Evaluation of Arthrobacter aurescens Strain TC1 as Bioaugmentation Bacterium in Soils Contaminated with the Herbicidal Substance Terbuthylazine.

Vera P. Silva,Tânia Teixeira,Matilde Moreira-Santos,Carla Mateus,Rui Ribeiro,Cristina A. Viegas,Pankaj Kumar Arora

doi:10.1371/journal.pone.0144978

Vera P. Silva, Tânia Teixeira + Show 5 more

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https://doi.org/10.1371/journal.pone.0144978

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Abstract

In the last years the chloro-s-triazine active substance terbuthylazine has been increasingly used as an herbicide and may leave residues in the environment which can be of concern. The present study aimed at developing a bioaugmentation tool based on the soil bacterium Arthrobacter aurescens strain TC1 for the remediation of terbuthylazine contaminated soils and at examining its efficacy for both soil and aquatic compartments. First, the feasibility of growing the bioaugmentation bacterium inocula on simple sole nitrogen sources (ammonium and nitrate) instead of atrazine, while still maintaining its efficiency to biodegrade terbuthylazine was shown. In sequence, the successful and quick (3 days) bioremediation efficacy of ammonium-grown A. aurescens TC1 cells was proven in a natural soil freshly spiked or four-months aged with commercial terbuthylazine at a dose 10× higher than the recommended in corn cultivation, to mimic spill situations. Ecotoxicity assessment of the soil eluates towards a freshwater microalga supported the effectiveness of the bioaugmentation tool. Obtained results highlight the potential to decontaminate soil while minimizing terbuthylazine from reaching aquatic compartments via the soil-water pathway. The usefulness of this bioaugmentation tool to provide rapid environment decontamination is particularly relevant in the event of accidental high herbicide contamination. Its limitations and advantages are discussed.

Highlights

Terbuthylazine (TBA; 2-tert-butylamino-4-chloro-6-ethylamino-1, 3, 5-triazine) is used worldwide to control broad-leaved and grassy weeds in agriculture and forestry situations as well as slime-forming algae, fungi and bacteria in non-agricultural situations [1,2,3]
To further examine whether A. aurescens TC1 cells grown in the different nitrogen sources were effective in the degradation of chlorinated s-triazine herbicides, their ability to remove TBA from a phosphate-salt buffer was examined
We first demonstrated the feasibility of growing A. aurescens TC1 inocula for TBA-contaminated soils bioremediation in three simple sole nitrogen sources instead of ATZ

Summary

Introduction

Terbuthylazine (TBA; 2-tert-butylamino-4-chloro-6-ethylamino-1, 3, 5-triazine) is used worldwide to control broad-leaved and grassy weeds in agriculture and forestry situations as well as slime-forming algae, fungi and bacteria in non-agricultural situations [1,2,3]. This active substance is being increasingly used in the EU since atrazine (ATZ) ban in 2008 [1, 4]. M Moreira-Santos thanks to FCT for a postdoctoral fellowship (reference SFRH/BPD/ 99800/2014), funded by Programa Operacional Potencial Humano of QREN Portugal (2014–2020) and by the Portuguese budget through the Ministry of Education and Science. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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