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BMC Genomics

, 14:430

Comparative and evolutionary genomics


BackgroundMutans streptococci are a group of bacteria significantly contributing to tooth decay. Their genetic variability is however still not well understood.

ResultsGenomes of 6 clinical S. mutans isolates of different origins, one isolate of S. sobrinus DSM 20742 and one isolate of S. ratti DSM 20564 were sequenced and comparatively analyzed. Genome alignment revealed a mosaic-like structure of genome arrangement. Genes related to pathogenicity are found to have high variations among the strains, whereas genes for oxidative stress resistance are well conserved, indicating the importance of this trait in the dental biofilm community. Analysis of genome-scale metabolic networks revealed significant differences in 42 pathways. A striking dissimilarity is the unique presence of two lactate oxidases in S. sobrinus DSM 20742, probably indicating an unusual capability of this strain in producing H2O2 and expanding its ecological niche. In addition, lactate oxidases may form with other enzymes a novel energetic pathway in S. sobrinus DSM 20742 that can remedy its deficiency in citrate utilization pathway.

Using 67 S. mutans genomes currently available including the strains sequenced in this study, we estimates the theoretical core genome size of S. mutans, and performed modeling of S. mutans pan-genome by applying different fitting models. An -open- pan-genome was inferred.

ConclusionsThe comparative genome analyses revealed diversities in the mutans streptococci group, especially with respect to the virulence related genes and metabolic pathways. The results are helpful for better understanding the evolution and adaptive mechanisms of these oral pathogen microorganisms and for combating them.

KeywordsMutans Streptococci Streptococcus Mutans Streptococcus Ratti Streptococcus Sobrinus Comparative Genomics Core-genome Pan-genome Pathogenicity Lactate Oxidase Metabolic Network AbbreviationsPCRPolymerase Chain Reaction

PTSPhosphotransferase system

TCATricarboxylic acid cycle



HGTHorizontal gene transfer

LGTLateral gene transfer

SNPSingle-nucleotide polymorphism

LCBLocally collinear block

multi-MUMsMultiple maximal-unique-matches

COGClusters of orthologous groups of proteins

CSPCompetence stimulating peptide

XIPSigma X-inducing peptide

ABC transporterATP-binding cassette transporter

SODSuperoxide dismutase

NAD+Nicotinamide adenine dinucleotide

NADP+Nicotinamide adenine dinucleotide phosphate


GSSGOxidized glutathione

GCSGlutamylcysteine synthetase

GSGlutathione synthetase

GCS-GSGlutamylcysteine synthetase-glutathione synthetase

CoACoenzyme A.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2164-14-430 contains supplementary material, which is available to authorized users.

An erratum to this article is available at

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Autor: Lifu Song - Wei Wang - Georg Conrads - Anke Rheinberg - Helena Sztajer - Michael Reck - Irene Wagner-Döbler - An-Ping Zen


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