title: Sustainable inhibition efficacy of liposome-encapsulated nisin on insoluble glucan-biofilm synthesis by Streptococcus mutans.
abstract: BACKGROUND
  Dental caries are an infectious oral bacterial disease caused by cariogenic streptococci. These streptococci inhabit dental biofilms which comprise insoluble glucans.
  
  
  OBJECTIVE
  To prevent dental caries, nisin, a suitable agent active against Gram-positive bacteria, was examined in vitro for its ability to suppress insoluble glucan-biofilm synthesis by cariogenic streptococci.
  
  
  METHODS
  To investigate glucan-biofilm synthesis by a typical cariogenic streptococcus, Streptococcus mutans 10449, the naked form of nisin was loaded onto a 96-well microplate in vitro model. To prolong the efficacy of nisin as a preventive agent, liposome-encapsulated nisin (nisin-liposome) was examined for its ability to inhibit the synthesis of glucan-biofilms on microplates.
  
  
  RESULTS
  Naked nisin (100 pmol) completely suppressed insoluble glucan-biofilm synthesis by S. mutans 10449 following 1 h cultivation in 96-well microplates. The concentration of nisin-liposome required for the efficacious inhibition of glucan-biofilm synthesis was four times lower than that of naked nisin following 2 h cultivation. In particular, nisin-liposome (30 pmol nisin equivalent) prolonged the inhibitory activity of nisin against glucan-biofilm synthesis by S. mutans 10449 for up to 6 h, while naked nisin (30 pmol) gradually lost this inhibitory activity over the same period. In vitro release assay of nisin from the liposome showed that 76% nisin was released within 6 h.
  
  
  CONCLUSIONS
  The findings indicate the usefulness of nisin-liposome for the sustained release of nisin. Thus, nisin-liposome could play a potential role in preventive medicine as an inhibitor of the glucan-biofilm synthesis.
authors.affiliation: Department of Preventive Medicine and Public Health, National Defense Medical College, Namiki, Tokorozawa, Japan. yamakami@ndmc.ac.jp
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamakami
authors.forename: Hideaki
authors.initials: H
authors.lastname: Tsumori
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Sakurai
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Kohei
authors.initials: K
authors.lastname: Nagatoshi
authors.forename: Kenji
authors.initials: K
authors.lastname: Sonomoto
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D018441:Biofilms / Q000145:classification* / Q000254:growth & development; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D003731:Dental Caries / Q000382:microbiology / Q000517:prevention & control*; D005936:Glucans / Q000096:biosynthesis*; D007700:Kinetics; D008081:Liposomes; D009561:Nisin / Q000737:chemistry / Q000494:pharmacology*; D012995:Solubility; D013295:Streptococcus mutans / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D003692:Delayed-Action Preparations; D005936:Glucans; D008081:Liposomes; D009561:Nisin