Action of divergicin M35, a class IIa bacteriocin, on liposomes and Listeria.
OBJECTIVE
The mode of action of divergicin M35, a class IIa bacteriocin, was studied against Listeria monocytogenes with sensitive (DivS) and resistant (DivM) phenotypes, as well as on synthetic phospholipid liposomes.


RESULTS
Divergicin-induced release of 1,6-diphenyl-1,3,5-hexatriene (DPH) from zwitterionic (DMPC) and anionic (DMPC/DMPG, 4:1) liposomes, divergicin binding to liposomes, intracellular ATP concentration, cation efflux, cell affinity for hydrocarbons and cell lysis were measured and cell damage was visualized by fluorescence imaging and transmission electron microscopy. Divergicin M35 at 5 microg ml(-1) induced DPH efflux from anionic and zwitterionic liposomes at rates of about 2.58% and 1.61% per minute, respectively. DPH efflux rate from anionic liposomes was reduced by about 1.83% and 2.1% per minute in the presence of Li+ and Ca2+, respectively. Binding affinity of divergicin M35 to anionic and zwitterionic liposomes was about 86% and 63%, respectively. Intracellular ATP decreased in the sensitive and the resistant strains by 96.7% and 72.8%, respectively after 20 min of exposure to 5 microg ml(-1) divergicin M35. Lysis of the sensitive strain reached 57% in 18 h at a concentration of 5 microg ml(-1) when compared with the lysis of the divergicin-resistant strain (38.8%). The K+ and Na+ efflux from the divergicin-sensitive strain reached 87% and 80% of the total ion content within 5 min of exposure. This strain also showed higher affinity for hydrocarbons.


CONCLUSIONS
The cell death of listerial strains upon addition of divergicin M35 could result from ATP depletion, K+ and Na+ efflux, and bacteriolysis. This triple biological effect was attenuated in the DivM strain.


CONCLUSIONS
This study contributed to the understanding of the mode of action of divergicin M35, a pediocin-like bacteriocin.
Naghmouchi
K
K
Dairy Research Center STELA, Pavillon Paul Comtois, Université Laval, Québec, QC, Canada. bruno@ciad.mx
Drider
D
D
Fliss
I
I
D000255:Adenosine Triphosphate / Q000032:analysis; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001430:Bacteriocins / Q000494:pharmacology*; D004161:Diphenylhexatriene / Q000378:metabolism; D008081:Liposomes; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008854:Microscopy, Electron / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D010641:Phenotype; D010743:Phospholipids; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D008081:Liposomes; D010743:Phospholipids; C514464:divergicin M35, Carnobacterium divergicin M35; D004161:Diphenylhexatriene; D000255:Adenosine Triphosphate; D012964:Sodium; D011188:Potassium