Streptococcus wuxiensis sp. nov., Streptococcus jiangnanensis sp. nov. and Streptococcus fermentans sp. nov.: three novel species of genus Streptococcus isolated from human breast milk
Three novel coccoid-shaped strains, designated 21WXBC0057M1<sup>T</sup>, 21WXBC0044M1<sup>T</sup> and BJSWXB5TM5<sup>T</sup>, were isolated from human breast milk in Wuxi, Jiangsu Province, China. These strains were facultative anaerobes, catalase-negative and Gram-positive. Through a comprehensive analysis of rRNA genes, protein-coding housekeeping genes and genomic phylogeny, we identified these strains as belonging to the genus <i>Streptococcus</i>. Specifically, strain 21WXBC0057M1<sup>T</sup> was phylogenetically most closely related to <i>Streptococcus infantis,</i> strain 21WXBC0044M1<sup>T</sup> was most closely related to <i>Streptococcus oralis</i> and strain BJSWXB5TM5<sup>T</sup> displayed similarities to <i>Streptococcus australis, Streptococcus peroris</i> and <i>S. infantis</i>. The pairwise average nucleotide identity and digital DNA-DNA hybridization values for these three strains were below 95 and 70%, respectively, indicating that they occupied evolutionary branches distinct from all previously validly published <i>Streptococcus</i> species. Distinctive phenotypic characteristics discriminated these novel species from the type strains of their most closely related species. The major cellular fatty acids in the three strains were C<sub>16 : 0</sub> and C<sub>18 : 0</sub>. Genome annotation and a thorough examination of carbohydrate-active enzyme distribution highlighted the observation that all strains possessed extensive capabilities for carbohydrate metabolism, particularly human milk oligosaccharides utilization. Thus, based on these findings, we proposed the classification of the strains as representing three novel species within the genus <i>Streptococcus: Streptococcus wuxiensis</i> sp. nov. (type strain 21WXBC0057M1<sup>T</sup>=GDMCC 1.4126<sup>T</sup>=KCTC 25760<sup>T</sup>), <i>Streptococcus jiangnanensis</i> sp. nov. (type strain 21WXBC0044M1<sup>T</sup>= GDMCC 1.4127<sup>T</sup>=KCTC 25762<sup>T</sup>) and <i>Streptococcus fermentans</i> sp. nov. (type strain BJSWXB5TM5<sup>T</sup>=GDMCC 1.4130<sup>T</sup>=KCTC 25759<sup>T</sup>).
Authors
- Bo Yang (ORCID: https://orcid.org/0000-0002-1347-3718)
- R. Paul Ross (ORCID: https://orcid.org/0000-0003-4876-8839)
- Catherine Stanton (ORCID: https://orcid.org/0000-0003-0405-0665)
- Wei Chen (ORCID: https://orcid.org/0000-0003-3348-4710)
- Jianxin Zhao (ORCID: https://orcid.org/0000-0003-4516-0799)
- Ye Zhou
Institutions
- Jiangnan University (CN)
- Teagasc - The Irish Agriculture and Food Development Authority (IE)
- University College Cork (IE)
- APC Microbiome Institute (IE)
- State Key Laboratory of Food Science and Technology (CN)
Publication Details
- Journal
- INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY
- Published
- 2025-02-07
- DOI
- https://doi.org/10.1099/ijsem.0.006674
- Primary Topic
- Genomics and Phylogenetic Studies
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Key Research and Development Program of China
- Fundamental Research Funds for the Central Universities
- Collaborative Innovationcenter of Food Safety and Quality Control in Jiangsu Province