Consumption of MeBr (A) and MeI (B) by MeBr-grown washed cell suspensions incubated with 400 μM MeBr and various concentrations of MeI. Symbols: ●, without MeI; ■, 270 μM MeI; ○, 600 μM MeI; ▴, 1,200 μM MeI; ⧫, 3,000 μM MeI; ◊, sterile medium. The cell density was 3.3 × 108 cells/ml. Symbols represent the mean of three suspensions, and bars indicate ±1 standard deviation. Absence of bars indicates that the error was smaller than the symbols.