title: Salivaricin E and abundant dextranase activity may contribute to the anti-cariogenic potential of the probiotic candidate Streptococcus salivarius JH.
abstract: Dental caries is an infectious disease that is continuing to increase in prevalence, reducing the quality of life for millions worldwide as well as causing considerable expense, with an estimated US$108 billion spent on dental care in the USA each year. Oral probiotics are now being investigated to determine whether they could play a role in the prevention and treatment of this disease. Streptococcus salivarius strain JH is a potential probiotic candidate that produces multiple proteinaceous antimicrobials (bacteriocins), the inhibitory spectrum of which includes Streptococcus mutans, one of the principal causative agents of dental caries. The genome of strain JH has previously been shown to contain the biosynthetic loci for the bacteriocins salivaricin A3, streptin and streptococcin SA-FF22. Here we show that strain JH also produces salivaricin E, a 32 aa lantibiotic with a mass of 3565.9 Da, which is responsible for the inhibition of S. mutans growth. In addition, strain JH was shown to produce dextranase, an enzyme that hydrolyses (1 → 6)-α-D-glucosidic linkages, at levels higher than any other S. salivarius tested. In vitro testing showed that partial hydrolysis of the exopolymeric substances of S. mutans, using strain JH dextranase, improved the anti-S. mutans inhibitory activity of the lytic bacteriocin, zoocin A. The multiple bacteriocin and dextranase activities of strain JH support its candidature for development as an oral probiotic.
authors.affiliation: Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.
authors.forename: Glenn V
authors.initials: GV
authors.lastname: Walker
authors.affiliation: Sir John Walsh Research Institute (Faculty of Dentistry), University of Otago, Dunedin, New Zealand.
authors.forename: Nicholas C K
authors.initials: NCK
authors.lastname: Heng
authors.affiliation: Department of Biochemistry, University of Otago, Dunedin, New Zealand.
authors.forename: Alan
authors.initials: A
authors.lastname: Carne
authors.affiliation: Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.|Blis Technologies Ltd, Dunedin, New Zealand.
authors.forename: John R
authors.initials: JR
authors.lastname: Tagg
authors.affiliation: Blis Technologies Ltd, Dunedin, New Zealand.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Wescombe
mesh_terms: D001430:Bacteriocins / Q000737:chemistry / Q000378:metabolism*; D003910:Dextranase / Q000378:metabolism*; D008970:Molecular Weight; D019936:Probiotics / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects / Q000254:growth & development; D000070001:Streptococcus salivarius / Q000201:enzymology* / Q000378:metabolism*
chemical_list: D001430:Bacteriocins; D003910:Dextranase