Enhancing osmotic stress tolerance of cell mimetics by modulating lipid bilayer.

Seeking effective ways to maintain cellular homeostasis is crucial to the survival of organisms when they encounter osmotic stress. Glycine betaine (GB) is a widely generated natural osmolyte, but its endogenous production and action are limited. Herein, a kind of nonionic surfactant dodecyl-β-d-glucopyranoside (DG) and a common polymer polyethylene glycol (PEG) are proven to have the ability to enhance the osmotic stress (induced by sugar concentration changes) tolerance of cell and organism models, those are giant unilamellar vesicles (GUVs) and gram-negative Escherichia coli. DG or PEG only induces small size decrease and certain shape change of GUVs. Importantly, DG or PEG at the concentration 100 times lower than that of GB effectively increases the survival rate of bacteria under both hypoosmotic and hyperosmotic conditions. This intriguing result is attributed to the insertion of DG or adsorption of PEG in the lipid bilayer membrane, leading to enhanced membrane permeability. These exogenous substances can replace GB to facilely and highly efficiently augment adaptation of organisms to osmotic stress.