We have shown by simulation that surfactant-coated oil (surfactant-precursor) droplets can serve as protocellular containers that are able to divide when coupled to a metabolic turnover of surfactant precursors into surfactants. We have studied both auto-catalytic [4] and catalytic [5] metabolic turnover. In both scenarios, the metabolic reaction changes the surfactant to precursor ratio in the droplets which corresponds to a shift in the surface to volume ratio. The aggregate responds to this change by elongation toward a rod-like aggregate followed by fission when most of the precursor core is digested. The results resemble similar replication mechanisms of micellar aggregates known from experiments [2].
Fig. 1: Replication of the container driven by an autocatalytic metabolism. The turnover of procursors (yellow dimers) into surfactants (green-yellow dimers) drives the elongation of an originally spherical aggregate. After consumption of the precursor core, the elongated aggregate becomes unstable and devides into two spherical aggregates.
In order for this replication cycle to work, amphiphile exchange between aggregate surface and bulk phase must be slow compared to container relaxation after precursor turnover. We have analyzed the stability of the replication mechanism with respect to oil-water repulsion and metabolic turnover rate. No critical values could be identified below which container replication becomes unstable. Instead, the mechanism is generic in the entire parameter range that exhibits micellization [4].