Developing a glyphosate-bioremediation strategy using plants and actinobacteria: potential improvement of a riparian environment

GIACCIO, GUSTAVO C.M.; SAEZ, JULIANA M.; ESTÉVEZ, MARÍA C.; SALINAS, BÁRBARA; CORRAL, RAÚL A.; DE GERÓNIMO, EDUARDO; APARICIO, VIRGINIA; ÁLVAREZ, ANALÍA CORRESPONDING AUTHOR

JOURNAL OF HAZARDOUS MATERIALS.

ELSEVIER SCIENCE BV

Año: 2023 vol. 446 p. 130 - 675

0304-3894

The riparian ecosystems are dynamic environments found in the transition zone between terrestrial and aquatic ecosystems and include the riparian vegetation strips (RVS). One of RVS functions’ is the retention of contaminants transported by runoff, such as glyphosate (Gly) and its principal degradation product, the aminomethylphosphonic acid (AMPA). As for all pesticides, microbial degradation is the predominant pathway for Gly dissipation in the soil. In this study, Gly and AMPA were detected in soil samples from a riparian ecosystem in the Austral Pampas, Argentina. Sixty-five actinobacteria strains were isolated from riparian soils, rhizosphere, and plants from RVS (Festuca arundinacea and Salix fragilis); one of them, Streptomyces sp. S5, was selected based on its tolerance to Gly, ability to use it as P and C source, and PGP characteristics. A greenhouse test was carried out, in which plants from RVS, actinobacteria, and their combinations were assessed to bioremediate the riparian soil contaminated with Gly and AMPA. The concentrations of Gly and AMPA were determined in soils and plants to estimate the dissipation of both compounds. All the treatments carried out by plants and/or inoculated actinobacteria dissipate similarly the Gly, reaching between 87% and 92% of Gly dissipation from the soil in 90 days. Conversely, in the case of AMPA, dissipation values between 38% and 42% were obtained by Salix and Festuca treatments, respectively, and they increased to 57% and 70% when the actinobacteria bioinoculant was added to each planted system. Regarding the total dissipation reached by the systems, the higher efficiencies for both Gly and AMPA dissipation were achieved by the non-planted soils bioaugmented with the actinobacterium, with 91% of Gly dissipated and 56% for AMPA. The present study has demonstrated that the treatments performed were effective in bioremediating Gly and AMPA-contaminated soils. According to our study, it could be suggested which strategy could be applied depending on the bioremediation type needed. In the case in situ bioremediation is necessary, the combination of phytoremediation with Festuca or Salix, and the bioaugmentation with the actinobacteria inoculant could be convenient. On the other hand, if ex situ bioremediation is needed, the inoculation of the soil with an actinobacterium highly capable to dissipate Gly and AMPA seems to be the more efficient and easier alternative.