FIG 3.

Colistin is degraded by B. licheniformis DC-1 during entry into stationary phase. Overnight culture was diluted 1:100 in 3 ml of fresh fermentation medium, and growth was recorded by measuring the OD₆₀₀. Meanwhile, the residual antibacterial activity of colistin at various time points was determined by the cylinder-plate diffusion method. Data are shown as mean values ± standard errors of the means (SEM) from at least three experiments.