Identification of metabolites produced during the complete biodegradation of 1-butyl-3-methylimidazolium chloride by an enriched activated sludge microbial community

Ionic liquids (ILs) are highly polar solvents with unique physicochemical properties that make them promising green alternatives to volatile organic solvents. Since ILs can be toxic to organisms, the development of methods to degrade ILs into harmless molecules prior to disposal is critical to enhancing their green properties. In this study, metabolites generated during the biodegradation of 1-butyl-3-methylimidazolium chloride (BMIMCl) by an enriched, activated sludge microbial community were investigated. Biodegradation of BMIM and the metabolic products released into the growth media were examined using 1H-NMR spectroscopy and mass spectrometry. To the best of our knowledge, this is the first reported complete primary catabolism of the biodegradation-resistant BMIMCl ionic liquid. The bacterial community responsible for degradation was analyzed using a 16S-rRNA amplicon approach. Although the community was diverse, Bacteroidetes was the predominant phylum. The study provides a greater insight into imidazolium-based IL biodegradability and a means to proactively prevent the ecotoxicity of the BMIM cation and its metabolites, by complete primary biodegradation of the cation and removal of most resulting metabolites, prior to release into aquatic waste streams. [Display omitted] •Enriched microbial consortia can biodegrade recalcitrant ionic liquid pollutants.•Bacteroidetes is the predominant phylum in the microbial community that degrades BMIM.•A combination of mass spectrometry and NMR spectroscopy identified BMIM metabolites.•The major BMIM metabolite is excreted by one microbe and removed by another.