Mode of action and safety of lactosporin, a novel antimicrobial protein produced by Bacillus coagulans  ATCC 7050.
OBJECTIVE
To determine the mechanism of action of antimicrobial protein, lactosporin, against Gardnerella vaginalis and to evaluate its safety in vitro.


RESULTS
Bacillus coagulans ATCC 7050 was grown at 37°C for 18 h. The cell-free supernatant was concentrated 10-fold and screened for antimicrobial activity against indicator strain Micrococcus luteus. The mode of action of lactosporin was determined by measuring the potassium release and monitoring the changes in transmembrane potential (Δψ) and transmembrane pH (ΔpH) of the sensitive cells. Lactosporin caused the efflux of potassium ions from M. luteus cells and dissipation of ΔpH in G. vaginalis, while it had no effect on the Δψ. The safety of lactosporin was evaluated by using EpiVaginal(™) ectocervical (VEC-100) tissue model. Over 80% of the cells in the vaginal tissue remained viable after exposure to lactosporin for 24 h.


CONCLUSIONS
Lactosporin potentially exerts its antimicrobial activity by selective dissipation of ΔpH and/or by causing leakage of ions from the sensitive cells. Safety studies suggest that lactosporin is a noncytotoxic antimicrobial for vaginal application.


CONCLUSIONS
This study revealed that lactosporin is an effective and safe antimicrobial preparation with potential application for the control of bacterial vaginosis.
School of Environmental and Biological Sciences, Rutgers State University, New Brunswick, NJ, USA.
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Riazi
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Dover
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Chikindas
D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001407:Bacillus / Q000378:metabolism*; D001430:Bacteriocins / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D006194:Gardnerella vaginalis / Q000187:drug effects* / Q000254:growth & development; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials / Q000187:drug effects; D016982:Micrococcus luteus / Q000187:drug effects; D011188:Potassium / Q000032:analysis; D018892:Proton-Motive Force; D014621:Vagina / Q000166:cytology / Q000187:drug effects / Q000382:microbiology; D016585:Vaginosis, Bacterial / Q000188:drug therapy
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D011188:Potassium