Biodegradation of pyridinium-based ionic liquids by an axenic culture of soil Corynebacteria

We investigated the biodegradation of ionic liquids N-ethylpyridinium tetrafluoroborate [EtPy]⁺[BF₄]⁻, N-ethylpyridinium trifluoroacetate [EtPy]⁺[CF₃COO]⁻, and 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM]⁺[PF₆]⁻ by a soil bacterium isolated by an enrichment-culture technique. The bacterium identified as Corynebacterium sp. degraded the N-ethylpyridinium cation in the first two compounds when present as its sole carbon and nitrogen source without any obvious effects of the anion; however, [BMIM]⁺[PF₆]⁻ was not metabolized. We observed cleavage of the pyridinium ring and identified the resulting metabolites by ESI/MS/MS. We propose a degradation pathway.