COMMON MECHANISTIC ACTION OF BACTERIOCINS FROM LACTIC-ACID BACTERIA

The influence of four bacteriocins from lactic acid bacteria on the pr oton motive force (PMF) of sensitive organisms was investigated. Pedio cin PA-1 (20 mug/ml) and leuconocin S (48.5 mug/ml) mediated total or major PMF dissipation of energized Listeria monocytogenes Scott A cell s in a concentration-dependent manner, as has been shown for nisin. La ctacin F (13.5 mug/ml) caused 87% PMF depletion of energized Lactobaci llus delbrueckii ATCC 4797 cells, also in a concentration-dependent fa shion. The energy requirements for the activity of these four bacterio cins were determined by using the ionophores nigericin and valinomycin to carry out partial and specific deenergization of the target organi sms. Pediocin PA-1, leuconocin S, and lactacin F acted in an energy-in dependent manner, whereas the activity of nisin was confirmed to be en ergy dependent. These results together with published reports on other bacteriocins suggest that the bacteriocins of lactic acid bacteria sh are a common mechanism, the depletion of PMF.