Highly Variable Streptococcus oralis Strains Are Common among Viridans Streptococci Isolated from Primates
Denapaite, Dalia ; Rieger, Martin ; Köndgen, Sophie ; Brückner, Reinhold ; Ochigava, Irma ; Kappeler, Peter ; Mätz-Rensing, Kerstin ; Leendertz, Fabian et al. Blokesch, Melanie (Eds.)
Zitierfähiger Link (URL): http://resolver.sub.uni-goettingen.de/purl?gs-1/14346
Viridans streptococci were obtained from primates (great apes, rhesus monkeys, and ring-tailed lemurs) held in captivity, as well as from free-living animals (chimpanzees and lemurs) for whom contact with humans is highly restricted. Isolates represented a variety of viridans streptococci, including unknown species. Streptococcus oralis was frequently isolated from samples from great apes. Genotypic methods revealed that most of the strains clustered on separate lineages outside the main cluster of human S. oralis strains. This suggests that S. oralis is part of the commensal flora in higher primates and evolved prior to humans. Many genes described as virulence factors in Streptococcus pneumoniae were present also in other viridans streptococcal genomes. Unlike in S. pneumoniae, clustered regularly interspaced short palindromic repeat (CRISPR)–CRISPR-associated protein (Cas) gene clusters were common among viridans streptococci, and many S. oralis strains were type PI-2 (pilus islet 2) variants. S. oralis displayed a remarkable diversity of genes involved in the biosynthesis of peptidoglycan (penicillin-binding proteins and MurMN) and choline-containing teichoic acid. The small noncoding cia-dependent small RNAs (csRNAs) controlled by the response regulator CiaR might contribute to the genomic diversity, since we observed novel genomic islands between duplicated csRNAs, variably present in some isolates. All S. oralis genomes contained a -Nacetyl- hexosaminidase gene absent in S. pneumoniae, which in contrast frequently harbors the neuraminidases NanB/C, which are absent in S. oralis. The identification of S. oralis-specific genes will help us to understand their adaptation to diverse habitats.