Streptococcus rubneri sp. nov., isolated from the human throat

Abstract

The novel, Gram-stain-positive, ovoid, lactic acid bacterial isolates LMG 27205, LMG 27206, LMG 27207 T and MRI-F 18 were obtained from throat samples of healthy humans. 16S rRNA gene sequence analyses indicated that these isolates belong to the genus Streptococcus, specifically the Streptococcus mitis group, with Streptococcus australis and Streptococcus mitis as the nearest neighbours (99.45 and 98.56 % 16S rRNA gene sequence similarity to the respective type strains). Genotypic fingerprinting by fluorescent amplified fragment length polymorphism (FAFLP) and pulsed-field gel electrophoresis (PFGE), DNA-DNA hybridizations, comparative sequence analysis of pheS, rpoA and atpA and physiological and biochemical tests revealed that these bacteria formed a taxon well separated from its nearest neighbours and other species of the genus Streptococcus with validly published names and, therefore, represent a novel species, for which the name Streptococcus rubneri sp. nov. is proposed, with LMG 27207 T (5DSM 26920 T ) as the type strain.The streptococci are lactic acid bacteria that belong to the phylum Firmicutes, class Bacilli, order Lactobacillales and family Streptococcaceae. Comparative 16S rRNA gene sequence analysis clusters species of the genus Streptococcus into six main species groups (Bentley et al., 1991;Kawamura et al., 1995) that are referred to as the anginosus, bovis, mitis, mutans, pyogenes and salivarius species groups (Kawamura et al., 1995). The mitis group currently includes Streptococcus australis, S. cristatus, S. gordonii, S. infantis, S. lactarius, S. massiliensis, S. mitis, S. oligofermentans, S. oralis, S. parasanguinis, S. peroris, S. pseudopneumoniae, S. pneumoniae, S. sanguinis, S. sinensis and S. tigurinus (Kawamura et al., 1999;Hoshino et al., 2005;Glazunova et al., 2006;Naser, 2006; Martín et al., 2011;Zbinden et al., 2012), and combines the Streptococcus mitis and Streptococcus sanguinis groups reported by Facklam (2002). However, assignment of Streptococcus massiliensis to the mitis group is based on partial sequences of housekeeping genes, and not on a 16S rRNA gene sequence comparison, which allocates it to the mutans group (Glazunova et al., 2006(Glazunova et al., , 2010.Isolates LMG 27205, LMG 27206, LMG 27207 T and MRI-F 18 were obtained during an investigation of the microbial populations associated with the throats of healthy human volunteers taking part in a probiotics study (Seifert et al., 2011). Isolates LMG 27205 and MRI-F 18 were taken from throat swabs of the same individual on different sampling occasions, while LMG 27206 and LMG 27207 T originated from throat swabs of different individuals participating in the study. Streptococci were isolated on Columbia CNA 5 % sheep blood agar (Becton Dickinson) and were purified by repeated streaking using the same medium. Cells were Gram-stained and and observed by microscopy.The nearly complete 16S rRNA gene sequences of all four isolates were determined as follows. DNA was extracted according to the method of Pitcher et al. (19...

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The novel speciesStreptococcus tigurinusand its association with oral infection

“…18 Deeper analyses by different methods such as conventional biochemical testing, molecular analyses and DNA-DNA hybridization techniques proofed the presence of a novel species for which the name S. tigurinus was assigned. group, i.e., Streptococcus dentisani, 21 Streptococcus rubneri 22 and Streptococcus lactarius.…”

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