Glyphosate versus glyphosate based ionic liquids: Effect of cation on glyphosate biodegradation, soxA and phnJ genes abundance and microbial populations changes during soil bioaugmentation

• Published in: Chemosphere (Oxford) 2023-03, Vol.316, p.137717, Article 137717
• Main Authors: Wilms, Wiktoria, Parus, Anna, Homa, Jan, Batycka, Milena, Niemczak, Michał, Woźniak-Karczewska, Marta, Trzebny, Artur, Zembrzuska, Dabert, Mirosława, Táncsics, András, Cajthaml, Tomas, Heipieper, Hermann J., Chrzanowski, Łukasz
• Format: Article
• Language: English
• Subjects: Anions - chemistry; Bioaugmentation; Bioavailabilty; Cations - chemistry; Degradation; Glyphosate; Herbicidal ionic liquids (HILs); Herbicides - chemistry; Herbicides - toxicity; Ionic Liquids - chemistry; Ionic Liquids - toxicity; Microbial toxicity; Quaternary ammonium cations (QAC); Soil Microbiology
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.137717

The applicability of herbicidal ionic liquids (HILs) as an alternative form of herbicides is currently evaluated. Yet, the available research is lacking information on the behaviour of herbicidal ionic liquids upon addition to the environment, i.e., if cations and anions act as separate moieties or remain an ionic salt. Hence, we tested degradation of five HILs with the glyphosate anion, their bioavailability in soil, toxicity towards microorganisms, impact on the biodiversity and the abundance of phnJ and soxA genes. The cations were proven to be slightly or moderately toxic. The properties of cations determined the properties of the whole formulation, which might suggest that cations and anion act as the independent mixture of ions. The mineralisation efficiencies were in the range of 15–53%; however, in the case of cations (except non-toxic choline), only 13–20% were bioavailable for degradation. The hydrophobic cations were proven to be highly sorbed, while the anion was readily available for microbial degradation regardless of its counterion. The approach to enrich test samples with isolated microorganisms specialised in glyphosate degradation resulted in higher degradation efficiencies, yet not high enough to mitigate the negative impact of cations. In addition, increased activity of enzymes participating in glyphosate degradation was observed. In the view of obtained results, the use of cationic surfactants in HILs structure is not recommended, as sorption was shown to be determining factor in HILs degradation efficiency. Moreover, obtained results indicate that corresponding ions in HILs might act as separate moieties in the environment. [Display omitted] •Cations and anions in HILs act as separate moieties in soils.•Quaternary ammonium cations in HILs are toxic and tend to sorb in soils.•Bioaugmentation approach was insufficient to minimise cation's impact.•Toxicity and biodegradation of HILs are reflecting cation's properties.