Characterization of Streptococcus mitis subsp. carlssonii isolated from human vagina: prevalence, phenotypic, and genomic insights

The genus Streptococcus is a heterogenous group of commensal and pathogenic bacteria. Members of this genus are classified into two major groups, the pyogenic group and the viridans group streptococci (VGS). VGS are frequently found as normal members of the human microbiome and are regarded as comme...

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Main Authors: Jake Adolf V. Montecillo, Jung Hwa Lee, Heon Jong Yoo, Yoo-Young Lee, Chul Min Park, Angela Cho, Hyunsu Lee, Jong Mi Kim, Nan Young Lee, Sun-Hyun Park, Nora Jee-Young Park, Hyung Soo Han, Gun Oh Chong, Incheol Seo
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-08-01
Series:Frontiers in Microbiology
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Online Access:https://www.frontiersin.org/articles/10.3389/fmicb.2025.1625724/full
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author Jake Adolf V. Montecillo
Jake Adolf V. Montecillo
Jake Adolf V. Montecillo
Jung Hwa Lee
Jung Hwa Lee
Heon Jong Yoo
Yoo-Young Lee
Chul Min Park
Angela Cho
Hyunsu Lee
Jong Mi Kim
Jong Mi Kim
Nan Young Lee
Sun-Hyun Park
Nora Jee-Young Park
Nora Jee-Young Park
Hyung Soo Han
Hyung Soo Han
Hyung Soo Han
Gun Oh Chong
Gun Oh Chong
Incheol Seo
Incheol Seo
Incheol Seo
author_facet Jake Adolf V. Montecillo
Jake Adolf V. Montecillo
Jake Adolf V. Montecillo
Jung Hwa Lee
Jung Hwa Lee
Heon Jong Yoo
Yoo-Young Lee
Chul Min Park
Angela Cho
Hyunsu Lee
Jong Mi Kim
Jong Mi Kim
Nan Young Lee
Sun-Hyun Park
Nora Jee-Young Park
Nora Jee-Young Park
Hyung Soo Han
Hyung Soo Han
Hyung Soo Han
Gun Oh Chong
Gun Oh Chong
Incheol Seo
Incheol Seo
Incheol Seo
author_sort Jake Adolf V. Montecillo
collection DOAJ
description The genus Streptococcus is a heterogenous group of commensal and pathogenic bacteria. Members of this genus are classified into two major groups, the pyogenic group and the viridans group streptococci (VGS). VGS are frequently found as normal members of the human microbiome and are regarded as commensals. In this work, we characterized a VGS strain isolated from the vaginal swab sample of a Korean patient diagnosed with endometrial cancer. Phylogenetic, phenotypic, and genome-based analyses confirmed the classification of the strain K0074 as a member of the S. mitis complex. Based on the phylogenetic analyses, the species belonged to the recently established Streptococcus mitis subsp. carlssonii. The strain was found to be rare in the vaginal microbiome, but prevalent in the oral and nasal microbiome samples. K0074 neither triggered an inflammatory response nor caused cytolytic and cytotoxic effects on human cervical cancer cell line. Genome analysis uncovered the genetic basis of the strain's metabolism, virulence factors, and potential antimicrobial resistance phenotypes. Moreover, comparative genomics of the strain and closely related species and subspecies highlighted their striking differences in gene properties and biological functions. Overall, the new strain exhibited low virulence and pathogenic potentials and thus, is regarded as a commensal member of the human microflora. The genetic divergence of K0074 from closely related strains offers a compelling foundation for future investigations into the strain's potential functional specialization and its adaptation within the vaginal microbiome.
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spelling doaj-art-71d5d28f945a4fa8bf7dddb2dc3dacb82025-08-25T10:12:17ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2025-08-011610.3389/fmicb.2025.16257241625724Characterization of Streptococcus mitis subsp. carlssonii isolated from human vagina: prevalence, phenotypic, and genomic insightsJake Adolf V. Montecillo0Jake Adolf V. Montecillo1Jake Adolf V. Montecillo2Jung Hwa Lee3Jung Hwa Lee4Heon Jong Yoo5Yoo-Young Lee6Chul Min Park7Angela Cho8Hyunsu Lee9Jong Mi Kim10Jong Mi Kim11Nan Young Lee12Sun-Hyun Park13Nora Jee-Young Park14Nora Jee-Young Park15Hyung Soo Han16Hyung Soo Han17Hyung Soo Han18Gun Oh Chong19Gun Oh Chong20Incheol Seo21Incheol Seo22Incheol Seo23Department of Immunology, School of Medicine, Kyungpook National University, Daegu, Republic of KoreaClinical Omics Institute, Kyungpook National University, Daegu, Republic of KoreaBrain Korea 21 FOUR Program, School of Medicine, Kyungpook National University, Daegu, Republic of KoreaDepartment of Immunology, School of Medicine, Kyungpook National University, Daegu, Republic of KoreaClinical Omics Institute, Kyungpook National University, Daegu, Republic of KoreaChungnam National University School of Medicine, Daejeon, Republic of KoreaGynecologic Cancer Center, Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of KoreaDepartment of Obstetrics and Gynecology, Jeju National University Hospital, Jeju National University College of Medicine, Jeju, Republic of KoreaDepartment of Obstetrics and Gynecology, Jeju National University Hospital, Jeju National University College of Medicine, Jeju, Republic of KoreaDepartment of Physiology, Pusan National University School of Medicine, Yangsan, Republic of KoreaClinical Omics Institute, Kyungpook National University, Daegu, Republic of KoreaDepartment of Obstetrics and Gynecology, Kyungpook National University Chilgok Hospital, Daegu, Republic of KoreaDepartment of Clinical Pathology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea0Division of Advanced Predictive Research, Center for Bio-Signal Research, Korea Institute of Toxicology (KIT), Daejeon, Republic of KoreaClinical Omics Institute, Kyungpook National University, Daegu, Republic of Korea1Department of Pathology, Kyungpook National University Chilgok Hospital, Daegu, Republic of KoreaClinical Omics Institute, Kyungpook National University, Daegu, Republic of KoreaBrain Korea 21 FOUR Program, School of Medicine, Kyungpook National University, Daegu, Republic of Korea2Department of Physiology, School of Medicine, Kyungpook National University, Daegu, Republic of KoreaClinical Omics Institute, Kyungpook National University, Daegu, Republic of KoreaDepartment of Obstetrics and Gynecology, Kyungpook National University Chilgok Hospital, Daegu, Republic of KoreaDepartment of Immunology, School of Medicine, Kyungpook National University, Daegu, Republic of KoreaClinical Omics Institute, Kyungpook National University, Daegu, Republic of KoreaBrain Korea 21 FOUR Program, School of Medicine, Kyungpook National University, Daegu, Republic of KoreaThe genus Streptococcus is a heterogenous group of commensal and pathogenic bacteria. Members of this genus are classified into two major groups, the pyogenic group and the viridans group streptococci (VGS). VGS are frequently found as normal members of the human microbiome and are regarded as commensals. In this work, we characterized a VGS strain isolated from the vaginal swab sample of a Korean patient diagnosed with endometrial cancer. Phylogenetic, phenotypic, and genome-based analyses confirmed the classification of the strain K0074 as a member of the S. mitis complex. Based on the phylogenetic analyses, the species belonged to the recently established Streptococcus mitis subsp. carlssonii. The strain was found to be rare in the vaginal microbiome, but prevalent in the oral and nasal microbiome samples. K0074 neither triggered an inflammatory response nor caused cytolytic and cytotoxic effects on human cervical cancer cell line. Genome analysis uncovered the genetic basis of the strain's metabolism, virulence factors, and potential antimicrobial resistance phenotypes. Moreover, comparative genomics of the strain and closely related species and subspecies highlighted their striking differences in gene properties and biological functions. Overall, the new strain exhibited low virulence and pathogenic potentials and thus, is regarded as a commensal member of the human microflora. The genetic divergence of K0074 from closely related strains offers a compelling foundation for future investigations into the strain's potential functional specialization and its adaptation within the vaginal microbiome.https://www.frontiersin.org/articles/10.3389/fmicb.2025.1625724/fullStreptococcusmicrobiomevaginal microbiomegenomicsphylogenomics
spellingShingle Jake Adolf V. Montecillo
Jake Adolf V. Montecillo
Jake Adolf V. Montecillo
Jung Hwa Lee
Jung Hwa Lee
Heon Jong Yoo
Yoo-Young Lee
Chul Min Park
Angela Cho
Hyunsu Lee
Jong Mi Kim
Jong Mi Kim
Nan Young Lee
Sun-Hyun Park
Nora Jee-Young Park
Nora Jee-Young Park
Hyung Soo Han
Hyung Soo Han
Hyung Soo Han
Gun Oh Chong
Gun Oh Chong
Incheol Seo
Incheol Seo
Incheol Seo
Characterization of Streptococcus mitis subsp. carlssonii isolated from human vagina: prevalence, phenotypic, and genomic insights
Frontiers in Microbiology
Streptococcus
microbiome
vaginal microbiome
genomics
phylogenomics
title Characterization of Streptococcus mitis subsp. carlssonii isolated from human vagina: prevalence, phenotypic, and genomic insights
title_full Characterization of Streptococcus mitis subsp. carlssonii isolated from human vagina: prevalence, phenotypic, and genomic insights
title_fullStr Characterization of Streptococcus mitis subsp. carlssonii isolated from human vagina: prevalence, phenotypic, and genomic insights
title_full_unstemmed Characterization of Streptococcus mitis subsp. carlssonii isolated from human vagina: prevalence, phenotypic, and genomic insights
title_short Characterization of Streptococcus mitis subsp. carlssonii isolated from human vagina: prevalence, phenotypic, and genomic insights
title_sort characterization of streptococcus mitis subsp carlssonii isolated from human vagina prevalence phenotypic and genomic insights
topic Streptococcus
microbiome
vaginal microbiome
genomics
phylogenomics
url https://www.frontiersin.org/articles/10.3389/fmicb.2025.1625724/full
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