GST activity and membrane lipid saturation prevents mesotrione-induced cellular damage in Pantoea ananatis

Abstract

Callisto®, containing the active ingredient mesotrione (2-[4-methylsulfonyl-2-nitrobenzoyl]1,3-cyclohenanedione), is a selective herbicide that controls weeds in corn crops and is a potential environmental contaminant. The objective of this work was to evaluate enzymatic and structural changes in Pantoea ananatis, a strain isolated from water, in response to exposure to this herbicide. Despite degradation of mesotrione, probably due a glutathione-S-transferase (GST) pathway in Pantoea ananatis, this herbicide induced oxidative stress by increasing hydrogen peroxide production. Thiol fragments, eventually produced after mesotrione degradation, could be involved in increased GST activity. Nevertheless, there was no peroxidation damage related to this production, as malondialdehyde (MDA) synthesis, which is due to lipid peroxidation, was highest in the controls, followed by the mesotrione- and Callisto®-treated cultures at log growth phase. Therefore, P. ananatis can tolerate and grow in the presence of the herbicide, probably due an efficient control of oxidative stress by a polymorphic catalase system. MDA rates depend on lipid saturation due to a pattern change to a higher level of saturation. These changes are likely related to the formation of GST-mesotrione conjugates and mesotrione degradation-specific metabolites and to the presence of cytotoxic adjuvants. These features may shift lipid membrane saturation, possibly providing a protective effect to bacteria through an increase in membrane impermeability. This response system in P. ananatis provides a novel model for bacterial herbicide tolerance and adaptation in the environment.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-016-0240-x) contains supplementary material, which is available to authorized users.

Bacillus megaterium strains derived from water and soil exhibit differential responses to the herbicide mesotrione

“…The number of viable cells in the control and herbicide treatment groups is shown in Fig 2 . Generally, the strains behaved differently during treatment with mesotrione or Callisto [ 4 , 5 , 6 ]. For strain CCT 7729, treatment with mesotrione resulted in a large decrease in viable cell numbers by 14 h. In contrast, treatment with Callisto resulted in increased growth by 14 h of incubation.…”

“…Modifications to membrane lipids was determined using the method of Prione et al [ 6 ]. Bacterial cultures were centrifuged at 8,000 × g for 10 min.…”

“…Few studies have evaluated the biodegradation of mesotrione [ 3 , 4 ] and the relationship of this herbicide with the generation of ROS and bacterial damage [ 5 , 6 ]. Mesotrione transformed by Bacillus sp.…”

Redox imbalance caused by pesticides: a review of OPENTOX-related research

“…A toxicity study of sulcotrione (90) showed up-regulation of the genes inducing ROS and antioxidant enzymes in the fava bean cells (Vicia faba), followed by increased lipid peroxidation. Some pathogens, in turn, such as E. coli DH5-α (91) and Pantoea ananatis (92), showed resistance to oxidative stress caused by mesotrione, while human liver cancer Hepg2 cells were only mildly affected by tembotrione (93).…”

Population structure determined by comparative amplicon gene sequencing in biofilm and planktonic bacterial communities from pesticide-contaminated water

“…Notably, contaminated environments expose microbiomes to stressful and selective conditions, and once microorganisms exhibit structural and metabolic adaptations, they can overcome these conditions and survive. These adaptive strategies are linked at the cellular level and to specific populations, allowing different responses to compounds such as pesticides [2,3] and enabling their use in biotechnological processes such as agrochemical degradation [4–6]…”