{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T06:08:19Z","timestamp":1788761299517,"version":"build-2803163510"},"reference-count":53,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T00:00:00Z","timestamp":1788739200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>\n                      The\n                      <jats:italic>Corynebacterium kroppenstedtii<\/jats:italic>\n                      complex (CKC) is increasingly recovered from mastitis, but its species boundaries and genomic diversity remain poorly resolved.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Following quality screening, we analysed 56 publicly available genomes of\n                      <jats:italic>C. kroppenstedtii<\/jats:italic>\n                      (Ck),\n                      <jats:italic>C. parakroppenstedtii<\/jats:italic>\n                      (Cpak), and\n                      <jats:italic>C. pseudokroppenstedtii<\/jats:italic>\n                      (Cpse). Taxonomic assignments were supported by average nucleotide identity (ANI), digital DNA\u2013DNA hybridization (dDDH), average amino acid identity (AAI)-derived protein similarity, and a core-genome-based phylogeny. We then examined pangenome structure, mobile elements, resistance genes, functional enrichment, and conserved gene neighbourhoods.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      ANI and core-gene phylogeny resolved Ck, Cpak, and Cpse as three species. The 4,706-cluster pangenome was open (fitted exponent\u202f=\u202f0.232) and comprised 1,751 core and 2,955 accessory clusters. Accessory-gene profiles further resolved three Cpak lineages, Cpak-P1 to Cpak-P3, concordant with the core-genome phylogeny. Insertion-sequence counts correlated with accessory cluster counts (Spearman\u2019s\n                      <jats:italic>\u03c1<\/jats:italic>\n                      \u202f=\u202f0.640,\n                      <jats:italic>p<\/jats:italic>\n                      \u202f=\u202f1.12\u202f\u00d7\u202f10\n                      <jats:sup>\u22127<\/jats:sup>\n                      ), and accessory clusters more frequently overlapped predicted mobile genetic elements (MGEs) than core clusters (402\/2,955 versus 98\/1,751; odds ratio\u202f=\u202f2.66,\n                      <jats:italic>p<\/jats:italic>\n                      \u202f=\u202f3.31\u202f\u00d7\u202f10\n                      <jats:sup>\u221219<\/jats:sup>\n                      ), supporting an MGE\u2013accessory association without implying causality. Seven ARG types were detected, most commonly\n                      <jats:italic>ermX<\/jats:italic>\n                      ,\n                      <jats:italic>cmx<\/jats:italic>\n                      ,\n                      <jats:italic>APH(6)-Id<\/jats:italic>\n                      , and\n                      <jats:italic>tet(W)<\/jats:italic>\n                      . AC410-like sequences occurred in 35\/56 genomes and were strongly associated with antimicrobial-resistance gene (ARG) carriage (34\/35 versus 4\/21; odds ratio\u202f=\u202f120.5,\n                      <jats:italic>p<\/jats:italic>\n                      \u202f=\u202f9.93 \u00d7 10\n                      <jats:sup>\u221210<\/jats:sup>\n                      ). In five of eight complete genomes, AC410-like sequences were located on the chromosome rather than on independent plasmid contigs. Functional enrichment and conserved gene neighbourhoods identified a candidate lipid\u2013iron locus shared by Cpak-P1 and Cpak-P2.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>These findings provide a lineage-resolved genomic framework for the CKC, demonstrating an open pangenome with substantial species- and lineage-associated accessory diversity. The results further identify AC410-like resistance-associated genomic backgrounds and a candidate lipid\u2013iron locus for future functional investigation.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fmicb.2026.1947083","type":"journal-article","created":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T05:33:59Z","timestamp":1788759239000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Comparative pangenomics of the Corynebacterium kroppenstedtii complex reveals species structure and accessory genome diversity"],"prefix":"10.3389","volume":"17","author":[{"given":"Xihua","family":"Zhou","sequence":"first","affiliation":[{"name":"Jiyang College, Zhejiang A&F University","place":["Zhuji, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yang","family":"Zhang","sequence":"additional","affiliation":[{"name":"Jiyang College, Zhejiang A&F University","place":["Zhuji, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yifan","family":"Qiu","sequence":"additional","affiliation":[{"name":"Jiyang College, Zhejiang A&F University","place":["Zhuji, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"Feng","sequence":"additional","affiliation":[{"name":"Jiyang College, Zhejiang A&F University","place":["Zhuji, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,7]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"D690","DOI":"10.1093\/nar\/gkac920","article-title":"CARD 2023: expanded curation, support for machine learning, and resistome prediction at the comprehensive antibiotic resistance database","volume":"51","author":"Alcock","year":"2023","journal-title":"Nucleic Acids Res."},{"key":"ref2","doi-asserted-by":"publisher","first-page":"32","DOI":"10.1046\/j.1442-9993.2001.01070.x","article-title":"A new method for non-parametric multivariate analysis of variance","volume":"26","author":"Anderson","year":"2001","journal-title":"Austral Ecol."},{"key":"ref3","doi-asserted-by":"publisher","first-page":"117","DOI":"10.4056\/sigs.531120","article-title":"Digital DNA-DNA hybridization for microbial species delineation by means of genome-to-genome sequence comparison","volume":"2","author":"Auch","year":"2010","journal-title":"Stand in Genomic Sci"},{"key":"ref4","doi-asserted-by":"publisher","first-page":"23479","DOI":"10.1038\/s41598-026-56520-7","article-title":"In silico genomic analysis of resistome, virulome, and mobilome of \u03b2-lactamase-producing Klebsiella pneumoniae","volume":"16","author":"Biswas","year":"2026","journal-title":"Sci. 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