Direct Observation of Bacterial Growth in Giant Unilamellar Vesicles: A Novel Tool for Bacterial Cultures

Bacterial cultivation techniques are classic, basic, and common processes used to characterize the physiological activity of bacteria in their environment. Owing to recent advances in bacterial cultivation techniques, the physiological activity of bacteria can be elucidated at the single-cell culture level. Here, we report a novel method to monitor the real-time activity of bacterial growth at the single-cell level inside giant unilamellar vesicles (GUVs). This method consists of two steps: 1) encapsulation of single bacteria in 1-33 pL scale GUVs and 2) immobilization of the GUVs on a planar lipid bilayer membrane on a glass surface. We directly observed single E. coli cells actively growing to a great number of cells inside GUVs. GUVs also protected the bacteria from external antibiotic compounds during prolonged cultivation for more than 24 h. This approach can be applied widely in the fields of biochemistry, biotechnology, microbiology, and synthetic biology.