Further dissection of Gardnerella vaginalis: description of Gardnerella lacydonensis sp. nov. (formerly genomic species 2), Gardnerella bretellae sp. nov. (formerly genomic species 9), Gardnerella massiliensis sp. nov. (formerly genomic species 14) and Gardnerella phocaeensis sp. nov.

Four bacterial strains – Marseille-Q9181 T , Marseille-QA0894 T , Marseille-Q9179 T and Marseille-Q2328 T – were isolated, the first three from vaginal samples and the last from a blood sample. MALDI-TOF MS analysis failed to assign these isolates to any known species within the genus Gardnerella . Consequently, phenotypic and taxonogenomic characterizations were conducted. All four strains were Gram-negative, non-motile and non-spore-forming coccobacilli. Strains Marseille-Q9181 T , Marseille-Q2328 T and Marseille-Q9179 T were facultative anaerobes with microaerophilic capabilities, whereas Marseille-QA0894 T was strictly anaerobic and microaerophilic. The dominant fatty acids (>10%) identified in strains Marseille-Q9181 T , Marseille-QA0894 T and Marseille-Q2328 T were C 16 : 0 , C 18 : 1 ω9c and C 18 : 0 . In strain Marseille-Q9179 T , C 18 : 0 was also among the most abundant fatty acids, along with the aforementioned three. Digital DNA–DNA hybridization (dDDH) values for strains Marseille-Q9181 T , Marseille-QA0894 T and Marseille-Q2328 T against Gardnerella vaginalis 1400E (genomic species 2), G. vaginalis 6119V5 (genomic species 9) and G. vaginalis NR010 (genomic species 14) were 72.1%, 72.4% and 75.5%, respectively. The corresponding OrthoANI values were 96.99%, 97.16% and 97.66%, all above the species demarcation threshold. In contrast, strain Marseille-Q9179 T exhibited both dDDH and OrthoANI values below the accepted thresholds (70% and 95–96%, respectively), suggesting that it represents a novel genomic lineage. Based on comprehensive phenotypic and genomic analyses, we propose that these strains represent four new species within the genus Gardnerella , for which the following names are proposed: Gardnerella lacydonensis sp. nov. (type strain: Marseille-Q9181 T =CSUR Q9181 T =CECT 31121 T ), Gardnerella bretellae sp. nov. (type strain: Marseille-QA0894 T =CSUR QA0894 T =CECT 31122 T ), Gardnerella massiliensis sp. nov. (type strain: Marseille-Q2328 T =CSUR Q2328 T =CECT 30239 T ) and Gardnerella phocaeensis sp. nov. (type strain: Marseille-Q9179 T =CSUR Q9179 T =CECT 31120 T ).