KINETICS OF INTERACTION OF COLISTIN WITH LIVE CELLS ESCHERICHIA COLI STUDIED BY BIOLUMINESCENT METHOD
The kinetics dependences of the ATP concentration inside (АТРin) and outside (АТРex) of Е. cоlicells on the colistin concentration and duration of incubation in the LB medium and in saline were obtained using our optimized bioluminescent method. With increasing colistin concentration and duration of cell incubation in the nutrient medium, АТРinrapidly decreased to zero. At the same time, АТРexincreased, reached the limit (20-30% of the initial value of АТРin) and did not changed even after complete cell death. The loss of a signifcant part of АТРinseems to be due to a decrease in the activity of respiratory chain enzymes and ATP synthase functioning in the inner cell membrane, damage of which during incubation with colistin leads to a decrease in the rate and even a stop in ATP synthesis. Comparison of ATPin and ATPex during incubation of cells in the nutrient medium and in saline in the presence of colistin showed that colistin has a stronger bactericidal effect on growing, metabolically active cells, while nongrowing cells deprived of nutrition are more resistant to the action of the antibiotic.