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

Abstract

The intense use of herbicides for weed control in agriculture causes selection pressure on soil microbiota and water ecosystems, possibly resulting in changes to microbial processes, such as biogeochemical cycles. These xenobiotics may increase the production of reactive oxygen species and consequently affect the survival of microorganisms, which need to develop strategies to adapt to these conditions and maintain their ecological functionality. This study analyzed the adaptive responses of bacterial isolates belonging to the same species, originating from two different environments (water and soil), and subjected to selection pressure by herbicides. The effects of herbicide Callisto and its active ingredient, mesotrione, induced different adaptation strategies on the cellular, enzymatic, and structural systems of two Bacillus megaterium isolates obtained from these environments. The lipid saturation patterns observed may have affected membrane permeability in response to this herbicide. Moreover, this may have led to different levels of responses involving superoxide dismutase and catalase activities, and enzyme polymorphisms. Due to these response systems, the strain isolated from water exhibited higher growth rates than did the soil strain, in evaluations made in oligotrophic culture media, which would be more like that found in semi-pristine aquatic environments. The influence of the intracellular oxidizing environments, which changed the mode of degradation of mesotrione in our experimental model and produced different metabolites, can also be observed in soil and water at sites related to agriculture. Since the different metabolites may present different levels of toxicity, we suggest that this fact should be considered in studies on the fate of agrochemicals in different environments.

Plant Growth and Drought Tolerance-Promoting Bacterium for Bioremediation of Paraquat Pesticide Residues in Agriculture Soils

“…The genus Bacillus is well known for its xenobiotic degradation and plant growth promotion abilities. For example, B. megaterium strains CCT 7729 and CCT 7730 were found to degrade 49.7 and 62.5% of mesotrione in 14 h ( Dobrzanski et al, 2018 ), B. thuringiensis strain SG4 was found to degrade 85.0% of cypermethrin in 15 days ( Pankaj et al, 2020 ) and 90% of chlorpyrifos 3,5,6-trichloro-2-pyridinol in 8 days ( Samina et al, 2009 ). Our study supports the reports from those previous studies.…”

Herbicide bioremediation: from strains to bacterial communities

“…Structural changes are also related to herbicide-induced stress tolerance. Changes in the membrane lipid saturation pattern in bacteria can act as selective barriers against herbicides ( Dobrzanski et al., 2018 ; Prione et al., 2016 ; Rodríguez-Castro et al., 2019 ). In this review, we use the term “resistance” to refer to the ability of bacteria to grow in the presence of herbicides, irrespective of duration of treatment ( Brauner et al., 2016 ).…”

“…While some bacterial responses to herbicides are specific, such as induction and modulation of antioxidant enzymes and herbicide degradation genes, others generate nonspecific responses that lessen secondary damage to cellular functions. For example, the herbicide Callisto was shown to induce changes in lipid saturation and membrane permeability in Bacillus megaterium strains isolated from various agricultural environments ( Dobrzanski et al., 2018 ). Complementary routes to obtain energy can also be used to reduce the toxicity of herbicides.…”

Structuring biofilm communities living in pesticide contaminated water

“…Notably, contaminated environments expose microbiota to stressful and selective conditions, and microorganisms can then undergo structural and metabolic adaptations to survive under these conditions (Olson et al, 2017). These adaptive strategies are linked at the cellular level to specific microbial populations, which results in different responses to compounds such as pesticides (Prione et al, 2016;Dobrzanski et al, 2018) and allows their use in biotechnological processes to help degrade them in the environment (Martins et al, 2007;Silva et al, 2007;Olchanheski et al, 2014).…”