Despite a considerable interest in prodigiosin, the mechanism of its antibacterial activity is
still poorly understood. In this work, Escherichia coli cells were treated with prodigiosin to
determine its antimicrobial effect on bacterial physiology. The effect of prodigiosin was concentration
dependent. In prodigiosin treated cells above MIC value no significant DNA damage
or cytoplasmic membrane disintegration was observed. The outer membrane,
however, becomes leaky. Cells had severely decreased respiration activity. In prodigiosin
treated cells protein and RNA synthesis were inhibited, cells were elongated but could not
divide. Pre-treatment with prodigiosin improved E. coli survival rate in media containing
ampicillin, kanamycin and erythromycin but not phleomycin. The results suggest that prodigiosin
acts as a bacteriostatic agent in E. coli cells. If prodigiosin was diluted, cells resumed
growth. The results indicate that prodigiosin has distinct mode of antibacterial action in different
bacteria.