physiology; D001673:Biodegradation, Environmental; D003512:Cyclohexanones / Q000493:pharmacokinetics*; D004352:Drug Resistance, Microbial; D004361:Drug Tolerance; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism*; D006540:Herbicides / Q000493:pharmacokinetics*; D015227:Lipid Peroxidation / Q000187:drug effects; D008563:Membrane Lipids / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000493:pharmacokinetics
chemical_list: D000975:Antioxidants; D003512:Cyclohexanones; D006540:Herbicides; D008563:Membrane Lipids; D012989:Soil Pollutants; C432907:mesotrione