Lecithin-based water-in-oil compartments as dividing bioreactors.

Like liposomes, water-in-oil (w/o) emulsions have recently been used as bioreactors, since they permit facile compartmentation, and therefore the creation of a synthetic cell-like structure. We show here for the first time that lecithin-based w/o compartments can also be used for these purposes and in particular as compartments for hosting complex biochemical reactions that lead to protein synthesis. The expression of enhanced green fluorescent protein (EGFP), used as a model reaction, was followed by fluorescence microscopy. EGFP was synthesised inside the bioreactors either through simultaneous incorporation of all components for transcription and translation reactions in a single emulsion, or through the mixing of four different emulsions, each containing only part of the molecular machinery. Mechanical energy (i.e., stirring) must be provided to the system in order to force solute exchange and/or fusion processes between droplets. Finally, we demonstrate that, in the presence of excess lecithin, preformed w/o compartments can undergo spontaneous division, reducing the average droplet size, increasing the number of droplets, and continuing the protein expression after the division. We briefly comment on how this type of work extends and links the previously reported work on self-reproduction in vesicles, micelles and reverse-micelles.