POSTER PRESENTATION ABSTRACTS
Please note: All posters will be displayed in
Salons 10-12.
THURSDAY, 10:15-11:00 AM
Li J, Aroutcheva A, Chikindas ML*.
Mode of action of a novel bacteriocin, lactocin 160 from
vaginal Lactobacillus rhamnosus 160.
Rutgers, The State University of New Jersey tchikindas@aesop.rutgers.edu
*Presenting author
Bacterial vaginosis (BV) is a microecological vaginal
disease resulting from the replacement of healthy vaginal Lactobacillus
by a multi-species pathogenic microflora. Although BV is not life threatening,
it leads to many adverse effects including an increased rate of transmission
and acquisition of HIV, endometriosis, as well as other pelvic inflammatory
diseases and post-surgical infections. In pregnant women, BV is a proven
reason for premature labor and delivery. Endotoxins produced by BV-associated
bacteria can cause serious brain/CNS damage in developing fetuses.
Lactobacillus rhamnosus strain 160 isolated
from a healthy subject's vagina produces an antimicrobial peptide (bacteriocin)
lactocin 160 that kills several vaginal pathogens. The study's objective
was to elucidate the mechanism of antimicrobial action of lactocin 160
using an established model, with Micrococcus luteus ATCC 10420
as a test organism. Sensitivity of M. luteus to lactocin 160
was determined by the diffusion assay. Loss of cellular ATP in the lactocin-treated
cells was elucidated using a commercially-available ATP determination
kit (luciferin-luciferase bioluminescence assay). Dissipation of membrane
potential (Δψ) was studied using fluorophore DiSC3(5) with
the fluorescence spectrum sensitive to changes in Δψ.
Lactocin 160 inhibited growth of M. luteus
ATCC 10420 at a concentration of 5 µg/ml. There were no significant
changes in the intracellular ATP level of M. luteus upon the
addition of 20 µg/ml of lactocin 160. However, the extracellular
ATP level was increased significantly. This means that the treatment
of cells with lactocin 160 resulted in an efflux of ATP from inside
the cells. Therefore, a partially purified lactocin 160 preparation
(16 µg /ml of the bacteriocin in the sample) killed sensitive
cells and dissipated 3.12 ± 0.36% of Δψ.
Lactocin 160 has a mode of action typical for bacteriocins.
It disturbs the cellular membrane (Δψ dissipation) and induces
ATP efflux, most likely due to the pore formation, which is a common
mechanism of action for many bacteriocins.
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