Common Mechanistic Action of Bacteriocins from Lactic Acid Bacteria

Abstract

The influence of four bacteriocins from lactic acid bacteria on the proton motive force (PMF) of sensitive organisms was investigated. Pediocin PA-1 (20 pg/ml) and leuconocin S (48.5 jLg/ml) mediated total or major PMF dissipation of energized Listeria monocytogenes Scott A cells in a concentration-dependent manner, as has been shown for nisin. Lactacin F (13.5 ,ug/mi) caused 87% PMF depletion of energized LactobaciUlus delbrueckii ATCC 4797 cells, also in a concentration-dependent fashion. The energy requirements for the activity of these four bacteriocins were determined by using the ionophores nigericin and valinomycin to carry out partial and specific deenergization of the target organisms. Pediocin PA-1, leuconocin S, and lactacin F acted in an energy-independent manner, whereas the activity of nisin was confirmed to be energy dependent. These results together with published reports on other bacteriocins suggest that the bacteriocins of lactic acid bacteria share a common mechanism, the depletion of PMF.

Cell envelope analysis of insensitive, susceptible or resistant strains ofLeuconostocandWeissellagenus toLeuconostoc mesenteroidesFR 52 bacteriocins

“…The similar growth of resistant and parental strains and the rapidly acquired resistance (at least for light resistance) are in accordance with this hypothesis [2,[22][23][24][25]. Nevertheless, two factors should yet be investigated in our model: (i) the membrane protomotive force (PMF) that could influence bacteriocin insertion [10,14,26] and (ii) the existence of a receptor protein, that could permit/limit bacteriocin activity. Analysis of genetically constructed resistants permitted to point out the impact of the r 54 factor, which regulating among others membrane glucosid transporters [27][28][29].…”

Class IIa bacteriocins: biosynthesis, structure and activity

“…A consequence of such disruptions is the dissipation of proton motive force (PMF), which involves the partial or total dissipation of either or both the transmembrane potential (vi) and the pH gradient (vpH) [39]. Unlike lantibiotics, which totally dissipate both vi and vpH [39], class IIa bacteriocins readily provoke a total dissipation of vpH, but only a partial dissipation of vi [17,84,85,88]. Only the newly discovered mundticin has been shown to cause a complete dissipation of vi [21].…”

“…Therefore, altering the charge properties of either the bacteriocin, by changing the medium pH, or the membrane, by changing its lipid composition, obviously in£uences this adhesion by a¡ecting the dissocia- Class IIa bacteriocins are generally opposed to nisin in the sense that they interact with the cytoplasmic membranes of sensitive cells regardless of their degree of prior energization, suggesting that the loss of permeability of the cytoplasmic membrane occurs in a voltage-independent manner [3,49,85,86], while nisin acts in a membrane-potential-dependent manner [5,92]. However, recent investigations have shown, on the one hand, that nisin's dependency on vi varies with the experimental system used: while a threshold level of vi is required for activity in Listeria cells and black lipid membranes, nisin can, however, display activity on lipid vesicles and sensitive lactococcal cells in the absence of vi, though the presence of vi increases its membrane permeabilization ability [5,39,85,92,98]. On the other hand, the antimicrobial activity of the class IIa bacteriocins, pediocin PA-1 and bavaricin MN, has also been shown to be enhanced by vi (66% and 88% increase, respectively), although it is not fully dependent on it [17,31].…”

Effect of Enterocin CRL35 on Listeria monocytogenes cell membrane

“…(IIc) Sec dependent bacteriocins and (IId) class II bacteriocins that do not belong to the other groups. Class IIa bacteriocins, which seem to have a common mechanism of action, would act by dissipating the membrane proton motive gradient [2].…”