Efflux of ions and ATP depletion induced by pediocin PA-1 are concomitant with cell death in Listeria monocytogenes Scott A

摘要

The bacteriocin pediocin PA-I (80 AU ml~(-1)), which Is produced by Pediococcus acidilactici PAC 1.0, reduced Listeria monocytpgenes Scott A viability by 4-6 log. Concomitant with the ceil death, pediocin PA-1 induced irreversible K~+ and Pi efflux and ATP depletion in concentration-dependent and time-dependent fashions. The maximum amount of intraceliular K~+ and Pi loss was 520 and 44-6 nmol mg~(-1) CDW, respectively. Intraceilular ATP levels decreased from 2-8 to 0-029 nmol mg~(-1) CDW, corresponding to 98-9% depletion. Less than 0-1% ATP efflux was found with pediocin concentrations up to 200 AU ml~(-1). Approximately 10, 40 and 60 min were required for maximum K~+ efflux, ATP depletion and Pi efflux, respectively. Moreover, pediocin PA-1 depleted 90% of cytoplasmic ATP when only 25% Pi efflux took place. These results suggest that loss of ATP is due to attempts : by the cell to maintain proton-motive force rather than the inability of the cell to produce ATP due to the loss of PL Dithiothreitol-treated PA-1 no longer inhibited the growth of L. monocytogenes cells, and caused neither concentration-dependent ion efflux nor ATP depletion.