Cell growth.

Cell growth was performed in a 37°C air bath shaker (220 rpm). A standard cell growth procedure contains three steps, seed culture, preculture, and experimental culture. Cells from a fresh colony in the LB plate were inoculated into LB broth plus 0.3 M NaCl medium (for early adaptation to the high osmolarity) and grown for several hours as seed culture. Seed cultures were then transferred into the medium of the final experimental culture (e.g., high-osmolarity medium) and grown overnight at 37°C as preculture. In the next day, the overnight precultures were inoculated into the same medium as for the preculture at an initial OD₆₀₀ of ∼0.015 as experimental culture. For each condition, we took at least six OD₆₀₀ points (range, 0.05 to 0.5) to obtain an exponential-growth curve for the calculation of growth rate. The OD₆₀₀ was measured using a Thermo Scientific Genesys 30 spectrophotometer.