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.