Streptomyces sanguinis sp. nov., a Ceftriaxone-Resistant Strain Obtained From Human Blood and Reclassification of Streptomyces thermospinosisporus as Streptomyces thermocarboxydovorans subsp. thermospinosisporus subsp. nov.

Authors

Imen Nouioui, Jacqueline Wolf, Meina Neumann-Schaal, Christopher A Gulvik, John R McQuiston, Brent A Lasker

Published in

International journal of microbiology. Volume 2026. Pages 5214822. Epub Oct 02, 2026.

Abstract

The taxonomic position of an actinomycete, strain 15-116A^T, isolated from a blood culture of a 31-year-old male from the United States was determined using polyphasic taxonomic analysis. Genome-based phylogeny showed that the strain was closely related to Streptomyces composti, Streptomyces thermocarboxydovorans, and Streptomyces thermospinosisporus species. Digital DNA-DNA (dDDH) relatedness and average nucleotide identity (ANI) between the draft genome sequence of the strain and those of its closest phylogenomic neighbors listed above were between 35.9% and 37.3% (< 70%) and 88.5%, 88.1%, and 88.6% (95%-96.7%), respectively. However, the dDDH and ANI values between the genome sequence of S. thermocarboxydovorans JCM 10367^T and S. thermospinosisporus JCM 11756^T were 72.3% and 96.7%, respectively. These values are above the defined thresholds for prokaryotic species demarcation (70% dDDH and 95%-96.7% ANI) and fall within the dDDH range of 70%-79% for subspecies designation. Based on these findings and in accordance with the priority rule in nomenclature, S. thermospinosisporus is considered a later heterotypic synonym of S. thermocarboxydovorans and is classified as a subspecies of S. thermocarboxydovorans, for which the name S. thermocarboxydovorans subsp. thermospinosisporus subsp. nov. is proposed. Consequently, S. thermocarboxydovorans subsp. thermocarboxydovorans is created. Strain 15-116A^T was characterized by the presence of LL-diaminopimelic acid in its peptidoglycan; diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylinositol as the major phospholipids; MK-9(H₈) and MK-9(H₆) as the predominant menaquinones (> 10%); and iso-C_15:0, anteiso-C_15:0, iso-C_16:0, and anteiso-C_17:0 as the major fatty acids (> 10%). Morphological, phenotypic, and genomic traits distinguished strain 15-116A^T from its closest phylogenetic neighbors and highlighted the assignment of strain 15-116A^T (= DSM 106436^T = ATCC BAA-2935^T) to a novel species of the genus Streptomyces, for which the name Streptomyces sanguinis sp. nov. is proposed. Genome screening for virulence factor-associated genes showed that the strain harbored a gene encoding isocitrate lyase, which is required for persistent infection of Mycobacterium tuberculosis (YP_177728), as well as gene clusters associated with phenazine biosynthesis (NP_252902), unlike its close relatives. Moreover, strain 15-116A^T possessed a gene encoding elongation factor Tu (WP_003028672), which plays an important role in the bacterium's ability to adhere to host cells. However, further experimental studies are required to evaluate the pathogenic potential of this strain.

PMID:
42829520
Bibliographic data and abstract were imported from PubMed on 04 Oct 2026.

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