Anti‐adherence and bactericidal activity of sphingolipids against Streptococcus mutans

Abstract

This study evaluated the anti-biofilm activity of sphingosine, phytosphingosine (PHS), and sphinganine for: (i) anti-adherence activity on hydroxyapatite (HA) surfaces; and (ii) bactericidal activity on different Streptococcus mutans phenotypes (i.e. planktonic cells and cells from a disrupted biofilm). For this, HA discs treated with sphingolipids were incubated with S. mutans and the number of adherent cells was evaluated by both culture and confocal microscopy. Sphinganine strongly inhibited bacterial adherence by 1000-fold compared with an untreated surface. Phytosphingosine and sphingosine inhibited bacterial adherence by eight- and five-fold, respectively, compared with an untreated surface. On saliva-coated HA, sphinganine and PHS inhibited bacterial adherence by 10-fold. Bactericidal activity of sphingolipids was evaluated by culture. For biofilms, the strongest bactericidal activity was exhibited by sphingosine compared with PHS and sphinganine. At a concentration of 12.5 μg ml(-1) , PHS and sphingosine were profoundly effective against planktonic and disrupted biofilms; and sphinganine reduced the number of cells in planktonic form by 100-fold and those derived from a disrupted biofilm by 1000-fold. Atomic force microscopy studies suggested that mechanical stability does not appear to be a factor relevant for anti-fouling activity. The results suggest that sphingolipids may be used to control oral biofilms, especially those loaded with S. mutans.

Phytosphingosine Prevents the Formation of Young Salivary Biofilms in vitro

“…We are aware that the experimental models we used in this study are limited artificial models which only partly represent some aspects of the in vivo situation. In the current study glass surfaces were used instead of hydroxyapatite, in contrast to earlier studies [Cukkemane et al, 2015;Valentijn-Benz et al, 2015;Yonel et al, 2016]. Although this might be considered as a limitation of the study, it did enable the use of real-time imaging in the BioFlux experiments for visual monitoring of the effects of PHS in a dynamic setting.…”

“…This model consists of a custom-made stainless steel lid with 24 clamps that hold the untreated and PHS-treated glass cover slips used as a substratum for the bacterial adhesion. For the anti-adhesive experiments, sterile glass cover slips were treated with PHS in a Tris-Tween buffer as described by Cukkemane et al [2015]. As control, glass cover slides were treated with Tris-Tween buffer only.…”

“…In parallel to antimicrobial peptides [Rautenbach et al, 2016], the PHS structure appears ideal for insertion into the cellular membrane of microorganisms; its aliphatic chains are aligned with the fatty acid chains of the phospholipid bilayer, and at the same time their positively charged head groups are electrostatically interacting with the negatively charged phospholipid head groups. This insertion leads to membrane disruption and disturbance of the intracellular molecular machinery [Bergsson et al, 2001a, b;Fischer et al, 2012Fischer et al, , 2013Cukkemane et al, 2015]. Under static conditions, it was recently found that the presence of a PHS coating inhibited the adherence of Streptococcus mutans on bare and salivacoated surfaces by 90% [Cukkemane et al, 2015].…”

“…This insertion leads to membrane disruption and disturbance of the intracellular molecular machinery [Bergsson et al, 2001a, b;Fischer et al, 2012Fischer et al, , 2013Cukkemane et al, 2015]. Under static conditions, it was recently found that the presence of a PHS coating inhibited the adherence of Streptococcus mutans on bare and salivacoated surfaces by 90% [Cukkemane et al, 2015]. Inspired by these findings, the anti-adhesive and anti-biofilm properties of PHS were further explored in both static and dynamic in vitro biofilm models against a broad microbial inoculum: a salivary inoculum.…”

Di-Calcium Phosphate and Phytosphingosine as an Innovative Acid-Resistant Treatment to Occlude Dentine Tubules

“…Moreover, it has been recently reported that the pre-treatment of experimental hydroxyapatite (HAp) discs with sphingoid bases such as sphingosine, phytosphingosine (PHS), PHS phosphate and sphinganine significantly protected HAp against acid demineralisation in vitro [Valentijn-Benz et al, 2015] . Cukkemane et al [2015], using atomic force microscopy, reported that PHS and other sphingoid bases have the ability to form diffusion barriers against H + ions and bacteria. In principle, the reported anti-erosive properties would suggest that PHS could be included in oral care products for the management and treatment of DH.…”