Toggle Main Menu Toggle Search

Open Access padlockePrints

Generation of diversity in Streptococcus mutans genes demonstrated by MLST

Lookup NU author(s): Emeritus Professor Roy Russell



Streptococcus mutans, consisting of serotypes c, e, f and k, is an oral aciduric organism associated with the initiation and progression of dental caries. A total of 135 independent Streptococcus mutans strains from caries-free and caries-active subjects isolated from various geographical locations were examined in two versions of an MLST scheme consisting of either 6 housekeeping genes [accC (acetyl-CoA carboxylase biotin carboxylase subunit), gki (glucokinase), lepA (GTP-binding protein), recP (transketolase), sodA (superoxide dismutase), and tyrS (tyrosyl-tRNA synthetase)] or the housekeeping genes supplemented with 2 extracellular putative virulence genes [gtfB (glucosyltransferase B) and spaP (surface protein antigen I/II)] to increase sequence type diversity. The number of alleles found varied between 20 (lepA) and 37 (spaP). Overall, 121 sequence types (STs) were defined using the housekeeping genes alone and 122 with all genes. However p, nucleotide diversity per site, was low for all loci being in the range 0.019-0.007. The virulence genes exhibited the greatest nucleotide diversity and the recombination/mutation ratio was 0.67 [95% confidence interval 0.3-1.15] compared to 8.3 [95% confidence interval 5.0-14.5] for the 6 concatenated housekeeping genes alone. The ML trees generated for individual MLST loci were significantly incongruent and not significantly different from random trees. Analysis using ClonalFrame indicated that the majority of isolates were singletons and no evidence for a clonal structure or evidence to support serotype c strains as the ancestral S. mutans strain was apparent. There was also no evidence of a geographical distribution of individual isolates or that particular isolate clusters were associated with caries. The overall low sequence diversity suggests that S. mutans is a newly emerged species which has not accumulated large numbers of mutations but those that have occurred have been shuffled as a consequence of intra-species recombination generating genotypes which can be readily distinguished by sequence analysis. © 2010 Do et al.

Publication metadata

Author(s): Do T, Gilbert S, Clark D, Ali F, Fatturi Parolo C, Maltz M, Russell R, Holbrook P, Wade W, Beighton D

Publication type: Article

Publication status: Published

Journal: PLoS ONE

Year: 2010

Volume: 5

Issue: 2

Print publication date: 05/02/2010

Date deposited: 11/05/2011

ISSN (electronic): 1932-6203

Publisher: Public Library of Science


DOI: 10.1371/journal.pone.0009073

PubMed id: 20140210


Altmetrics provided by Altmetric