The volume phase transition of chit

The volume phase transition of chitosan capsules is a general property of the changed microenvironment, which is linked to bacterial growth (Supplementary Fig. 3c). For the encapsulated ePop bacteria, the transition is temporally correlated with the circuitmediated lysis, which occurs at a sufficiently high local cell density. The capsule collapse, which is driven by bacterial growth, enhanced export of an encapsulated macromolecule tagged with a fluorescent dye (dextran–rhodamine, molecular weight≈70,000 gmol−1) (Fig. 1d) by ~2.25-fold (M9 medium) as compared to the control, in which the tagged macromolecule was encapsulated with cells that were not able to grow (that is, cells inhibited by an antibiotic). The enhanced export was likely due to the squeezing effect caused by the active shrinking of the capsules (Supplementary Fig. 4a,b). Consistent with this notion, when the macromolecule was encapsulated along with the same bacteria in alginate beads (of similar sizes), which did not respond to cell growth, bacterial growth only led to ~1.5-fold (LB medium) increase in export (Supplementary Fig. 4c) as compared to the basal level (export of the macromolecule with no cell growth), while a ~2.6-fold (LB medium) increase was achieved in the case of chitosan capsules