title: Phylogenomic and MALDI-TOF MS analysis of Streptococcus sinensis HKU4T reveals a distinct phylogenetic clade in the genus Streptococcus.
abstract: Streptococcus sinensis is a recently discovered human pathogen isolated from blood cultures of patients with infective endocarditis. Its phylogenetic position, as well as those of its closely related species, remains inconclusive when single genes were used for phylogenetic analysis. For example, S. sinensis branched out from members of the anginosus, mitis, and sanguinis groups in the 16S ribosomal RNA gene phylogenetic tree, but it was clustered with members of the anginosus and sanguinis groups when groEL gene sequences used for analysis. In this study, we sequenced the draft genome of S. sinensis and used a polyphasic approach, including concatenated genes, whole genomes, and matrix-assisted laser desorption ionization-time of flight mass spectrometry to analyze the phylogeny of S. sinensis. The size of the S. sinensis draft genome is 2.06 Mb, with GC content of 42.2%. Phylogenetic analysis using 50 concatenated genes or whole genomes revealed that S. sinensis formed a distinct cluster with Streptococcus oligofermentans and Streptococcus cristatus, and these three streptococci were clustered with the "sanguinis group." As for phylogenetic analysis using hierarchical cluster analysis of the mass spectra of streptococci, S. sinensis also formed a distinct cluster with S. oligofermentans and S. cristatus, but these three streptococci were clustered with the "mitis group." On the basis of the findings, we propose a novel group, named "sinensis group," to include S. sinensis, S. oligofermentans, and S. cristatus, in the Streptococcus genus. Our study also illustrates the power of phylogenomic analyses for resolving ambiguities in bacterial taxonomy.
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China skplau@hku.hk pcywoo@hku.hk.
authors.forename: Jade L L
authors.initials: JL
authors.lastname: Teng
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China Department of Microbiology, The University of Hong Kong, Hong Kong, China skplau@hku.hk pcywoo@hku.hk.
authors.forename: Yi
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China.
authors.forename: Herman
authors.initials: H
authors.lastname: Tse
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China.
authors.forename: Jonathan H K
authors.initials: JH
authors.lastname: Chen
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China skplau@hku.hk pcywoo@hku.hk.
authors.forename: Susanna K P
authors.initials: SK
authors.lastname: Lau
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong, China Research Centre of Infection and Immunology, The University of Hong Kong, Hong Kong, China State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China skplau@hku.hk pcywoo@hku.hk.
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
mesh_terms: D001482:Base Composition / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D010802:Phylogeny; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013291:Streptococcus / Q000145:classification* / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial
keywords: Illumina; Streptococcus sinensis; genome; phylogenomic; “sinensis group”