Testing True Choline Ionic Liquid Biocompatibility from a Biotechnological Standpoint

This work is a first approach to demonstrate the viability of a quantitative biotechnological removal of choline chloride from aqueous effluents. Despite the much vaunted biocompatibility of this ammonium-based ionic liquid, it was demonstrated (both by an ad-hoc F test recommended by the Organization for Economic Co-operation and Development and flask assays) that different microorganisms able to degrade persistent chemicals were not able to metabolize it. Only a halophilic bacterium, recently isolated in our research group ( Halomonas sp.), exhibits the enzymatic mechanism to catalyze the cleavage of the ionic liquid cation. The biotechnological process was optimized by carefully cherry-picking the carbon source and proposing an adaptation strategy. In this way, a complete choline removal was attained in less than 24 h when the surfactant Tween 80 was added to the ionic liquid-containing aqueous effluent.