TITLE:
Primary Mode of Action of Cistus ladaniferus L. Essential Oil Active Fractions on Staphylococcus aureus Strain
AUTHORS:
Elodie Guinoiseau, Anne Luciani, Dominique de Rocca Serra, Yann Quilichini, Liliane Berti, Vannina Lorenzi
KEYWORDS:
Staphylococcus aureus, Cistus ladaniferus Essential Oil, MIC, ATP, Cell Division Blocking, TEM
JOURNAL NAME:
Advances in Microbiology,
Vol.5 No.13,
December
30,
2015
ABSTRACT: The purpose of this study was to investigate the primary mode of action
of Cistus ladaniferus essential oil
active fractions on Staphylococcus aureus strain ATCC6538P (CIP 53.156). The mode of inhibition of the active fractions
was assessed by determining the minimum inhibitory concentration (MIC). The
effects of time on cell integrity were determined by time-kill, bacteriolysis
and loss of 260 and 280-nm-absorbing material assays. Measurement of intra- and
extracellular ATP was used to evaluate the energy remaining in the cells after
treatment. A bacteriostatic and a bactericidal mode of inhibition were
established respectively for acetate and alcohol fractions at their MIC. No
intracellular material leakage and no lysis occurred after treatments with
these fractions. In both cases, we observed a decrease of the ATP level within S. aureus cells whilst there was no proportional
increase outside the cells. However, the effects induced by alcohols are more
pronounced than those provoked by acetates. Indeed, marked structural changes
were observed by transmission electron microscopy (TEM). The septal material of
cells undergoing division became thicker and stained more lightly. The
proportion of septa is also markedly increased and defective with respect to
placement. These observations suggest a blocking in cell division, probably
caused by the inhibition of ATPase or a disturbance in proton motrice force by
the hydrophobic molecules viridiflorol and ledol, mainly present in alcohol
fraction.