Dataset Information

Complete Genome Sequence of Streptococcus salivarius DB-B5, a Novel Probiotic Candidate Isolated from the Supragingival Plaque of a Healthy Female Subject.

ABSTRACT: Streptococcus salivarius DB-B5 was isolated from the supragingival plaque of a healthy female subject. The complete 2.3-Mb genome consists of one circular chromosome, two circular plasmids (including a megaplasmid), and one linear phage-like episome. The genome possesses two separate loci encoding bacteriocins.

SUBMITTER: Fields FR

PROVIDER: S-EPMC7530928 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Complete Genome Sequence of Streptococcus salivarius DB-B5, a Novel Probiotic Candidate Isolated from the Supragingival Plaque of a Healthy Female Subject.

Fields Francisco R FR Li Xuyao X Navarre William W WW Naito Mizue M

Microbiology resource announcements 20201001 40

<i>Streptococcus salivarius</i> DB-B5 was isolated from the supragingival plaque of a healthy female subject. The complete 2.3-Mb genome consists of one circular chromosome, two circular plasmids (including a megaplasmid), and one linear phage-like episome. The genome possesses two separate loci encoding bacteriocins. ...[more]

PMID: 33004456

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Project description:The hydrolysis of urea by urease enzyme of oral bacteria is believed to have a major impact on oral microbial ecology and to be intimately involved in oral health and diseases. To begin to understand the biochemistry and genetics of oral ureolysis, a study of the urease of Streptococcus salivarius, a highly ureolytic organism which is present in large numbers on the soft tissues of the oral cavity, has been initiated. By using as a probe a 0.6-kpb internal fragment of the S. salivarius 57.I ureC gene, two clones from subgenomic libraries of S. salivarius 57.I in an Escherichia coli plasmid vector were identified. Nucleotide sequence analysis revealed the presence of one partial and six complete open reading frames which were most homologous to ureIAB-CEFGD of other ureolytic bacteria. Plasmid clones were generated to construct a complete gene cluster and used to transform E. coli and Streptococcus gordonii DL1, a nonureolytic, dental plaque microorganism. The recombinant organisms expressed high levels of urease activity when the growth medium was supplemented with NiCl2. The urease enzyme was purified from E. coli, and its biochemical properties were compared with those of the urease produced by S. salivarius and those of the urease produced by S. gordonii carrying the plasmid-borne ure genes. In all cases, the enzyme had a Km of 3.5 to 4.1 mM, a pH optimum near 7.0, and a temperature optimum near 60 degrees C. S. gordonii carrying the urease genes was then demonstrated to have a significant capacity to temper glycolytic acidification in vitro in the presence of concentrations of urea commonly found in the oral cavity. The ability to genetically engineer plaque bacteria that can modulate environmental pH through ureolysis will open the way to using recombinant ureolytic organisms to test hypotheses regarding the role of oral ureolysis in dental caries, calculus formation, and periodontal diseases. Such recombinant organisms may eventually prove useful for controlling dental caries by replacement therapy.

Project description:The aim of the study was to evaluate the anti-cariogenic effects of Lactobacillus salivarius by reducing pathogenic species and biofilm mass in a double-species biofilm model. Coexistence of S. mutans with C. albicans can cause dental caries progression or recurrence of the disease in the future. Fifty-nine children with diagnosed early childhood caries (ECC) were recruited onto the study. The condition of the children's dentition was defined according to the World Health Organization guidelines. The participants were divided into children with initial enamel demineralization and children showing dentin damage. The study was performed on the S. mutans and C. albicans clinical strains, isolated from dental plaque of patients with ECC. The effect of a probiotic containing Lactobacillus salivarius on the ability of S. mutans and C. albicans to produce a double-species biofilm was investigated in an in vitro model. The biomass of the formed/non-degraded biofilm was analyzed on the basis of its crystal violet staining. The number of colonies of S. mutans and C. albicans (CFU/mL, colony forming units/mL) forming the biofilm was determined. Microorganism morphology in the biofilm was evaluated using a scanning electron microscope (SEM). In vitro analysis demonstrated that the presence of S. mutans increased the number of C. albicans colonies (CFU/mL); the double-species biofilm mass and hyphal forms produced in it by the yeast. L. salivarius inhibited the cariogenic biofilm formation of C. albicans and S. mutans. Under the influence of the probiotic; the biofilm mass and the number of S. mutans; C. albicans and S. mutans with C. albicans colonies in the biofilm was decreased. Moreover; it can be noted that after the addition of the probiotic; fungi did not form hyphae or germ tubes of pathogenic potential. These results suggest that L. salivarius can secrete intermediates capable of inhibiting the formation of cariogenic S. mutans and C. albicans biofilm; and may inhibit fungal morphological transformation and thereby reduce the pathogenicity of C. albicans; weakening its pathogenic potential. Further research is required to prove or disprove the long-term effects of the preparation and to achieve preventive methods.

Dataset Information

Complete Genome Sequence of Streptococcus salivarius DB-B5, a Novel Probiotic Candidate Isolated from the Supragingival Plaque of a Healthy Female Subject.

Publications

Complete Genome Sequence of Streptococcus salivarius DB-B5, a Novel Probiotic Candidate Isolated from the Supragingival Plaque of a Healthy Female Subject.

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